# BKG Ntrip Client (BNC)

### A toolkit for retrieving, decoding, converting and processing
real-time GNSS data streams

### Version 2.13

#### Authors

Georg Weber(1), Leoš Mervart(2), Andrea Stürze(1), Dirk Stöcker(3)
(1) Federal Agency for Cartography and Geodesy (BKG), Frankfurt, Germany
(2) Czech Technical University (CTU), Department of Geomatics, Prague, Czech Republic
(3) Alberding GmbH, Wildau, Germany

#### Contact

Feel free to send comments, suggestions or bug reports to:

     Federal Agency for Cartography and Geodesy (BKG)
     Department of Geodesy, Section Satellite Navigation
     Richard-Strauss-Allee 11
     60598 Frankfurt am Main, Germany
     email: igs-ip@bkg.bund.de

#### Legal Notice

BNC has been written under GNU General Public License (GPL). Source code is available from Subversion software archive http://software.rtcm-ntrip.org/svn/trunk/BNC. Precompiled binaries of BNC are available for MS Windows, Linux, and Mac OS X systems. They can be downloaded from http://igs.bkg.bund.de/ntrip/download.
Copyright © 2005-2022 Federal Agency for Cartography and Geodesy (BKG), Frankfurt, Germany

#### Citation

To help justify funding the development of BNC, we kindly ask users to include a citation when applying the software results in a publication. We suggest:

      Weber, G., L. Mervart, A. Stürze, A. Rülke and D. Stöcker (2016):
        BKG Ntrip Client, Version 2.12. Mitteilungen des Bundesamtes
        für Kartographie und Geodäsie, Vol. 49, Frankfurt am Main, 2016.

#### Table of Contents

1. General Information
1.1 Purpose
1.2 Supported GNSS
1.3 Data Flow
1.4 Handling
1.5 Installation
1.5.1 Compilation
1.6 Configuration
1.6.1 Examples
1.7 Limitations
1.8 Looking Back
2. Settings Details
2.1 Top Menu Bar
2.1.1 File
2.1.2 Help
2.2 Network
2.2.1 Proxy
2.2.2 SSL
2.3 General
2.3.1 Logfile
2.3.2 Append Files
2.3.3 Reread Configuration
2.3.4 Auto Start
2.3.5 Raw Output File
2.4 RINEX Observations
2.4.1 Filenames
2.4.2 Directory
2.4.3 File Interval
2.4.4 Sampling
2.4.5 Skeleton Extension
2.4.6 Skeleton Mandatory
2.4.7 Skeleton Directory
2.4.8 Script
2.4.9 Version 3 and 4
2.4.10 Version 2
2.5 RINEX Ephemeris
2.5.1 Directory
2.5.2 Interval
2.5.3 Port
2.5.4 Version
2.6 RINEX Editing & QC
2.6.1 Action
2.6.2 Input Files
2.6.3 Output Files
2.6.4 Logfiles
2.6.5 Plots for Signals
2.6.6 Directory for Plots
2.6.7 Set Edit Options
2.6.8 Command Line, No Window
2.7 SP3 Comparison
2.7.1 Input SP3 Files
2.7.2 Exclude Satellites
2.7.3 Logfile
2.8 Broadcast Corrections
2.8.1 Directory, ASCII
2.8.2 Interval
2.8.3 Port
2.8.4 Wait for Full Corr Epoch
2.9 Feed Engine
2.9.1 Port
2.9.2 Wait for Full Obs Epoch
2.9.3 Sampling
2.9.4 File
2.9.5 Port (unsynchronized)
2.10 Serial Output
2.10.1 Mountpoint
2.10.2 Port Name
2.10.3 Baud Rate
2.10.4 Flow Control
2.10.5 Parity
2.10.6 Data Bits
2.10.7 Stop Bits
2.10.8 NMEA
2.10.9 File
2.10.10 Height
2.10.11 Sampling
2.11 Outages
2.11.1. Observation Rate
2.11.2. Failure Threshold
2.11.3. Recovery Threshold
2.11.4. Script
2.12 Miscellaneous
2.12.1. Mountpoint
2.12.2. Log Latency
2.12.3. Scan RTCM
2.12.4. Port
2.13 PPP Client
2.13.1 PPP (1): Input and Output
2.13.1.1 Data Source
2.13.1.2 Corrections Stream
2.13.1.3 Corrections File
2.13.1.4 Ionosphere Stream
2.13.1.5 Ionosphere File
2.13.1.6 RINEX Observation File
2.13.1.7 RINEX Navigation File
2.13.1.8 ANTEX File
2.13.1.9 Coordinates File
2.13.1.10 BLQ File
2.13.1.11 Logfile Directory
2.13.1.12 NMEA Directory
2.13.1.13 SNX TRO Directory
2.13.1.13.1 Interval
2.13.1.13.2 Sampling
2.13.1.13.3 Analysis Center
2.13.1.13.4 Solution ID
2.13.2 PPP (2): Processing Options
2.13.2.1 GNSS Observations
2.13.2.2 Code Observations
2.13.2.3 Phase Observations
2.13.2.4 Elevation Dependent Weighting
2.13.2.5 Minimum Number of Observations
2.13.2.6 Minimum Elevation
2.13.2.7 Wait for Clock Corrections
2.13.2.8 Seeding
2.13.2.9 Pseudo Observations
2.13.2.10 GIM Pseudo Observations
2.13.3 PPP (3): Processed Stations
2.13.3.1 Station
2.13.3.2 Sigma North/East/Up
2.13.3.3 Noise North/East/Up
2.13.3.4 Tropo Sigma
2.13.3.5 Tropo Noise
2.13.3.6 NMEA Port
2.13.3.6 Signal Priorities
2.13.4 PPP (4): Plots
2.13.4.1 PPP Plot
2.13.4.2 Audio Response
2.13.4.3 Track Map
2.13.4.4 Dot-properties
2.13.4.4.1 Size
2.13.4.4.2 Color
2.13.4.5 Post Processing Speed
2.14 Combine Corrections
2.14.1 Combine Corrections Table
2.14.1.1 Add Row, Delete
2.14.1.2 Method
2.14.1.3 Maximal Residuum
2.14.1.4 Sampling
2.15 Upload Corrections
2.15.1 Add, Delete Row
2.15.2 Host, Port, Mountpoint, Ntrip Version, User and Password
2.15.3 System
2.15.4 Format
2.15.5 Center of Mass
2.15.6 SP3 File
2.15.7 RNX File
2.15.8 BSX File
2.15.9 PID, SID, IOD
2.15.10 Interval
2.15.11 Sampling
2.15.11.1 Orbits
2.15.11.2 SP3
2.15.11.3 RINEX
2.15.11.4 SINEX
2.15.12 Custom Trafo
2.15.13 ANTEX File
2.16 Upload Ephemeris
2.16.1 Host & Port
2.16.2 Mountpoint, Ntrip Version, User, Password
2.16.3 Satellite System
2.16.4 Sampling
2.17 Streams Canvas
2.17.1 Edit Streams
2.17.2 Delete Stream
2.17.3 Reconfigure Stream Selection On-the-fly
2.18 Logging Canvas
2.18.1 Log
2.18.2 Throughput
2.18.3 Latency
2.18.4 PPP Plot
2.19 Bottom Menu Bar
2.19.1 Add Stream
2.19.1.1 Add Stream - Coming from Caster
2.19.1.1.1 Caster Host and Port
2.19.1.1.2 Casters Table
2.19.1.1.3 User and Password
2.19.1.1.4 Get Table
2.19.1.1.5 Ntrip Version
2.19.1.1.6 Map
2.19.1.2 Add Stream - Coming from TCP/IP Port
2.19.1.3 Add Stream - Coming from UDP Port
2.19.1.4 Add Stream - Coming from Serial Port
2.19.2 Delete Stream
2.19.3 Map
2.19.4 Start
2.19.5 Stop
2.19.6 Help? = Shift+F1
2.20 Command Line Options
2.20.1 Version
2.20.2 Display
2.20.3 No Window Mode
2.20.4 File Mode
2.20.5 Configuration File
2.20.6 Configuration Options
3. Annex
3.1 RTCM Standards
3.1.1 Ntrip Version 1
3.1.2 Ntrip Version 2
3.1.3 RTCM Version 2
3.1.4 RTCM Version 3
3.2 Command Line Help
3.3 Further Reading
3.4 Abbreviations

List of Figures

Fig. | Title | Chapter
1 | Flowchart, BNC connected to a GNSS rover for Precise Point Positioning | 1.3
2 | Flowchart, BNC converting RTCM streams to RINEX batches | 1.3
3 | Flowchart, BNC feeding a real-time GNSS engine and uploading encoded Broadcast Corrections | 1.3
4 | Flowchart, BNC combining Broadcast Correction streams | 1.3
5 | Sections on BNC's main window | 1.4
6 | Management of configuration options in BNC | 1.6
7 | BNC's 'Network' panel configured to ignore eventually occurring SSL error messages | 2.2.2
8 | BNC translating incoming RTCM Version 3 Observation streams to 15 min RINEX Version 4 Observation files | 2.4
9 | Example for creating RINEX quality check analysis graphics output with BNC | 2.6.5
10 | Example for satellite availability, elevation and PDOP plots as a result of a RINEX quality check analysis with BNC | 2.6.5
11 | Sky plot examples for multipath, part of RINEX quality check analysis with BNC | 2.6.5
12 | Sky plot examples for signal-to-noise ratio, part of RINEX quality check analysis with BNC | 2.6.5
13 | Example for BNC's 'RINEX Editing Options' window | 2.6.7
14 | Example for RINEX file concatenation with BNC | 2.6.7
15 | Example for comparing two SP3 files with satellite orbit and clock data using BNC | 2.7
16 | Graphical results from an example comparison of two SP3 files with satellite orbit and clock data using BNC | 2.7.3
17 | Example for pulling, saving and output of Broadcast Corrections using BNC | 2.8.3
18 | Synchronized BNC output via IP port to feed a GNSS real-time engine | 2.9
19 | Flowcharts, BNC forwarding a stream to a serially connected receiver; sending NMEA sentences is mandatory for VRS streams | 2.10
20 | BNC pulling a RTCM Version 3 stream to feed a serial connected receiver with observations from a nearby reference station for conventional RTK | 2.10
21 | RTCM message numbers, latencies and observation types logged by BNC | 2.12
22 | Real-time Precise Point Positioning with BNC, PPP Panel 1 | 2.13.1
23 | Precise Point Positioning with BNC, PPP Panel 2 | 2.13.2
24 | Precise Point Positioning with BNC in 'Quick-Start' mode, PPP Panel 4 | 2.13.2.10
25 | Precise Point Positioning with BNC, PPP Panel 3 | 2.13.3
26 | Track of positions from BNC with OpenStreetMap in background | 2.13.4.3
27 | BNC combining Broadcast Correction streams | 2.14
28 | 'INTERNAL' PPP with BNC using a combination of Broadcast Corrections | 2.14
29 | BNC producing Broadcast Corrections from incoming precise orbits and clocks and uploading them to an Ntrip Broadcaster | 2.15
30 | Setting BNC's Custom Transformation Parameters window | 2.15.3
31 | BNC uploading a combined Broadcast Correction stream | 2.15.12
32 | BNC producing Broadcast Ephemeris streams from globally distributed RTCM streams; upload in RTCM format to an Ntrip Broadcaster | 2.16.3
33 | Bandwidth consumption of RTCM streams received by BNC | 2.18.2
34 | Latency of RTCM streams received by BNC | 2.18.3
35 | Example for time series plot of displacements produced by BNC | 2.18.4
36 | Steam input communication links accepted by BNC | 2.19
37 | BNC's 'Select Broadcaster' table | 2.19.1.1.2
38 | Broadcaster source-table shown by BNC | 2.19.1.1.4
39 | Stream distribution map shown by BNC as derived from Ntrip Broadcaster source-table | 2.19.1.1.6
40 | BNC configuration for pulling a stream via serial port | 2.19.1.4

List of Tables

Tab. | Title | Chapter
1 | Status of RTCM Version 3 message implementations in BNC supporting various GNSS systems | 1.2
2 | Contents and format of synchronized output of observations feeding a GNSS engine | 2.9

### 1. General Information

The BKG Ntrip Client (BNC) is a program for simultaneously retrieving, decoding, converting and processing or analyzing real-time GNSS data streams applying the 'Networked Transport of RTCM via Internet Protocol' (Ntrip) standard. It has been developed within the framework of the IAG sub-commission for Europe (EUREF) and the International GNSS Service (IGS). Although meant to be a real-time tool, it comes with some post processing functionality. It can be used for data coming from Ntrip Broadcasters like

- http://euref-ip.net/home
- http://igs-ip.net/home
- http://products.igs-ip.net/home

or similar caster installation.

Documentation
BNC provides context-sensitive help (What's This) related to specific objects. Furthermore, it comes with severl example configurations. The here presented documentation is available as part of the software, as a PDF file and can be find as well as an online documentation: http://software.rtcm-ntrip.org/export/HEAD/ntrip/trunk/BNC/src/bnchelp.html.

Note that some figures presented in this documentation may show screenshots from earlier versions of BNC. If so, there is either no relevant change compared to the current appearance of the program or no change at all.

Acknowledgements

- Oliver Montenbruck, German Space Operations Center, DLR, Oberpfaffenhofen, Germany published a RTCM Version 2 decoder unter GNU GPL which has been integrated in BNC.
- Andre Hauschild, German Space Operations Center, DLR, revised the RTCM Version 2 decoder and has provided a lot of hints regarding bugs and new features.
- Zdenek Lukes, Czech Technical University Prague, Department of Geodesy, extended the RTCM Version 2 decoder to handle message types 3, 20, 21, and 22 and added the loss of lock indicator.
- Lennard Huisman, Kadaster Netherlands, and Rolf Dach, Astronomical Institute University of Bern, assisted in handling satellite clocks in transformations from ITRF to regional reference frames.
- Denis Laurichesse, Centre National d'Etudes Spatiales (CNES), suggested synchronizing observations and clock corrections to reduce high frequency noise in PPP solutions.
- Alexis Blot, Centre National d'Etudes Spatiales (CNES), has provided a lot of hints regarding bugs and new features. Furthermore he has helped in the interoperability tests of RTCM-SSR and IGS-SSR format as well as the therefore used RTNET Interface.
- Loukis Agrotis, Symban Ltd, has provided a lot of hints regarding bugs and new features.
- Erwin Wiesensarter, Federal Agency for Cartography and Geodesy (BKG), provides actual builds of BNC for several Linux operating systems as well as for Mac OS X systems. Furthermore, he has provided some helpful scripts available under http://software.rtcm-ntrip.org/export/HEAD/ntrip/trunk/BNC/scripts.
- Peter Neumaier, Federal Agency for Cartography and Geodesy (BKG), provide the Windows MSI File and helps a lot regarding testing and user support.

#### 1.1 Purpose

Promoting Open RTCM Standards for streaming GNSS data over the Internet has been a major aspect in developing BNC as Open Source real-time software. Basically, the tool enables the test, validation and further evolution of new RTCM messages for precise satellite navigation. With high-level source code at hand, it also allows university education to catch up with comprehensive state-of-the-art positioning and potentially contributes fresh ideas which are free from any licensing.

BNC was designed to serve the following purposes:

- Retrieve real-time GNSS data streams available through the Ntrip transport protocol
- Retrieve real-time GNSS data streams via TCP directly from an IP address without using the Ntrip transport protocol
- Retrieve real-time GNSS data streams from a local UDP or serial port without using the Ntrip transport protocol
- Plot stream distribution map from Ntrip Broadcaster source-tables
- Generate RINEX Observation and Navigation files to support near real-time GNSS post processing applications
- Edit or concatenate RINEX files or carry out RINEX Quality Checks (QC)
- Handle RINEX Versions 2, 3 and 4 Observation and Navigation files
- Compare SP3 files containing satellite orbit and clock data
- Generate State Space Represenation (SSR) messages through an IP port to

- support real-time Precise Point Positioning on GNSS rovers
- support the (outside) combination of such streams as coming simultaneously from various correction providers

- Generate ephemeris and synchronized or unsynchronized observations epoch by epoch through an IP port to support real-time GNSS network engines
- Feed a stream into a GNSS receiver via serial communication link
- Monitor the performance of a network of real-time GNSS data streams to generate advisory notes in case of outages or corrupted streams
- Scan RTCM streams for incoming antenna information, observation types, message types and repetition rates and latencies and GLONASS slot numbers and frequency channels
- Carry out real-time Precise Point Positioning to determine GNSS rover positions
- Enable multi-station Precise Point Positioning for simultaneous processing of observations from a whole network of receivers
- Plot positions derived via PPP from RTCM streams or RINEX files on maps from OpenStreetMap
- Simultaneously process several SSR streams to produce, encode and upload combined SSR streams
- Estimate real-time tropospheric zenith path delays and save them in SINEX troposphere file format
- Read GNSS orbits and clocks in a plain ASCII format from an IP port. They can be produced by a real-time GNSS engine and should be referenced to the IGS Earth-Centered-Earth-Fixed (ECEF) reference system. BNC will then

- Convert the IGS Earth-Centered-Earth-Fixed orbits and clocks into Broadcast Corrections with radial, along-track and out-of-plane components
- Upload Broadcast Corrections as an RTCM-SSR or IGS-SSR stream to an Ntrip Broadcaster
- Refer the orbit and clock corrections to a specific reference system
- Log the Broadcast Clock Corrections as Clock RINEX files for further processing using other tools than BNC
- Log the Broadcast Orbit and Clock Corrections as SP3 files for further processing using other tools than BNC
- Log the Code and Phase Biases as SINEX Bias files for further processing using other tools than BNC

- Upload a Broadcast Ephemeris stream in RTCM Version 3 format;

BNC supports the following GNSS stream formats and message types:

- RTCM Version 2 message types
- RTCM Version 3 legacy message types
- RTCM Version 3 Multiple Signal Messages (MSM) and High Precision Multiple Signal Messages (HP MSM)
- RTCM Version 3 message types for Broadcast Ephemeris
- RTCM Version 3 State Space Representation (SSR) messages
- IGS State Space Representation (SSR) Version 1 messages
- RTNET, a plain ASCII format defined within BNC to receive SSR informations from a serving GNSS engine

BNC supports the following GNSS file formats:

- RINEX Version 2.11, 3.x and 4.x, Receiver Independent Exchange format for observation and navigation data
- The Extended Standard Product 3 Orbit Format SP3-d
- Clock RINEX Version 3.04 format for (station and) satellite clock solutions
- SINEX BIAS — Solution (Software/technique) INdependent EXchange Format for GNSS Biases Version 1.00
- SINEX TRO — Solution (Software/technique) INdependent EXchange Format for TROpospherican meteorological parameters Version 2.0
- ANTEX Version 1.4, Antenna Exchange format for Antenna Phase Center variations
- NMEA Version 0813, National Marine Electronics Association format for satellite navigation data
- A plain ASCII format defined within BNC to save all SSR informations within a file

Note that BNC allows to by-pass decoding and conversion algorithms for incoming streams, leaves whatever is received untouched to save it in files or output it through a local TCP/IP port.

#### 1.2 Supported GNSS

BNC is permanently completed to finally support all existing GNSS systems throughout all features of the program. The table below shows in detail which GNSS systems are supported so far by particular applications when using the latest BNC version. Application areas named here are:

- Decoding of RTCM, RTCM-SSR, IGS-SSR and RTNET streams
- RINEX and SINEX Bias file input and output
- SINEX TRO and SP3 file output
- Encoding of SSR and ephemeris messages
- Upload of SSR and ephemeris messages
- PPP (Precise Point Positioning)
- Combining/merging SSR or ephemeris messages from various real-time sources

The table indicates if a message implementation in BNC could so far only be based on a 'RTCM Proposal'.

Table 1: Status of RTCM Version 3 message implementations in BNC supporting various GNSS systems

Message Type # | Description | GNSS System | RTCM Proposal | Decoding | RINEX/ SP3 | Encoding | Upload | PPP | Combin.
General |  |  |  |  |  |  |  |  |
1005,1006 | Station |  |  | x |  |  |  |  |
1007,1008 | Antenna |  |  | x |  |  |  |  |
1033 | Receiver, Antenna |  |  | x |  |  |  |  |
1013 | System Parameters |  |  | x |  |  |  |  |
Navigation |  |  |  |  |  |  |  |  |
1019 | Ephemeris | GPS |  | x | x | x | x | x | x
1020 | Ephemeris | GLONASS |  | x | x | x | x | x | x
1045 | Ephemeris | Galileo F/Nav |  | x | x | x | x |  | x
1046 | Ephemeris | Galileo I/Nav |  | x | x | x | x | x | x
1043 | Ephemeris | SBAS | x | x | x | x | x |  | x
1044 | Ephemeris | QZSS |  | x | x | x | x |  | x
1042 | Ephemeris | BDS |  | x | x | x | x | x | x
1041 | Ephemeris | IRNSS |  | x | x | x | x |  | x
Observation |  |  |  |  |  |  |  |  |
1001-4 | Conventional Messages | GPS |  | x | x |  |  | x |
1009-12 | Conventional Messages | GLONASS |  | x | x |  |  | x |
Observation |  |  |  |  |  |  |  |  |
1071-77 | Multiple Signal Message | GPS |  | x | x |  |  | x |
1081-87 | Multiple Signal Message | GLONASS |  | x | x |  |  | x |
1091-97 | Multiple Signal Message | Galileo |  | x | x |  |  | x |
1101-07 | Multiple Signal Message | SBAS |  | x | x |  |  |  |
1111-17 | Multiple Signal Message | QZSS |  | x | x |  |  |  |
1121-27 | Multiple Signal Message | BDS |  | x | x |  |  | x |
1131-37 | Multiple Signal Message | IRNSS |  | x | x |  |  |  |
RTCM SSR I |  |  |  |  |  |  |  |  |
1057 | Orbit Corrections | GPS |  | x | x | x | x | x | x
1063 | Orbit Corrections | GLONASS |  | x | x | x | x | x | x
1240 | Orbit Corrections | Galileo | x | x | x | x | x | x | x
1246 | Orbit Corrections | SBAS | x | x | x | x | x |  | x
1252 | Orbit Corrections | QZSS | x | x | x | x | x |  | x
1258 | Orbit Corrections | BDS | x | x | x | x | x | x | x
1058 | Clock Corrections | GPS |  | x | x | x | x | x | x
1064 | Clock Corrections | GLONASS |  | x | x | x | x | x | x
1241 | Clock Corrections | Galileo | x | x | x | x | x | x | x
1247 | Clock Corrections | SBAS | x | x | x | x | x |  | x
1253 | Clock Corrections | QZSS | x | x | x | x | x |  | x
1259 | Clock Corrections | BDS | x | x | x | x | x | x | x
1059 | Code Biases | GPS |  | x | x | x | x | x | x
1065 | Code Biases | GLONASS |  | x | x | x | x | x | x
1242 | Code Biases | Galileo | x | x | x | x | x | x | x
1248 | Code Biases | SBAS | x | x | x | x | x |  | x
1254 | Code Biases | QZSS | x | x | x | x | x |  | x
1260 | Code Biases | BDS | x | x | x | x | x | x | x
1061, 1062 | User Range Accuracy, HR | GPS |  | x |  |  |  |  |
1067, 1068 | User Range Accuracy, HR | GLONASS |  | x |  |  |  |  |
1244, 1245 | User Range Accuracy, HR | Galileo | x | x |  |  |  |  |
1250, 1251 | User Range Accuracy, HR | SBAS | x | x |  |  |  |  |
1256, 1257 | User Range Accuracy, HR | QZSS | x | x |  |  |  |  |
1262, 1263 | User Range Accuracy, HR | BDS | x | x |  |  |  |  |
1060 | Comb. Orbits & Clocks | GPS |  | x | x | x | x | x | x
1066 | Comb. Orbits & Clocks | GLONASS |  | x | x | x | x | x | x
1243 | Comb. Orbits & Clocks | Galileo | x | x | x | x | x | x | x
1249 | Comb. Orbits & Clocks | SBAS | x | x | x | x | x |  | x
1255 | Comb. Orbits & Clocks | QZSS | x | x | x | x | x |  | x
1261 | Comb. Orbits & Clocks | BDS | x | x | x | x | x | x | x
RTCM SSR II |  |  |  |  |  |  |  |  |
1264 | VTEC | GNSS | x | x | x | x | x | x |
1265 | Phase Biases | GPS | x | x | x | x | x | x |
1266 | Phase Biases | GLONASS | x | x | x | x | x | x |
1267 | Phase Biases | Galileo | x | x | x | x | x | x |
1268 | Phase Biases | SBAS | x | x | x | x | x |  |
1269 | Phase Biases | QZSS | x | x | x | x | x |  |
1270 | Phase Biases | BDS | x | x | x | x | x | x |
IGS SSR |  |  |  |  |  |  |  |  |
4076 | IGS SSR | GNSS |  | x | x | x | x | x | x

#### 1.3 Data Flow

BNC can be used in different contexts with varying data flows. Typical real-time communication follows the Ntrip protocol over TCP/IP (also via SSL), RTSP/RTP or UDP, plain TCP/IP protocol, or serial communication links. Stream content could be observations, ephemeris, SSR products or NMEA sentences.

The first of the following figures shows a flow chart of BNC connected to a GNSS receiver providing observations via serial or TCP communication link for the purpose of Precise Point Positioning.

Figure 1: Flowchart, BNC connected to a GNSS rover for Precise Point Positioning

The second figure shows the conversion of RTCM streams to RINEX files.

Figure 2: Flowchart, BNC converting RTCM streams to RINEX batches

The third figure shows a flow chart of BNC feeding a real-time GNSS engine, which estimates precise orbits and clocks. BNC is used in this scenario to encode SSR corrections to RTCM-SSR or IGS-SSR and upload them to an Ntrip Broadcaster.

Figure 3: Flowchart, BNC feeding a real-time GNSS engine and uploading encoded Broadcast Corrections

The fourth figure shows BNC combining several Broadcast SSR Correction streams to disseminate the combination product while saving results in SP3, Clock RINEX and SINEX Bias files.

Figure 4: Flowchart, BNC combining Broadcast Correction streams

#### 1.4 Handling

Although BNC is mainly a real-time tool to be operated online, it can be run offline

- To simulate real-time observation situations for debugging purposes;
- For post processing purposes.

Furthermore, apart from its regular window mode, BNC can be run as a batch/background job in a 'no window' mode, using processing options from a previously saved configuration or from command line.

Unless it runs offline, BNC

- Requires access to the Internet with a minimum of about 2 to 6 kbits/sec per stream depending on the stream format and the number of visible satellites. You need to make sure that the connection can sustain the required bandwidth;
- Requires the clock of the host computer to be properly synchronized;
- Has the capacity to retrieve hundreds of GNSS data streams simultaneously. Please be aware that such usage may incur a heavy load on the Ntrip Broadcaster side depending on the number of streams requested. We recommend limiting the number of streams where possible to avoid unnecessary workload.

The main window of BNC shows a 'Top menu bar' section, a 'Settings' sections with panels to set processing options, a 'Streams' section, a section for 'Log' tabs, and a 'Bottom menu bar' section, see figure below.

Figure 5: Sections on BNC's main window

Running BNC in interactive mode requires graphics support. This is also required in batch mode when producing plots. Windows and Mac OS X systems always support graphics. However, when using BNC in batch mode on Linux systems for producing plots, you need to make sure that at least a virtual X-Server like 'Xvfb' is installed and the '-display' command line option is used. Alternatively, the command line option '--plattform' can be tried to use with the argument 'offscreen' and the '-display' command line option.

The usual handling of BNC is that you first select a number of streams ('Add Stream'). Any stream configured to BNC shows up on the 'Streams' canvas in the middle of BNC's main window. You then go through BNC's various configuration panels to set a combination of input, processing and output options before you start the program ('Start'). Most configuration panels are dedicated to a certain function of BNC. If the first option field on such a configuration panel is empty, the affected functionality is deactivated.

Records of BNC's activities are shown in the 'Log' tab which is part of the 'Log' canvas. The bandwidth consumption per stream, the latency of incoming observations, and a PPP time series for coordinate displacements are also part of that canvas and shown in the 'Throughput', 'Latency' and 'PPP Plot' tabs.

Configuration options are usually first set using BNC's Graphical User Interface (GUI), then saved in a configuration file. For routine operations in batch mode all of BNC's configuration options can be extracted from the configuration file and applied using the program's Command Line Interface (CLI).

#### 1.5 Installation

Precompiled builds of BNC are available for Windows, Linux, and Mac OS X systems. They can be downloaded for installation from https://igs.bkg.bund.de/ntrip/bnc. Please ensure that you always use the latest version of the program.

Windows: A dynamically compiled shared library build for Mircrosoft Windows systems is provided as Microsoft Installer (MSI) file. MSI files are used for installation, storage, and removal of programs. The BNC files are contained in a MSI package, which is used with the program's client-side installer service, an .EXE file, to open and install the program. We used the MSVC 2019 compiler to create BNC for Windows. After installation your 'bnc.exe' file shows up e.g. under 'All Programs'.

Linux: Shared library builds for BNC are provided for a selection of Linux distributions. Download the ZIP archive for a version which fits to your Linux system, unzip the archive and run the included BNC binary.

Mac OS X Build: A shared library 'Disk iMaGe' (DMG) file is provided for BNC on OS X systems; it also comes in a ZIP archive. The DMG file format is used in the Mac for distributing software. Mac install packages appear as a virtual disk drive. After download, when the DMG file icon is double clicked, the virtual drive is 'mounted' on the desktop. Install BNC by dragging the 'bnc.app' icon to your '/Applications' folder. To start BNC, double click on '/Applications/bnc.app'. You could also start BNC via Command Line Interface (CLI) using command '/Applications/bnc.app/Contents/MacOS/bnc'.

#### 1.5.1 Compilation

BNC has been written as Open Source and published under GNU General Public License (GPL). The latest source code can be checked out from the Subversion repository at http://software.rtcm-ntrip.org/svn/trunk/BNC. A ZIP archive available from https://igs.bkg.bund.de/ntrip/bnc provides the source code.

The following describes how you can produce your own builds of BNC on Windows, Linux, and Mac systems. It is likely that BNC can also be compiled on other systems where a GNU compiler and Qt Version 5 or any later version is installed.

Static versus Shared Libraries
You can produce static or shared library builds of BNC. Static builds are sufficient in case you do not want BNC to produce track maps on top of OpenStreetMap (OSM). The usage would require the QtWebEngineWidges library which can only be part of BNC builds from shared Qt libraries. Hence, having a shared library Qt installation available is a precondition for producing a shared library build of BNC.

MS Windows Systems, Shared Library
This section contains some hints how to build a shared Qt 15.5.8 library on MS Windows systems to then create your own shared build of BNC. But is is highly recommended to use the dynamically compiled shared library build for Mircrosoft Windows systems which is provided as Microsoft Installer (MSI) file.

- Support for Secure Sockets Layer (SSL) communication is provided by the OpenSSL Toolkit, which must be obtained separately. Download the latest version of the toolkit that is supported by Qt and install OpenSSL libraries in C:\OpenSSL-Win64. The OpenSSL libraries are looked up first in the drectory of the executable, then in the Windows System directory, and finally in all directories listed in the PATH environment variable. You can configure how Qt uses OpenSSL by setting either the -openssl / -openssl-runtime or -openssl-linked configure flags. To link Qt Network against OpenSSL libraries, set the -openssl-linked configure argument and use the OPENSSL_PREFIX variable to let Qt correctly locate and build against your OpenSSL installation. For example: configure -openssl-linked OPENSSL_PREFIX="C:\OpenSSL-Win64".
- The following tools are required at build time:
  - Python 2.7.5 or later. Python 3 is not supported.
  - Windows binaries of Bison, Flex, GPerf from the GnuWin32 project (http://gnuwin32.sourceforge.net/), required to build QtWebEngine
  - Node.js version 12 or later
  - Visual Studio 2019 or clang-cl (msvc mode) version 8 or later, required to build QtWebEngine
  - Jom is recommended because it is a clone of nmake to support the execution of multiple independent commands in parallel. It basically adds the -j command line switch similar to GNU make
  - Active Template Library (ATL), usually included in the Visual Studio installation
  - Windows 10 SDK version 10.0.19041 or later
  and its location should be listed in the PATH environment variable.
- To use OpenGL, pass the command line option '-opengl dynamic' to the configure script.
- Download the file 'qt-everywhere-opensource-src-5.15.8.zip' e.g. from https://download.qt.io/official_releases/qt/5.15/5.15.8/single/ and unzip the ZIP archive and move the contents of the contained directory into a directory e.g. C:\Qt\qt-everywhere-src-5.15.8.
- Open a x64 Native Tools Command Promt for VS 2019
- Go to directory C:\Qt\qt-everywhere-src-5.15.8 and configure Qt using command

      .\configure -prefix C:\Qt\5.15.8\ -opensource -release -platform win32-msvc -icu -I C:\icu-windows\include -L C:\icu-windows\lib64 -qt-pcre -qt-zlib -qt-freetype -qt-harfbuzz -qt-libpng -qt-libjpeg -qt-sqlite -qt-tiff -qt-webp -mp -confirm-license -openssl-linked OPENSSL_PREFIX="C:\OpenSSL-Win64" -opengl dynamic -webengine-proprietary-codecs -recheck-all -nomake tests -nomake examples -no-sql-mysql -skip qtdoc -skip qtquickcontrols -skip qtscript -skip qtxmlpatterns -skip qtandroidextras -skip qtgamepad -skip qtmultimedia -skip qtpurchasing -skip qtwayland -skip qtspeech -skip qtlottie -skip qtscxml -skip qt3d -skip qtcharts -skip qtdatavis3d -skip qtgraphicaleffects -skip qtquickcontrols -skip qtquickcontrols2 -skip qtremoteobjects

- Compile Qt using command

        jom or nmake

- Install Qt using command

        jom install or nmake install

- Create somewhere a file QtEnv.bat with the following content:

         set QTDIR=C:\Qt\5.15.8
         set PATH=%PATH%C:\Qt\5.15.8\bin;
         set QMAKESPEC=C:\Qt\5.15.8\mkspecs\win32-msvc

  and exceute file QtEnv.bat
- Download latest BNC from SVN repository http://software.rtcm-ntrip.org/svn/trunk/BNC.
- Go to directory BNC and enter command

         qmake bnc.pro

- Enter command

         nmake

- Find binary file bnc.exe in directory named src.

Linux Systems
Qt development tools have to be installed as well as some other libraries e.g. for openssl. They can be easily installed from your system repositories. BNC 2.13 needs Qt5. See the docker files for the most used Linux systems. To compile the BNC program, you first download the source code from the SVN repository http://software.rtcm-ntrip.org/svn/trunk/BNC. Go to directory BNC and run the following commands:

        qmake bnc.pro
        make

You will find a build of BNC in directory BNC.

Mac OS X Systems

Please use the precompiled build of BNC

#### 1.6 Configuration

As a default, configuration files for running BNC on Unix/Linux/Mac OS X systems are saved in directory '${HOME}/.config/BKG'. On Windows systems, they are typically saved in directory 'C:/Documents and Settings/Username/.config/BKG'. The default configuration filename is 'BNC.bnc'.

The default filename 'BNC.bnc' can be changed and the file content can easily be edited. On graphical user interfaces it is possible to Drag & Drop a configuration file icon to start BNC (not on Mac OS X systems). It is also possible to start and configure BNC via command line. Some configuration options can be changed on-the-fly. See annexed 'Command Line Help' for a complete set of configuration options.

BNC maintains configuration options at three different levels:

- GUI, input fields level
- Active configuration level
- Configuration file, disk level

Figure 6: Management of configuration options in BNC:

| Left: | BNC in graphics mode; active configuration options are introduced through GUI input fields and finally saved on disk
| Middle: | BNC in 'no window' mode; active configuration options are read from disk
| Right: | BNC in 'no window' mode without configuration file; default configuration options can be overwritten via command line options

Configuration options are usually specified using GUI input fields (1) after launching BNC. When hitting the 'Start' button, configuration options are transferred one level down to become BNC's active configuration (2), allowing the program to begin its operation. Pushing the 'Stop' button ends data processing so that the user can finally terminate BNC through 'File'->'Quit'->'Save Options' which saves processing options in a configuration file to disk (3). It is important to understand that:

- Active configuration options (2) are independent from GUI input fields and configuration file content.
- Hence changing configuration options at GUI level (1) while BNC is already processing data does not influence a running job.
- Editing configuration options at disk level (3) while BNC is already processing data does also not influence a running job. However, there are two exceptions which force BNC to update certain active options on-the-fly:

- Pushing the 'Reread & Save Configuration' button lets BNC immediately reread its configuration from GUI input fields to make them active configuration options. Then BNC saves them on disk.
- Specifying the 'Reread configuration' option lets BNC reread its configuration from disk at pre-defined intervals.

- A specific BNC configuration can be started in 'no window' mode from scratch without a configuration file if options for the active configuration level (2) are provided via command line.

#### 1.6.1 Examples

BNC comes with a number of configuration examples which can be used on all operating systems. Copy the complete directory 'Example_Configs' which comes with the software to your disc. It includes sub-directories 'Input' and 'Output'. There are several ways to start BNC using one of the example configurations:

- On graphical systems (except for Mac systems), you may use the computer mouse to 'drag' a configuration file icon and 'drop' it on top of BNC's program icon.
- You could also start BNC using a command line for naming a specific configuration file (suggested e.g. for Mac systems):
  /Applications/bnc.app/Contents/MacOS/bnc --conf <configFileName>
- On non-graphical systems or when running BNC in batch mode in the background you may start the program using a command line with a configuration file option in 'no window' mode (example for Windows systems):
  bnc.exe --conf <configFileName> --nw

Although it's not a must, we suggest that you always create BNC configuration files with filename extension '.bnc'.

We furthermore suggest for convenience reasons that you configure your system to automatically start BNC when you double-click a file with the filename extension '.bnc'. The following describes what to do on MS Windows systems to associate the BNC program to such configuration files:

1. Right-click a file that has the extension '.bnc' and then click 'Open'. If the 'Open' command is not available, click 'Open With' or double-click the file.
2. Windows displays a dialog box that says that the system cannot open this file. The dialog box offers several options for selecting a program.
3. Click 'Select the program from a list', and then click 'OK'.
4. The 'Open With' dialog box is displayed. Click 'Browse', locate and then click the BNC program, and then click 'Open'.
5. Click to select the 'Always use the selected program to open this kind of file' check box.
6. Click 'OK'.

Some of the presented example configurations contain a user ID 'Example' with a password 'Configs' for accessing a few GNSS streams from public Ntrip Broadcasters. This free generic account is arranged for convenience reasons only. Please be so kind as to replace the generic account details as well as the place holder's 'User' and 'Pass' by the personal user ID and password you receive following an online registration through http://register.rtcm-ntrip.org.

Note that the account for an Ntrip Broadcaster is usually limited to pulling a specified maximum number of streams at the same time. As running some of the example configurations requires pulling several streams, it is suggested to make sure that you do not exceed your account's limits.

Make also sure that sub-directories 'Input' and 'Output' which are part of the example configurations exist on your system or adjust the affected example configuration options according to your needs.

Some BNC options require Antenna Phase Center variations as made available from IGS through so-called ANTEX files at https://files.igs.org/pub/station/general/igs20.atx. An example ANTEX file 'igs20.atx' is part of the BNC package for convenience.

The example configurations assume that no proxy protects your BNC host. Should a proxy be operated in front of BNC then you need to introduce its name or IP and port number in the 'Network' panel.

(A) Working with Configuration Files
You should be able to run all configuration file examples without changing contained options. However, configuration 'Upload.bnc' is an exception because it requires an input stream from a connected network engine.

1. Configuration File 'RinexObs.bnc'
   Purpose: Convert RTCM streams to RINEX Observation files. The configuration pulls RTCM Version 3 streams from Ntrip Broadcasters using Ntrip Version 2 to generate 15min 1Hz RINEX Version 4 Observation files. See https://igs.bkg.bund.de/ntrip/#rtcm-obs for observation stream resources.
2. Configuration File 'RinexEph.bnc'
   Purpose: Convert a RTCM stream with navigation messages to RINEX Navigation files. The configuration pulls a RTCM Version 3 stream with Broadcast Ephemeris coming from the real-time EUREF and IGS networks and saves hourly RINEX Version 4 Navigation files. See https://igs.bkg.bund.de/ntrip/#rtcm-eph for further real-time Broadcast Ephemeris resources.
3. Configuration File 'BrdcCorr.bnc'
   Purpose: Save Broadcast Corrections from RTCM SSR messages in hourly plain ASCII files. See https://igs.bkg.bund.de/ntrip/#rtcm-corr for various real-time IGS or EUREF orbit/clock correction products.
4. Configuration File 'RinexConcat.bnc'
   Purpose: Concatenate several RINEX Version 3 files to produce one compiled file and edit the marker name in the file header. The sampling interval is set to 30 seconds. See section 'RINEX Editing & QC' in the documentation for examples on how to call BNC from command line in 'no window' mode for RINEX file editing, concatenation and quality check.
5. Configuration File 'RinexQC.bnc'
   Purpose: Check the quality of a RINEX Version 4 file by means of a multipath analysis. Results are saved on disk in terms of a plot in PNG format. See section 'RINEX Editing & QC' in the documentation for examples on how to call BNC from command line in 'no window' mode for RINEX file editing, concatenation and quality check.
6. Configuration File 'RTK.bnc'
   Purpose: Feed a serial connected receiver with observations from a nearby reference station for conventional RTK. The stream is scanned for RTCM messages. Message type numbers and latencies of incoming observations are reported in BNC's logfile.
7. Configuration File 'FeedEngine.bnc'
   Purpose: Feed a real-time GNSS engine with observations from remote reference stations. The configuration pulls a single stream from an Ntrip Broadcaster. You could also pull several streams from different casters. Incoming observations are decoded, synchronized, output through a local IP port and also saved into a file. Failure and recovery thresholds are specified to inform about outages.
8. Configuration File 'PPP.bnc'
   Purpose: Precise Point Positioning from observations of a rover receiver. The configuration reads RTCM Version 3 observations, a Broadcast Ephemeris stream and a stream with Broadcast Corrections. Positions are saved in the logfile. More detailed PPP results are saved in the PPP logfile.
9. Configuration File 'PPPNet.bnc'
   Purpose: Precise Point Positioning for several rovers or receivers from an entire network of reference stations in one BNC job. The possible maximum number of PPP solutions per job depends on the processing power of the hosting computer. This example configuration reads two RTCM Version 3 observation streams, a Broadcast Ephemeris stream and a stream with Broadcast Corrections. Detailed PPP Results for the two stations are saved in PPP logfiles.
10. Configuration File 'PPPQuickStart.bnc'
    Purpose: Precise Point Positioning in Quick-Start mode from observations of a static receiver with precisely known position. The configuration reads RTCM Version 3 observations, Broadcast Corrections and a Broadcast Ephemeris stream. Positions are saved in NMEA format on disc. They are also output through IP port for real-time visualization with tools like RTKPLOT. Positions are saved in the logfile.
11. Configuration File 'PPPPostProc.bnc'
    Purpose: Precise Point Positioning in post processing mode. BNC reads RINEX Version 3 Observation and Navigation files and a Broadcast Correction file. Optionally, an Ionosphere file containing VTEC informations can be used. If such a file is not specified, VTEC informations from the Broadcast Corrections file are used. PPP processing options are set to support the Quick-Start mode. The output is saved in a specific post processing logfile and contains coordinates derived over time following the implemented PPP filter algorithm.
12. Configuration File 'PPPOsm.bnc'
    Purpose: Track BNC's point positioning solutions using OpenStreetMap as background. BNC reads a RINEX Observation file and a RINEX Navigation file to carry out a 'Standard Point Positioning' solution in post processing mode. Although this is not a real-time application it requires the BNC host to be connected to the Internet. Specify a computation speed, then hit button 'Open Map' to open the track map, then hit 'Start' to visualize receiver positions on top of OSM maps.
13. Configuration File 'PPPGalHAS.bnc'
    Purpose: Precise Point Positioning in Quick-Start mode with SSR corrections from the Galileo HAS Internet Data Distribution (IDD) interface with observations of a static receiver with quite precisely known position. Because the Galileo HAS provides Code Biases and corrections for satellite orbits and clocks for GPS and Galileo, the configuration uses GPS and Galileo navigation data only. Access to the Galileo HAS Internet Data Distribution is available by registration: https://www.gsc-europa.eu/galileo/services/galileo-high-accuracy-service-has/internet-data-distribution-registration-form Purpose: Single Point Positioning in Quick-Start mode from observations of a static receiver with quite precisely known position. The configuration uses Galileo observations only and a Broadcast Ephemeris stream.
14. Configuration File 'SaveSp3.bnc'
    Purpose: Produces SP3 files from a Broadcast Ephemeris stream and a Broadcast Correction stream. The Broadcast Correction stream is formally introduced in BNC's 'Combine Corrections' table. Note that producing SP3 requires an ANTEX file because SP3 file content should be referred to CoM..
15. Configuration File 'Sp3ETRF2000PPP.bnc'
    Purpose: Produce SP3 files from a Broadcast Ephemeris stream and a stream carrying ETRF2000 Broadcast Corrections. The Broadcast Correction stream is formally introduced in BNC's 'Combine Corrections' table. The configuration leads to a SP3 file containing orbits also referred to ETRF2000. Pulling in addition observations from a reference station at precisely known ETRF2000 position allows comparing an 'INTERNAL' PPP solution with a known ETRF2000 reference coordinate.
16. Configuration File 'Upload.bnc'
    Purpose: Upload orbits and clocks from a real-time GNSS engine to an Ntrip Broadcaster. For that the configuration reads precise orbits and clocks in RTNET format. It also reads a stream carrying Broadcast Ephemeris. BNC converts the orbits and clocks into Broadcast Corrections and encodes them to IGS-SSR messages to finally upload them to an Ntrip Broadcaster. The Broadcast Correction stream is referred to satellite Antenna Phase Center (APC) and reference system IGS20. Orbits are saved on disk in SP3 format and clocks are saved in Clock RINEX format.
17. Configuration File 'Combi.bnc'
    Purpose: Pull 2 streams carrying Broadcast Corrections, and Satellite Code Biases together with Broadcast Ephemeris from an Ntrip Broadcaster to produce a combined Broadcast Correction stream. BNC encodes the combination product in IGS-SSR messages and uploads them to an Ntrip Broadcaster. The Broadcast Correction stream is referred to satellite Antenna Phase Center (APC) and not to satellite Center of Mass (CoM). Its reference system is IGS20. Orbits are saved in SP3 format (referred to CoM) and clocks in Clock RINEX format.
18. Configuration File 'CombiPPP.bnc'
    Purpose: This configuration equals the 'Combi.bnc' configuration. However, the combined Broadcast Corrections are in addition used for an 'INTERNAL' PPP solutions based on observations from a static reference station with known precise coordinates. This allows a continuous quality check of the combination product through observing coordinate displacements.
19. Configuration File 'UploadEph.bnc'
    Purpose: Pull a number of streams from reference stations to get the contained Broadcast Ephemeris messages. They are encoded to RTCM Version 3 format and uploaded for the purpose of providing a Broadcast Ephemeris stream with an update rate of 5 seconds.
20. Configuration File 'CompareSp3.bnc'
    Purpose: Compare two SP3 files to calculate RMS values for orbit and clock differences. GPS satellite G05 and GLONASS satellite R18 are excluded from this comparison. Comparison results are saved in a logfile.
21. Configuration File 'Empty.bnc'
    Purpose: Provide an empty example configuration file for BNC which only contains the default settings.

(B) Working with Command Line configuration options
The following configuration examples make use of BNC's 'Command Line Interface' (CLI). Configuration options are exclusively specified via command line. No configuration file is used. Examples are provided as shell scripts for a Linux system. They call BNC in 'no window' batch mode (command line option -nw). The scripts expect 'Example_Configs' to be the current working directory.

22. Shell Script 'RinexQC.sh'
    Purpose: Equals configuration file example 'RinexQC.bnc', checks the quality of a RINEX Version 4 file by means of a multipath analysis. The platform offscreen is used while producing plot files in PNG format. BNC is offline. All results are saved on disk.
23. Shell Script 'RinexConcat.sh'
    Purpose: Equals configuration file example 'RinexConcat.bnc', concatenates several RINEX Version 3 files to produce one compiled file and edit the marker name in the file header. The sampling interval is set to 30 seconds. BNC is offline.
24. Shell Script 'RinexEph.sh'
    Purpose: Equals configuration file example 'RinexEph.bnc', converts a RTCM stream with navigation messages to RINEX Navigation files. The configuration pulls a RTCM Version 3 stream with Broadcast Ephemeris coming from the real-time EUREF and IGS networks and saves hourly RINEX Version 4 Navigation files. BNC runs online until it's terminated after 10 seconds. See https://igs.bkg.bund.de/ntrip/#rtcm-eph for further real-time Broadcast Ephemeris resources.
25. Shell Script 'ScanLate.sh'
    Purpose: Scan an observation stream for contained RTCM message types, print observation latencies. The output is saved in a logfile. Latencies are reported every 10 seconds. BNC runs online until it's terminated after 20 seconds.
26. Shell Script 'RinexObs.sh'
    Purpose: Equals configuration file example 'RinexObs.bnc', converts RTCM streams to RINEX Observation files. The configuration pulls streams from two Ntrip Broadcasters using Ntrip Version 2 to generate 15min 1Hz RINEX Version 4 Observation files. See https://igs.bkg.bund.de/ntrip/#rtcm-obs for observation stream resources. BNC runs online until it's terminated after 30 seconds.

(C) Command Line configuration options overwriting Configuration File options
For specific applications you may like to use your own set of standard configuration options from a configuration file and update some of its content via command line. When using a configuration file together with command line configuration options in one BNC call, the command line configuration options will always overrule options contained in the configuration file.

27. Shell Script 'CompareSp3.sh'
    Purpose: Equals configuration file example 'CompareSp3.bnc', compares two SP3 files to calculate RMS values for orbit and clock differences. However, instead of excluding GPS satellite G05 and GLONASS satellite R18 from the comparison as specified in 'CompareSp3.bnc', GPS satellite G06 and all GLONASS satellites are excluded via command line option. BNC runs offline. Comparison results are saved in a logfile.

#### 1.7 Limitations

- In Qt-based desktop environments (like KDE) on Unix/Linux platforms it may happen that you experience a crash of BNC at startup even when running the program in the background using the '-nw' option. This is a known bug most likely resulting from an incompatibility of Qt libraries in the environment and in BNC. Entering the command 'unset SESSION_MANAGER' before running BNC may help as a work-around.
- Using RTCM Version 3 to produce RINEX files, BNC will properly handle most message types. However, when handling message types 1001, 1003, 1009 and 1011 where the ambiguity field is not set, the output will be no valid RINEX. All values will be stored modulo 299792.458 (speed of light).
- Using RTCM Version 2, BNC will only handle message types 18 and 19 or 20 and 21 together with position and the antenna offset information carried in types 3 and 22. Note that processing carrier phase corrections and pseudo-range corrections contained in message types 20 and 21 needs access to Broadcast Ephemeris. Hence, whenever dealing with message types 20 and 21, make sure that Broadcast Ephemeris become available for BNC through also retrieving at least one RTCM Version 3 stream carrying message types 1019 (GPS ephemeris) and 1020 (GLONASS ephemeris).
- BNC's 'Get Table' function only shows the STR records of a source-table. You can use an Internet browser to download the full source-table content of any Ntrip Broadcaster by simply entering its URL in the form of http://host:port. Data field number 8 in the NET records may provide information about where to register for an Ntrip Broadcaster account.
- EUREF as well as IGS adhere to an open data policy. Streams are made available through Ntrip Broadcasters at http://euref-ip.net/home, http://igs-ip.net/home and http://products.igs-ip.net/home free of charge to anyone for any purpose. There is no indication up until now how many users will need to be supported simultaneously. The given situation may develop in such a way that it might become difficult to serve all registered users at the same times. In cases where limited resources on the Ntrip Broadcaster side (software restrictions, bandwidth limitation etc.) dictates, first priority in stream provision will be given to stream providers followed by re-broadcasting activities and real-time analysis centers while access to others might be temporarily denied.
- Once BNC has been started, many of its configuration options cannot be changed as long as it is stopped. See chapter 'Reread Configuration' for on-the-fly configuration exceptions.
- Drag and drop of configuration files is currently not supported on Mac OS X. On such system you have to start BNC via command line.

#### Looking Back

A basic function of BNC is streaming GNSS data over the open Internet using the Ntrip transport protocol. Employing IP streaming for satellite positioning goes back to the beginning of our century. Wolfgang Rupprecht has been the first person who developed TCP/IP server software under the acronym of DGPS-IP (Rupprecht 2000) and published it under GNU General Public License (GPL). While connecting marine beacon receivers to PCs with permanent access to the Internet he transmitted DGPS corrections in an RTCM format to support Differential GPS positioning over North America. With approximately 200 bits/sec the bandwidth requirement for disseminating beacon data was comparatively small. Each stream was transmitted over a unique combination of IP address and port. Websites informed about existing streams and corresponding receiver positions.

To cope with an increasing number of transmitting GNSS reference stations, the Federal Agency for Cartography and Geodesy (BKG) together with the Informatik Centrum Dortmund (ICD) in Germany developed a streaming protocol for satellite navigation data called 'Networked Transport of RTCM via Internet Protocol' (Ntrip). The protocol was built on top of the HTTP standard and included the provision of meta data describing the stream content. Any stream could now be globally transmitted over just one IP port: HTTP port 80. Stream availability and content details became part of the transport protocol. The concept was first published in 2003 (Weber and Honkala 2004, Weber et al. 2005a) and was based on three software components, namely an NtripServer pushing data from a reference station to an NtripCaster and an NtripClient pulling data from the stream splitting caster to support a rover receiver. (Note that from a socket-programmers perspective NtripServer and NtripClient both act as clients; only the NtripCaster operates as socket-server.) Ntrip could essentially benefit from Internet Radio developments. It was the ICECAST multimedia server, which provided the bases for BKG's 'Professional Ntrip Broadcaster' with software published first in 2003 and of course again as Open Source under GPL.

For BKG as a governmental agency, making Ntrip an Open Industry Standard has been an objective from the very beginning. The 'Radio Technical Commission for Maritime Services' (RTCM) accepted 'Ntrip Version 1' in 2004 as 'RTCM Recommended Standard' (Weber et al. 2005b). Nowadays there is almost no geodetic GNSS receiver which does not come with integrated NtripClient and NtripServer functionality as part of the firmware. Hundreds of NtripCaster implementations are operated world-wide for highly accurate satellite navigation through RTK networks. Thousands of reference stations upload observations via NtripServer to central computing facilities for any kind of NtripClient application. In 2011 'Ntrip Version 2' was released (RTCM SC-104 2011) which cleared and fixed some design problems and HTTP protocol violations. It also supports TCP/IP via SSL and adds optional communication over RTSP/RTP and UDP.

With the advent of Ntrip as an open streaming standard, BKG's interest turned towards taking advantage from free real-time access to GNSS observations. International Associations such as the IAG Reference Frame Sub Commissions for Africa (AFREF), Asia & Pacific (APREF), Europe (EUREF), North America (NAREF) Latin America & Caribbean (SIRGAS), and the International GNSS Service (IGS) maintain continental or even global GNSS networks with the majority of modern receivers supporting Ntrip stream upload. Through operating BKG's NtripCaster software, these networks became extremely valuable sources of real-time GNSS information. In 2005, this was the starting point for developing the 'BKG Ntrip Client' (BNC) as a multi-stream Open Source NtripClient that allows pulling hundreds of streams simultaneously from any number of NtripCaster installations world-wide. Decoding incoming RTCM streams and output observations epoch by epoch via IP port to feed a real-time GNSS network engine became BNC's first and foremost ability (Weber and Mervart 2009). Converting decoded streams to short high-rate RINEX files to assist near real-time applications became a welcome by-product right from the start of this development.

Adding real-time Precise Point Positioning (PPP) support to BNC began in 2010 as an important completion in view of developing an Open RTCM Standard for that. According to the State Space Representation (SSR) model, new Version 3 messages are proposed to provide e.g. satellite orbit and clock corrections and ionospheric corrections as well as biases for code and phase data. The ultimate goal for SSR standardization is to reach centimeter level accuracy within seconds as an alternative to Network RTK methods such as VRS, FKP, and MAC. Because of interoperability aspects, an Open Standard in this area is of particular interest for clients. Regarding stand-alone PPP in BNC, it is worth mentioning that the program is not and can never be in competition with a receiver manufacturer's proprietary solution. Only software or services that are part of a receiver firmware could have the potential of becoming a thread for commercial interests. However, implementing or not implementing an Open PPP approach in a firmware is and will always remain a manufacturer's decision.

Implementing some post processing capability is essential for debugging real-time software in case of problems. So certain real-time options in BNC were complemented to work offline through reading data from files. Moreover, beginning in 2012, the software was extended to support Galileo, BeiDou, and QZSS besides GPS and GLONASS. With that, the Open Source tool BNC could be used for RINEX Version 3 file editing, concatenation and quality checks, a post processing functionality demanded by the IGS Multi-GNSS Experiment and not really covered at that time by UNAVCO's famous TEQC program with its limitation on GPS.

The well-established, mature codebase is mostly written in C++ language. Its publication under GNU GPL is thought to be well-suited for test, validation and demonstration of new approaches in precise real-time satellite navigation when IP streaming is involved. Commissioned by a German governmental agency, the overall intention has been to push the development of RTCM Recommended Standards to the benefit of IAG institutions and services such as IGS and the interested public in general.

### 2. Settings Details

The general documentation approach is to create a separate chapter for each processing option in a sequence which follows the layout of BNC's Graphical User Interface (GUI). The advantage is that searching for help by means of the document's Table of Contents (TOC) is quite convenient. A rather comprehensive number of TOC entries is the accepted downside of this approach.

The following chapters describe how to set BNC program options. They explain the 'Top Menu Bar', the 'Settings Canvas' with the processing options, the content of the 'Streams Canvas' and 'Logging Canvas', and the 'Bottom Menu Bar'.

#### 2.1 Top Menu Bar

The top menu bar allows selecting a font for the BNC windows, save configured options, or quit the program execution. It also provides access to the program's documentation.

#### 2.1.1 File

The 'File' button lets you

- Select an appropriate font.
  Use smaller font size if the BNC main window exceeds the size of your screen.
- Reread and save selected options in configuration file.
  When using 'Reread & Save Configuration' while BNC is already processing data, some configuration options become immediately effective on-the-fly without interrupting uninvolved threads while all of them are saved on disk. See section 'Reread Configuration' for a list of on-the-fly changeable configuration options.
- Quit the BNC program.

#### 2.1.2 Help

The 'Help' button provides access to

- Help contents.
  You may keep the 'Help Contents' window open while configuring BNC.
- A 'Flow Chart' showing BNC linked to a real-time GNSS network engine such as RTNET.
- General information about BNC.
  Close the 'About BNC' window to continue working with BNC.

#### 2.2 Network

You may need to specify a proxy when running BNC in a protected network. You may also like to use the Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL) cryptographic protocols for secure Ntrip communication over the Internet.

#### 2.2.1 Proxy - Usage in a protected LAN

If you are running BNC within a protected Local Area Network (LAN), you might need to use a proxy server to access the Internet. Enter your proxy server IP and port number in case one is operated in front of BNC. If you do not know the IP and port of your proxy server, check the proxy server settings in your Internet browser or ask your network administrator. Without any entry, BNC will try to use the system proxies.

Note that IP streaming is often not allowed in a LAN. In this case you need to ask your network administrator for an appropriate modification of the local security policy or for the installation of a TCP relay to the Ntrip Broadcaster you need to access. If this is not possible, you might need to run BNC outside your LAN on a host that has unobstructed connection to the Internet.

#### 2.2.2 SSL - Transport Layer Security

Communication with an Ntrip Broadcaster over Secure Sockets Layer (SSL) as well as the download of RINEX skeleton files when available from HTTPS websites requires the exchange of client and/or server certificates. Specify the path to a directory where you save certificates on your system. You may like to check out http://software.rtcm-ntrip.org/wiki/Certificates for a list of known Ntrip Server certificates. You may also just try communication via SSL to check out whether this is supported by the involved Ntrip Broadcaster.

SSL communication may involve queries coming from the Ntrip Broadcaster or from a HTTPS website hosting RINEX skeletons. Such a query could show up under BNC's 'Log' tab especially when self-signed SSL certificates are used. Example:

       SSL Error
       Server Certificate Issued by:
       GNSS Data Center
       BKG (Bundesamt für Geodäsie und Kartographie)
       Cannot be verified

       The issuer certificate of a locally looked up certificate could not be found
       The root CA certificate is not trusted for this purpose
       No certificates could be verified

Queries should not be received by a client when a server uses official SSL certificates.

Tick 'Ignore SSL authorization errors' if you generally trust the server and do not want to be bothered with this. Note that SSL communication is usually done over port 443.

Figure 7: BNC's 'Network' panel configured to ignore eventually occurring SSL error messages

#### 2.3 General

The following defines general settings for BNC's logfile, file handling, reconfiguration on-the-fly, and auto-start.

#### 2.3.1 Logfile - optional

Records of BNC's activities are shown in the 'Log' tab on the bottom of the main window. These logs can be saved into a file when a valid path is specified in the 'Logfile (full path)' field. The logfile name will automatically be extended by a string '_YYMMDD' for the current date. This leads to series of daily logfiles when running BNC continuously. Message logs cover the communication status between BNC and the Ntrip Broadcaster as well as problems that may occur in the communication link, stream availability, stream delay, stream conversion etc. The time stamps within the 'Log' tab are given in UTC. The time stamps within the logfile are given in GPS Time. The default value for 'Logfile (full path)' is an empty option field, meaning that BNC logs will not be saved into a file.

The following is an example for the content of a logfile written by BNC when operated in Precise Point Positioning (PPP) mode:

    22-10-04 19:53:57 ========== Start BNC v2.13 (LINUX) ==========
    22-10-04 19:53:57 Panel 'PPP' active
    22-10-04 19:53:57 WTZR00DEU0: Get data in RTCM 3.x format
    22-10-04 19:53:57 BCEP00BKG0: Get data in RTCM 3.x format
    22-10-04 19:53:58 SSRA00BKG1: Get data in RTCM 3.x format
    22-10-04 19:53:58 Configuration read: 08_PPP.bnc, 3 stream(s)
    22-10-04 19:53:58 BCEP00BKG0: UNHEALTHY EPH G28 LNAV: 2022 10 04 20 00 00
    22-10-04 19:54:13 2022-10-04_19:53:59.000 WTZR00DEU0 X = 4075580.5340 Y = 931854.3984 Z = 4801568.4250 NEU:  -0.1623  +0.2450  +0.2991 TRP:  +2.1833  +0.0002
    22-10-04 19:54:13 2022-10-04_19:54:00.000 WTZR00DEU0 X = 4075580.5393 Y = 931854.4017 Z = 4801568.4126 NEU:  -0.1748  +0.2471  +0.2936 TRP:  +2.1833  +0.0002
    22-10-04 19:54:14 2022-10-04_19:54:01.000 WTZR00DEU0 X = 4075580.4979 Y = 931854.4015 Z = 4801568.3441 NEU:  -0.1891  +0.2560  +0.2153 TRP:  +2.1833  +0.0004
    22-10-04 19:54:14 2022-10-04_19:54:02.000 WTZR00DEU0 X = 4075580.4871 Y = 931854.4003 Z = 4801568.3157 NEU:  -0.1995  +0.2573  +0.1868 TRP:  +2.1833  +0.0007
    22-10-04 19:54:14 2022-10-04_19:54:03.000 WTZR00DEU0 X = 4075580.4698 Y = 931854.3966 Z = 4801568.3005 NEU:  -0.1961  +0.2575  +0.1637 TRP:  +2.1833  +0.0009
    22-10-04 19:54:14 2022-10-04_19:54:04.000 WTZR00DEU0 X = 4075580.4598 Y = 931854.3940 Z = 4801568.2881 NEU:  -0.1964  +0.2573  +0.1476 TRP:  +2.1833  +0.0010
    22-10-04 19:54:18 2022-10-04_19:54:05.000 WTZR00DEU0 X = 4075580.4625 Y = 931854.3971 Z = 4801568.2917 NEU:  -0.1966  +0.2597  +0.1525 TRP:  +2.1833  +0.0012
    22-10-04 19:54:18 2022-10-04_19:54:06.000 WTZR00DEU0 X = 4075580.4587 Y = 931854.3966 Z = 4801568.2912 NEU:  -0.1940  +0.2600  +0.1496 TRP:  +2.1833  +0.0014
    22-10-04 19:54:18 2022-10-04_19:54:07.000 WTZR00DEU0 X = 4075580.4539 Y = 931854.3931 Z = 4801568.2818 NEU:  -0.1960  +0.2577  +0.1389 TRP:  +2.1833  +0.0018
    22-10-04 19:54:18 2022-10-04_19:54:08.000 WTZR00DEU0 X = 4075580.4502 Y = 931854.3946 Z = 4801568.2757 NEU:  -0.1975  +0.2599  +0.1321 TRP:  +2.1833  +0.0021
    22-10-04 19:54:18 2022-10-04_19:54:09.000 WTZR00DEU0 X = 4075580.4478 Y = 931854.3958 Z = 4801568.2737 NEU:  -0.1973  +0.2617  +0.1293 TRP:  +2.1833  +0.0023
    ...

#### 2.3.2 Append Files - optional

When BNC is started, new files are created by default and existing files with the same name will be overwritten. However, users might want to append existing files following a restart of BNC, a system crash or a BNC crash. Tick 'Append files' to continue with existing files and keep what has been recorded so far. Note that option 'Append files' affects all types of files created by BNC.

#### 2.3.3 Reread Configuration - optional

When operating BNC online in 'no window' mode (command line option -nw), some configuration options can nevertheless be changed on-the-fly without interrupting the running process. For that, you force the program to reread parts of its configuration in pre-defined intervals from disk. Select '1 min', '1 hour', or '1 day' to let BNC reread on-the-fly changeable configuration options every full minute, hour, or day. This lets in-between edited options become effective without interrupting uninvolved threads.

Note that following configuration options saved on disk can be changed/edited on-the-fly while BNC is already processing data:

- 'mountPoints' to change the selection of streams to be processed, see section 'Streams'
- 'outWait' to change the 'Wait for full obs epoch' option, see section 'Feed Engine'
- 'outSampl' to change the 'Sampling' option, see section 'Feed Engine'
- 'outFile' to change the 'File' name where synchronized observations are saved in plain ASCII format

#### 2.3.4 Auto Start - optional

You may like to auto-start BNC at startup time in window mode with pre-assigned configuration options. This may be required e.g. immediately after booting your system. Tick 'Auto start' to supersede the usage of the 'Start' button. Make sure that you maintain a link to BNC for that in your Autostart directory (Windows systems) or call BNC in a script below directory /etc/init.d (Unix/Linux/Mac OS X systems).

See BNC's command line option '-nw' for an auto-start of BNC in 'no window' mode.

#### 2.3.5 Raw Output File - optional

BNC can save all data coming in through various streams in one daily file. The information is recorded in the specified 'Raw output file' in the received order and format. This feature allows a BNC user to run the PPP option offline with observations, Broadcast Corrections, and Broadcast Ephemeris being read from a previously saved file. It supports the offline repetition of a real-time situation for debugging purposes (Record & Replay functionality) and is not meant for post processing.

Data will be saved in blocks in the received format separated by ASCII time stamps like (example):

       2022-10-04T20:07:31 WTZR00DEU0 RTCM_3.3 202

This example block header tells you that 202 bytes were saved in the data block following this time stamp. The information in this block is encoded in RTCM Version 3 format, comes from mountpoint WTZR00DEU0 and was received at 20:07:31 GPS Time on 2022-10-04. BNC adds its own time stamps in order to allow the reconstruction of a recorded real-time situation.

The default value for 'Raw output file' is an empty option field, meaning that BNC will not save all raw data into one single daily file.

#### 2.4 RINEX Observations

Observations will be converted to RINEX if they come in either RTCM Version 2 or RTCM Version 3 format. Depending on the RINEX version and incoming RTCM message types, files generated by BNC may contain data from GPS, GLONASS, Galileo, BDS, SBAS, QZSS, and/or IRNSS. In case an observation type is listed in the RINEX header but the corresponding observation is unavailable, its value is set to zero '0.000' or left blank. Note that the 'RINEX TYPE' field in the RINEX Version 3 Observation file header is always set to 'M(MIXED)' or 'Mixed' even if the file only contains data from one system.

It is important to understand that converting RTCM streams to RINEX files requires a priori information on observation types for specifying a complete RINEX header. Regarding the RINEX Version 2 file header, BNC simply introduces all observation types defined in the Version 2 standard and later reports "0.000" for observations which are not received. However, following this approach is not possible for RINEX Version 3 files from RTCM Version 3 MSM streams because of the huge number of observation types, which might in principle show up. The solution implemented in BNC is to start with RINEX Version 3 observation type records from skeleton files (see section 'Skeleton Extension' and 'Skeleton Mandatory') and switch to a default selection of observation types when such file is not available or does not contain the required information.

Please note that RTCM Version 3 messages 1084 (MSM4) for GLONASS observations do not contain the GLONASS channel numbers. These observation messages can only be converted to RINEX when you add messages which include the channel numbers, such as the GLONASS ephemeris messages 1020. The GLONASS channel number is available as extended information within MSM5/7 messages.

The screenshot below shows an example setup of BNC when converting streams to RINEX. Streams are coming from Ntrip Broadcaster http://igs-ip.net:2101. Specifying a decoder string 'ZERO' would mean to not convert the affected stream but save its content as received. On Wed Oct 5 2022 that would result for the Mountpoint 'FFMJ00DEU0' into a file named 'FFMJ00DEU0_221005'.

Figure 8: BNC translating incoming RTCM Version 3 Observation streams to 15 min RINEX Version 4 Observation files

#### 2.4.1 RINEX Filenames

The RINEX filenames generated by BNC depend on the chosen RINEX format. The following convention holds in case of RINEX Version 3 and RINEX Version 4 filenames:

Filename Parameter | # Char. | Meaning
Name | 9 | Site, station and country code
S | 1 | Data source
Start Time | 11 | YYYYDDDHHMM
Period | 3 | File period
Obs. Freq. | 3 | Observation frequency
Content | 2 | Content type
Format | 3 | File format
Compression | 2-3 | Compression method (optional)

Examples (Figure 8) for Mixed RINEX Version 4 GNSS observation filenames, files containing 15 minutes of data, one observation every second, 'MO' standing for 'Mixed Observations':

       FFMJ00DEU_S_20222781400_15M_01S_MO.rnx
       CUT000AUS_S_20222781400_15M_01S_MO.rnx

Note that filename details are produced from the stream's mountpoint as well as corresponding BNC settings and meta data from the Ntrip Broadcaster source-table.

RINEX Version 2 filenames are derived from the first 4 characters of the corresponding stream's mountpoint (4-Char Station ID). For example, data from mountpoints FFMJ00DEU0 and CUT000AUS0 will have 15-minutes RINEX Observation files named

       FFMJ278O00.22O
       CUT0278O00.22O

The RINEX version 2 filneme convention can be summrized as follows:

       {4-Char-Station-ID}{ddd}{h}{mm}.{yy}O

where 'ddd' is the day of year, 'h' is a letter which corresponds to an hour long UTC time block, 'mm' is the starting minute within the hour. and 'yy' is the year.

#### 2.4.2 Directory - optional

Here you can specify the path to where the RINEX Observation files will be stored. If the specified directory does not exist, BNC will not create RINEX Observation files. Default value for 'Directory' is an empty option field, meaning that no RINEX Observation files will be written.

#### 2.4.3 File Interval - mandatory if 'Directory' is set

Select the length of the RINEX Observation file to be generated. The default value is 1 day.

#### 2.4.4 Sampling - mandatory if 'Directory' is set

Select the RINEX Observation sampling interval in seconds. A value of zero '0' tells BNC to store all received epochs into RINEX. This is the default value.

#### 2.4.5 Skeleton Extension - optional

Whenever BNC starts to generate RINEX Observation files (and then once every day at midnight), it first tries to retrieve information needed for RINEX headers from so-called public RINEX header skeleton files which are derived from sitelogs. An HTTP or HTTPS link to a directory containing these skeleton files may be available through data field number 7 of the affected NET record in the source-table. See https://igs.bkg.bund.de/root_ftp/IGS/station/rnxskl/BRUX00BEL.skl for an example of a public RINEX header skeleton file for EPN station Brussels. Note that the download of RINEX skeleton files from HTTPS websites requires the exchange of client and/or server certificates. Clarify 'SSL' options offered through panel 'Network' for details.

Sometimes public RINEX header skeleton files are not available, their content is not up to date, or you need to put additional/optional records in the RINEX header. For that, BNC allows using personal skeleton files that contain the header records you would like to include. You can derive a personal RINEX header skeleton file from the information given in an up to date sitelog. A file in the RINEX Observations 'Directory' with a 'Skeleton extension' suffix is interpreted by BNC as a personal RINEX header skeleton file for the corresponding stream.

When producing RINEX Observation files from mountpoints like 'BRUX00BEL0', 'WTZR_RTCM3', and 'BRUX0', the following skeleton filenames would be accepted

       BRUX00BEL.skl (9 char corresponding to RINEX version 3,4)
       WTZR_RTCM.skl (9 char corresponding to RINEX version 3,4)
       BRUX.skl (4 char corresponding to RINEX version 2)

if 'Skeleton extension' is set to 'skl'. As an alternative the basename is tried to use with lower cases as well.

Note the following regulations regarding personal RINEX header skeleton files: If such a file exists in the 'RINEX directory', the corresponding public RINEX header skeleton file is ignored. The RINEX header is generated solely from the content of the personal skeleton.

- Personal skeletons should contain a complete first header record of type 'RINEX VERSION / TYPE'
- They should then contain an empty header record of type 'PGM / RUN BY / DATE' which will be completed by BNC and included in the RINEX file header.
- They should further contain complete header records of type
  'MARKER NAME'
  'OBSERVER / AGENCY'
  'REC # / TYPE / VERS'
  'ANT # / TYPE'
  'APPROX POSITION XYZ'
  'ANTENNA: DELTA H/E/N'
  'WAVELENGTH FACT L1/2 for RINEX Version 2 files
  'SYS / # / OBS TYPES' for RINEX Version 3 files, will be ignored in Version 2 files
- They may contain any other optional complete header record as defined in the RINEX documentation.
- They should also contain an empty header record of type '# / TYPES OF OBSERV'. It will be used in RINEX Version 2 files and ignored in Version 3 files.
- BNC will include these lines in the final RINEX file header together with an additional 'COMMENT'-line describing the source of the stream.
- Personal skeletons must not contain a header record of type 'TIME OF FIRST OBS'
- They should finally contain an empty last header record of type 'END OF HEADER'

If neither a public nor a personal RINEX header skeleton file is available for BNC, a default header will be used.

The following is a skeleton example for a RINEX file:

                        OBSERVATION DATA    M                   RINEX VERSION / TYPE
    PORTIONS OF THIS HEADER GENERATED BY BKG AT 05-Oct-22 04:51 COMMENT
     FROM SITELOG CUT000AUS_20201020.log                        COMMENT
    OBS TYPES from www.igs-ip.net/CUT000AUS0                    COMMENT
    CUT000AUS                                                   MARKER NAME
    59945M001                                                   MARKER NUMBER
                        CUT                                     OBSERVER / AGENCY
    5023K67889          TRIMBLE NETR9       5.45                REC # / TYPE / VERS
    4928353386          TRM59800.00     SCIS                    ANT # / TYPE
     -2364337.2699  4870285.5624 -3360809.8398                  APPROX POSITION XYZ
            0.0000        0.0000        0.0000                  ANTENNA: DELTA H/E/N
    G   13 C1C L1C D1C S1C C2W L2W S2W C2X L2X S2X C5X L5X S5X  SYS / # / OBS TYPES
    R   13 C1C L1C D1C S1C C1P L1P S1P C2C L2C S2C C2P L2P S2P  SYS / # / OBS TYPES
    E   13 C1X L1X D1X S1X C7X L7X S7X C8X L8X S8X C5X L5X S5X  SYS / # / OBS TYPES
    J   10 C1C L1C D1C S1C C2X L2X S2X C5X L5X S5X              SYS / # / OBS TYPES
    C   10 C2I L2I D2I S2I C6I L6I S6I C7I L7I S7I              SYS / # / OBS TYPES
     22 R01  1 R02 -4 R03  5 R04  6 R05  1 R06 -4 R07  5 R08  6 GLONASS SLOT / FRQ #
        R09 -2 R10 -7 R11  0 R12 -1 R13 -2 R14 -7 R15  0 R17  4 GLONASS SLOT / FRQ #
        R18 -3 R19  3 R20  2 R21  4 R23  3 R24  2               GLONASS SLOT / FRQ #
                                                                END OF HEADER

#### 2.4.6 Skeleton Mandatory - optional

Tick check box 'Skeleton mandatory' in case you want that RINEX files are only produced when skeleton files are available for BNC. If no skeleton file is available for a particular source, then no RINEX observation file will be produced from the affected stream.

Note that a skeleton file contains RINEX header information such as receiver and antenna types. In case of stream conversion to RINEX Version 3, a skeleton file should also contain information on potentially available observation types. A missing skeleton file will force BNC to only save a default set of RINEX 3 observation types.

#### 2.4.7 Skeleton Directory - optional

Here you can specify the path, where local skeleton files are located. If no directory is specified, the path is assumed to where the RINEX Observation files will stored.

#### 2.4.8 Script - optional

Whenever a RINEX Observation file is saved, you might want to compress, copy or upload it immediately via FTP. BNC allows you to execute a script/batch file to carry out these operations. To do that, specify the full path to such script/batch file. BNC will pass the RINEX Observation file path to the script as a command line parameter (%1 on Windows systems, $1 on Unix/Linux/Mac OS X systems).

The triggering event for calling the script or batch file is the end of a RINEX Observation file 'Interval'. If that is overridden by a stream outage, the triggering event is the stream reconnection.

As an alternative to initiating file uploads through BNC, you may like to call an upload script or batch file through your crontable or Task Scheduler (independent from BNC) once every one or two minutes after the end of each RINEX file 'Interval'.

#### 2.4.9 Version 3 and 4 - optional

Currently, the default format for RINEX Observation files is RINEX Version 3. RINEX version 4 can be chosen as well. The resulting observation files are backward compatible to RINEX version 3.

Note, that it is possible to force an RTCM Version 2 stream to be saved in RINEX Version 3 file format. However, this is not recommended, because such stream cannot be precisely mapped to RINEX Version 3 as the required information on tracking modes (observation attributes) is not part of RTCM Version 2.

#### 2.4.10 Version 2 - optional

GNSS observation data are generally hold available within BNC according to attributes as defined in RINEX Version 3 or 4. These attributes describe the tracking mode or channel when generating the observation signals. Capital letters specifying signal generation attributes are e.g. A, B, C, D, E, I, L, M, N, P, Q, S, W, X, Y, or Z, see RINEX Version 3 and 4 documentation. Nevertheless, there are two applications where the program can be setup to produce data files in RINEX Version 2.11 format:

1. When saving the content of incoming observation streams in RINEX Version 2 files as described in this section.
2. When editing or concatenating RINEX version 3/4 files to save them in Version 2 format, see section on 'RINEX Editing & QC'.

Select RINEX 'Version 2' if you would like to save RTCM Version 3 observation streams in RINEX Version 2 format. As the Version 2 format ignores signal generation attributes, BNC is forced to somehow map RINEX Version 3/4 to RINEX Version 2 although this cannot be done in one-to-one correspondence. Hence we introduce a 'Signal priority' list of attributes (characters, forming a string) for mapping Version 3/4 to Version 2.

Signal priorities can be specified as equal for all systems, as system specific or as system and frequency specific. For example:

- 'CWPX_?' (General signal priorities valid for all GNSS)
- 'I:ABCX' (System specific signal priorities for IRNSS)
- 'G:12&PWCSLX G:5&IQX R:12&PC R:3&IQX' (System and frequency specific signal priorities)

The default 'Signal priority' list is defined as follows:

- 'G:12&PWCSLX G:5&IQX R:12&PC R:3&IQX R:46&ABX E:16&BCXZ E:578&IQX J:1&SLXCZ J:26&SLX J:5&IQX C:267&IQX C:18&DPX I:ABCX S:1&C S:5&IQX'

As an example the 'Signal priority' of 'CWPX_?' is explained in more detail:

- Signals with attribute 'C' enjoy the highest priority. If such a RINEX Version 3/4 observation becomes available, it is presented as RINEX Version 2 observation if that is the format you wish to see. Observations with other attributes are being ignored.
- If no signal with 'C' attribute is available but we have an observation with 'W' attribute, BNC presents that one as RINEX Version 2 observation and ignores all observations with other attributes. The same applies mutatis mutandis to observations with P and X attributes.
- If no signal with 'C', 'W', 'P', or 'X' attribute is available but a signal with undefined generation attribute (underscore character, '_') exists, BNC presents that one as RINEX Version 2 observation. Note that observation attributes should actually always be available in RINEX Version 3/4. Hence the underscore character makes only sense in a few very special cases.
- If no signal with 'C', 'W', 'P', 'X', or '_' generation attribute exists then the question mark '?' tells BNC to present the first of any other appearing signal as RINEX Version 2 observation.

You may like to specify your own 'Signal priority' string(s) for producing RINEX Version 2 files.

#### 2.5 RINEX Ephemeris

Broadcast Ephemeris can be saved in RINEX Navigation files when received e.g. via RTCM Version 3 message types:

- 1019 (GPS) or
- 1020 (GLONASS) or
- 1041 (IRNSS) or
- 1042 (BDS/BeiDou) or
- 1043 (SBAS) or
- 1044 (QZSS) or
- 1045 (Galileo F/NAV) or
- 1046 (Galileo I/NAV).

The filename convention follows the details given in section 'RINEX Filenames' except that the first four characters are 'BRDC'.

Regarding RINEX Version 3/4 you will find all ephemeris data for GPS, GLONASS, Galileo, SBAS, QZSS, BDS, and IRNSS gathered in one Navigation file.

The following is an example for a RINEX Version 3/4 Navigation filename. The file contains one hour's data. 'MN' stands for 'Multi Constellation Navigation' data.

       BRDC00WRD_S_20222791000_01H_MN.rnx

For RINEX Version 2 Navigation files the last character is 'N' or 'G' for GPS or GLONASS ephemeris in two separate files.

Note further that BNC will ignore incorrect or outdated Broadcast Ephemeris data, leaving a note 'WRONG EPHEMERIS' or 'OUTDATED EPHEMERIS' in the logfile.

#### 2.5.1 Directory - optional

Specify a path for saving Broadcast Ephemeris data in RINEX Navigation files. If the specified directory does not exist, BNC will not create RINEX Navigation files. Default value for Ephemeris 'Directory' is an empty option field, meaning that no RINEX Navigation files will be created.

#### 2.5.2 Interval - mandatory if 'Directory' is set

Select the length of RINEX Navigation files. The default value is '1 day'.

#### 2.5.3 Port - optional

BNC can output Broadcast Ephemeris in RINEX Version 3 format on your local host (IP 127.0.0.1) through an IP 'Port'. Specify an IP port number to activate this function. The default is an empty option field, meaning that no ASCII ephemeris output via IP port is generated.

The source code for BNC comes with an example Perl script 'test_tcpip_client.pl' that allows you to read BNC's ephemeris ASCII output from the IP port.

#### 2.5.4 Version - optional

Default format for RINEX Navigation files containing Broadcast Ephemeris is RINEX Version 3, saving the ephemeris data in RINEX Version 3.05. Select 'Version 2' if you want to save the ephemeris data in RINEX Version 2.11 format. Select 'Version 4' if you want to save the ephemeris data in RINEX Version 4.x format.

Note that the here choosen Version concerns the Broadcast Ephemeris output through IP port as well.

#### 2.6 RINEX Editing & QC

Besides stream conversion from RTCM to RINEX, BNC allows editing RINEX files or concatenate their content. RINEX Observation and Navigation files can be handled. BNC can also carry out a RINEX file Quality Check. In summary and besides Stream Translation, this functionality in BNC covers

- File Editing and concatenation
- File Quality Check

- Multipath analysis sky plots
- Signal-to-noise ratio sky plots
- Satellite availability plots
- Satellite elevation plots
- PDOP plots

and hence follows UNAVCO's famous TEQC program (see Estey and Meertens 1999). The remarkable thing about BNC in this context is that it supports RINEX Version 3 under GNU General Public License with full GUI support and graphics output.

#### 2.6.1 Action - optional

Select an action. Options are 'Edit/Concatenate' and 'Analyze'.

- Select 'Edit/Concatenate' if you want to edit RINEX file content according to options specified under 'Set Edit Options' or if you want to concatenate several RINEX files.
- Select 'Analyze' if you are interested in a quality check of your RINEX file content.

#### 2.6.2 Input Files - mandatory

Specify full path to input RINEX Observation file(s), and
specify full path to input RINEX Navigation file(s).

When specifying several input files, BNC will concatenate their contents. In case of RINEX Observation input files with different observation type header records, BNC will output only one set of adjusted observation type records in the RINEX header which fits to the whole file content.

#### 2.6.3 Output Files - optional if 'Action' is set to 'Edit/Concatenate'

If 'Edit/Concatenate' is selected, specifying the full path to output RINEX Observation file(s) and specifying the full path to output RINEX Navigation file(s) is optional. Default are empty option fields, meaning that no RINEX files will be saved on disk.

#### 2.6.4 Logfile - optional

Specify the name of a logfile to save information on RINEX file Editing/Concatenation or Analysis. Default is an empty option field, meaning that no logfile will be saved.

Note that logfiles from analyzing RINEX files may become quite large. Hence, BNC provides an option 'Summary only' to limit logfile content to some essential information in case 'Action' is set to 'Analyze'. The following is an example for a RINEX quality check analysis logfile:

    QC Format Version  : 1.1

    Navigation File(s) : MAO000USA_R_20221720000_01D_MN.rnx
    Ephemeris          : 1776 OK   3617 UNHEALTHY   116 WRONG
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH G09 LNAV: 2022 06 21 04 00 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH G09 LNAV: 2022 06 21 06 00 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH G09 LNAV: 2022 06 21 08 00 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH J07 LNAV: 2022 06 21 07 00 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH J07 LNAV: 2022 06 21 08 00 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH G09 LNAV: 2022 06 21 10 00 00
    ..
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C35 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C26 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C44 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C24 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C21 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C12 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH C40 D1  : 2022 06 21 23 00 14
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E11 FNAV: 2022 06 21 22 50 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH G08 LNAV: 2022 06 21 23 59 44
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E11 FNAV: 2022 06 21 23 00 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E11 FNAV: 2022 06 21 23 10 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E11 FNAV: 2022 06 21 23 20 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E11 FNAV: 2022 06 21 23 30 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E25 FNAV: 2022 06 21 23 30 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E11 FNAV: 2022 06 21 23 40 00
                         MAO000USA_R_20221720000_01D_MN.rnx : WRONG EPH E25 FNAV: 2022 06 21 23 40 00

    Observation File   : MAO000USA_R_20221720000_01D_30S_MO.rnx
    RINEX Version      : 4.00
    Marker Name        : MAO0
    Marker Number      : 40445M005
    Receiver           : SEPT POLARX5
    Antenna            : LEIAR25.R3      LEIT
    Position XYZ       :  -5466067.2677  -2404332.8007   2242123.7442
    Antenna dH/dE/dN   :   0.0000   0.0000   0.0000
    Start Time         : 2022-06-21 00.00.00.0
    End Time           : 2022-06-21 23.59.30.0
    Interval           : 30 sec
    Observation Types C: C1P L1P D1P S1P C5P L5P D5P S5P C2I L2I D2I S2I C7I L7I D7I S7I C6I L6I D6I S6I C7D L7D D7D S7D
    Observation Types E: C1C L1C D1C S1C C6C L6C D6C S6C C5Q L5Q D5Q S5Q C7Q L7Q D7Q S7Q C8Q L8Q D8Q S8Q
    Observation Types G: C1C L1C D1C S1C C1W S1W C2W L2W D2W S2W C2L L2L D2L S2L C5Q L5Q D5Q S5Q C1L L1L D1L S1L
    Observation Types I: C5A L5A D5A S5A
    Observation Types J: C1C L1C D1C S1C C2L L2L D2L S2L C5Q L5Q D5Q S5Q C1L L1L D1L S1L C1Z L1Z D1Z S1Z C5P L5P D5P S5P
    Observation Types R: C1C L1C D1C S1C C1P L1P D1P S1P C2P L2P D2P S2P C2C L2C D2C S2C
    Observation Types S: C1C L1C D1C S1C C5I L5I D5I S5I
    Analysed GNSS      : 4    C E G J

      C: Satellites: 42
      C: Signals   : 6    1P 2I 5P 6I 7D 7I

          C:   1P: Observations      :  28217
          C:   1P: Slips (file+found):       60 +      22
          C:   1P: Gaps              :      147
          C:   1P: Mean SNR          :     43.9
          C:   1P: Mean Multipath    :     0.60

          C:   2I: Observations      :  43725
          C:   2I: Slips (file+found):      124 +      32
          C:   2I: Gaps              :      209
          C:   2I: Mean SNR          :     44.8
          C:   2I: Mean Multipath    :     0.66

          C:   5P: Observations      :  28373
          C:   5P: Slips (file+found):       52 +       7
          C:   5P: Gaps              :      100
          C:   5P: Mean SNR          :     43.5
          C:   5P: Mean Multipath    :     0.26

          C:   6I: Observations      :  43887
          C:   6I: Slips (file+found):       95 +      15
          C:   6I: Gaps              :      156
          C:   6I: Mean SNR          :     44.6
          C:   6I: Mean Multipath    :     0.29

          C:   7D: Observations      :  30073
          C:   7D: Slips (file+found):       45 +      10
          C:   7D: Gaps              :       28
          C:   7D: Mean SNR          :     44.1
          C:   7D: Mean Multipath    :     0.28

          C:   7I: Observations      :  11450
          C:   7I: Slips (file+found):       23 +       0
          C:   7I: Gaps              :       16
          C:   7I: Mean SNR          :     43.0
          C:   7I: Mean Multipath    :     0.00

      E: Satellites: 27
      E: Signals   : 5    1C 5Q 6C 7Q 8Q

          E:   1C: Observations      :  28931
          E:   1C: Slips (file+found):       49 +       6
          E:   1C: Gaps              :       83
          E:   1C: Mean SNR          :     42.7
          E:   1C: Mean Multipath    :     0.43

          E:   5Q: Observations      :  27473
          E:   5Q: Slips (file+found):       34 +       6
          E:   5Q: Gaps              :       62
          E:   5Q: Mean SNR          :     43.5
          E:   5Q: Mean Multipath    :     0.22

          E:   6C: Observations      :  27564
          E:   6C: Slips (file+found):       40 +       9
          E:   6C: Gaps              :       77
          E:   6C: Mean SNR          :     45.5
          E:   6C: Mean Multipath    :     0.39

          E:   7Q: Observations      :  27504
          E:   7Q: Slips (file+found):       35 +       7
          E:   7Q: Gaps              :       55
          E:   7Q: Mean SNR          :     44.2
          E:   7Q: Mean Multipath    :     0.25

          E:   8Q: Observations      :  27099
          E:   8Q: Slips (file+found):       48 +       9
          E:   8Q: Gaps              :       35
          E:   8Q: Mean SNR          :     47.1
          E:   8Q: Mean Multipath    :     0.08

      G: Satellites: 32
      G: Signals   : 6    1C 1L 1W 2L 2W 5Q

          G:   1C: Observations      :  33608 (   35429)    94.86 %
          G:   1C: Slips (file+found):      120 +      40
          G:   1C: Gaps              :      159
          G:   1C: Mean SNR          :     43.8
          G:   1C: Mean Multipath    :     0.56

          G:   1L: Observations      :   4975 (   35429)    14.04 %
          G:   1L: Slips (file+found):       17 +       5
          G:   1L: Gaps              :       17
          G:   1L: Mean SNR          :     44.0
          G:   1L: Mean Multipath    :     0.54

          G:   1W: Observations      :  32785 (   35429)    92.54 %
          G:   1W: Slips (file+found):        0 +      41
          G:   1W: Gaps              :       83
          G:   1W: Mean SNR          :     33.5
          G:   1W: Mean Multipath    :     0.55

          G:   2L: Observations      :  24939 (   35429)    70.39 %
          G:   2L: Slips (file+found):       81 +      26
          G:   2L: Gaps              :       95
          G:   2L: Mean SNR          :     41.4
          G:   2L: Mean Multipath    :     0.49

          G:   2W: Observations      :  32785 (   35429)    92.54 %
          G:   2W: Slips (file+found):      110 +      44
          G:   2W: Gaps              :       83
          G:   2W: Mean SNR          :     33.5
          G:   2W: Mean Multipath    :     0.32

          G:   5Q: Observations      :  17026 (   35429)    48.06 %
          G:   5Q: Slips (file+found):       41 +       8
          G:   5Q: Gaps              :       47
          G:   5Q: Mean SNR          :     46.2
          G:   5Q: Mean Multipath    :     0.26

      J: Satellites: 4
      J: Signals   : 6    1C 1L 1Z 2L 5P 5Q

          J:   1C: Observations      :   9433 (    9493)    99.37 %
          J:   1C: Slips (file+found):       64 +       7
          J:   1C: Gaps              :       14
          J:   1C: Mean SNR          :     38.0
          J:   1C: Mean Multipath    :     0.71

          J:   1L: Observations      :   9438 (    9493)    99.42 %
          J:   1L: Slips (file+found):       14 +      10
          J:   1L: Gaps              :       10
          J:   1L: Mean SNR          :     38.9
          J:   1L: Mean Multipath    :     0.58

          J:   1Z: Observations      :   9428 (    9493)    99.32 %
          J:   1Z: Slips (file+found):       20 +       7
          J:   1Z: Gaps              :       16
          J:   1Z: Mean SNR          :     40.6
          J:   1Z: Mean Multipath    :     0.61

          J:   2L: Observations      :   9435 (    9493)    99.39 %
          J:   2L: Slips (file+found):       12 +       9
          J:   2L: Gaps              :       10
          J:   2L: Mean SNR          :     38.9
          J:   2L: Mean Multipath    :     0.58

          J:   5P: Observations      :   9443 (    9493)    99.47 %
          J:   5P: Slips (file+found):       12 +      11
          J:   5P: Gaps              :        8
          J:   5P: Mean SNR          :     36.4
          J:   5P: Mean Multipath    :     0.18

          J:   5Q: Observations      :   9457 (    9493)    99.62 %
          J:   5Q: Slips (file+found):       12 +      11
          J:   5Q: Gaps              :        7
          J:   5Q: Mean SNR          :     41.4
          J:   5Q: Mean Multipath    :     0.13

    > 2022 06 21 00 00  0.0000000 41  0.6
    G08   0.00    0.00   9  L1C .. 44.1  C1C  . 0.58  C1W  . 0.59  L2W .. 40.6  C2W  . 0.77  L2L .. 37.3  C2L  . 0.74  L5Q .. 45.3  C5Q  . 0.33
    G10  32.29   79.31   9  L1C .. 49.6  C1C  . 0.16  C1W  . 0.16  L2W .. 44.0  C2W  . 0.09  L2L .. 48.2  C2L  . 0.11  L5Q .. 51.6  C5Q  . 0.09
    G16  54.18 -127.22   5  L1C .. 47.1  C1C  . 0.21  C1W  . 0.21  L2W .. 39.4  C2W  . 0.10
    G21  15.13  -68.49   5  L1C .. 41.8  C1C  . 0.53  C1W  . 0.53  L2W .. 25.6  C2W  . 0.27
    G22  26.49  158.25   5  L1C .. 44.6  C1C  . 0.27  C1W  . 0.27  L2W .. 30.1  C2W  . 0.29
    G23   0.00    0.00  11  L1C .. 45.3  C1C  . 0.33  C1W  . 0.33  L2W .. 33.9  C2W  . 0.17  L2L .. 42.5  C2L  . 0.24  L5Q .. 46.3  C5Q  . 0.25  L1L .. 45.7  C1L  . 0.27
    G26   0.00    0.00   9  L1C .. 46.7  C1C  . 0.28  C1W  . 0.29  L2W .. 36.8  C2W  . 0.09  L2L .. 43.7  C2L  . 0.21  L5Q .. 48.6  C5Q  . 0.10
    G27   0.00    0.00   9  L1C .. 48.8  C1C  . 0.23  C1W  . 0.23  L2W .. 43.4  C2W  . 0.17  L2L .. 48.2  C2L  . 0.15  L5Q .. 51.9  C5Q  . 0.10
    G31   0.00    0.00   7  L1C .. 35.7  C1C  . 4.35  C1W  . 4.31  L2W .. 18.4  C2W  . 4.31  L2L s. 31.1  C2L  . 0.00
    G32   0.00    0.00   9  L1C .. 49.2  C1C  . 0.32  C1W  . 0.32  L2W .. 39.9  C2W  . 0.15  L2L .. 44.6  C2L  . 0.16  L5Q .. 48.0  C5Q  . 0.09
    E02  43.91 -107.45  10  L1C .. 47.6  C1C  . 0.27  L6C .. 50.3  C6C  . 0.23  L5Q .. 48.5  C5Q  . 0.11  L7Q .. 48.8  C7Q  . 0.14  L8Q .. 51.7  C8Q  . 0.02
    E03   2.45 -161.42  10  L1C .. 37.7  C1C  . 0.74  L6C .. 37.4  C6C  . 0.48  L5Q .. 36.9  C5Q  . 0.14  L7Q .. 37.6  C7Q  . 0.18  L8Q .. 40.3  C8Q  . 0.16
    E04   8.83   44.72   7  C1C  . 0.00  C6C  . 0.00  L5Q .. 28.5  C5Q  . 0.00  C7Q  . 0.00  L8Q .. 31.2  C8Q  . 0.00
    E05  37.64  160.08  10  L1C .. 46.5  C1C  . 0.13  L6C .. 49.7  C6C  . 0.12  L5Q .. 47.0  C5Q  . 0.12  L7Q .. 47.5  C7Q  . 0.10  L8Q .. 50.3  C8Q  . 0.03
    E09  42.44   89.19  10  L1C .. 47.7  C1C  . 0.20  L6C .. 50.7  C6C  . 0.13  L5Q .. 48.1  C5Q  . 0.09  L7Q .. 48.9  C7Q  . 0.19  L8Q .. 51.5  C8Q  . 0.04
    E11  20.61   64.05  10  L1C .. 41.7  C1C  . 0.14  L6C .. 42.8  C6C  . 0.14  L5Q .. 39.0  C5Q  . 0.14  L7Q .. 39.2  C7Q  . 0.12  L8Q .. 42.1  C8Q  . 0.03
    E25  29.05 -169.12  10  L1C .. 44.2  C1C  . 0.36  L6C .. 47.6  C6C  . 0.26  L5Q .. 45.0  C5Q  . 0.13  L7Q .. 46.0  C7Q  . 0.20  L8Q .. 48.5  C8Q  . 0.07
    E30  18.32  -53.65  10  L1C .. 42.8  C1C  . 0.34  L6C .. 46.1  C6C  . 0.37  L5Q .. 42.7  C5Q  . 0.26  L7Q .. 43.5  C7Q  . 0.32  L8Q .. 46.1  C8Q  . 0.03
    E34  26.84  -52.94  10  L1C .. 45.5  C1C  . 0.36  L6C .. 46.7  C6C  . 0.59  L5Q .. 44.1  C5Q  . 0.22  L7Q .. 44.6  C7Q  . 0.21  L8Q .. 47.4  C8Q  . 0.05
    E36  44.38   10.32  10  L1C .. 47.1  C1C  . 0.23  L6C .. 50.4  C6C  . 0.14  L5Q .. 48.4  C5Q  . 0.18  L7Q .. 49.1  C7Q  . 0.13  L8Q .. 51.7  C8Q  . 0.04
    J02  25.68  -71.42  12  L1C .. 43.6  C1C  . 0.60  L2L .. 40.0  C2L  . 0.83  L5Q .. 44.4  C5Q  . 0.06  L1L .. 43.6  C1L  . 0.71  L1Z .. 43.4  C1Z  . 0.64  L5P .. 40.8  C5P  . 0.09
    J03  18.88  -66.71  12  L1C .. 41.0  C1C  . 0.45  L2L .. 40.3  C2L  . 0.58  L5Q .. 42.9  C5Q  . 0.17  L1L .. 41.7  C1L  . 0.49  L1Z .. 41.4  C1Z  . 0.47  L5P .. 39.4  C5P  . 0.17
    J04   6.08 -127.48  12  L1C .. 39.3  C1C  . 1.18  L2L .. 38.2  C2L  . 1.45  L5Q .. 39.2  C5Q  . 0.59  L1L .. 38.7  C1L  . 1.31  L1Z .. 40.4  C1Z  . 1.21  L5P .. 35.0  C5P  . 0.60
    J07   3.70  -94.81  11  C1C  . 0.51  L2L .. 37.0  C2L  . 0.20  L5Q .. 39.5  C5Q  . 0.09  L1L .. 32.7  C1L  . 0.21  L1Z .. 38.9  C1Z  . 0.25  L5P .. 30.9  C5P  . 0.16
    C01  20.30 -102.21   6  L2I .. 41.8  C2I  . 0.00  L7I .. 42.6  C7I  . 0.00  L6I .. 40.1  C6I  . 0.00
    C04  35.59 -109.87   6  L2I .. 44.5  C2I  . 0.00  L7I .. 45.4  C7I  . 0.00  L6I .. 44.6  C6I  . 0.00
    C11  18.91  -42.10   6  L2I .. 39.0  C2I  . 0.00  L7I .. 46.1  C7I  . 0.00  L6I .. 44.6  C6I  . 0.00
    C12  51.55    8.60   6  L2I .. 48.5  C2I  . 0.00  L7I .. 51.5  C7I  . 0.00  L6I .. 50.9  C6I  . 0.00
    C14   7.32 -150.82   6  L2I .. 37.8  C2I  . 0.00  L7I .. 40.9  C7I  . 0.00  L6I .. 41.4  C6I  . 0.00
    C21  75.79  138.30  10  L1P .. 49.0  C1P  . 0.14  L5P .. 51.9  C5P  . 0.06  L2I .. 50.8  C2I  . 0.25  L6I .. 52.5  C6I  . 0.08  L7D .. 51.0  C7D  . 0.07
    C22  36.50   44.63  10  L1P .. 47.4  C1P  . 0.30  L5P .. 47.4  C5P  . 0.16  L2I .. 49.6  C2I  . 0.26  L6I .. 49.9  C6I  . 0.25  L7D .. 47.3  C7D  . 0.21
    C24  16.27 -139.62  10  L1P .. 43.9  C1P  . 0.74  L5P .. 42.8  C5P  . 0.12  L2I .. 44.7  C2I  . 0.71  L6I .. 43.5  C6I  . 0.16  L7D .. 42.6  C7D  . 0.19
    C25   8.87  -85.45  10  L1P .. 38.0  C1P  . 1.84  L5P .. 40.3  C5P  . 0.29  L2I .. 41.7  C2I  . 1.50  L6I .. 41.5  C6I  . 0.37  L7D .. 39.8  C7D  . 0.35
    C26   4.25  177.77  10  L1P .. 40.0  C1P  . 0.75  L5P .. 37.8  C5P  . 0.28  L2I .. 41.7  C2I  . 0.66  L6I .. 40.5  C6I  . 0.22  L7D .. 37.7  C7D  . 0.28
    C34  36.24  -28.48  10  L1P .. 46.7  C1P  . 0.36  L5P .. 42.5  C5P  . 0.23  L2I .. 48.9  C2I  . 0.44  L6I .. 48.1  C6I  . 0.21  L7D .. 42.3  C7D  . 0.38
    C35  16.68  103.11  10  L1P .. 41.8  C1P  . 0.44  L5P .. 41.5  C5P  . 0.20  L2I .. 43.3  C2I  . 0.34  L6I .. 43.0  C6I  . 0.19  L7D .. 40.9  C7D  . 0.21
    C40  10.26  -34.76  10  L1P .. 42.4  C1P  . 0.36  L5P .. 37.4  C5P  . 0.32  L2I .. 43.1  C2I  . 0.45  L6I .. 39.4  C6I  . 0.54  L7D .. 38.4  C7D  . 0.31
    C42  30.61 -156.42  10  L1P .. 46.0  C1P  . 0.34  L5P .. 46.6  C5P  . 0.17  L2I .. 47.7  C2I  . 0.33  L6I .. 48.1  C6I  . 0.08  L7D .. 46.1  C7D  . 0.14
    C44  53.90   52.53  10  L1P .. 48.1  C1P  . 0.18  L5P .. 49.4  C5P  . 0.11  L2I .. 50.9  C2I  . 0.34  L6I .. 50.9  C6I  . 0.15  L7D .. 48.9  C7D  . 0.10
    C57   0.00    0.00   4  L2I .. 48.1  C2I  . 0.00  L6I .. 48.2  C6I  . 0.00
    C59  15.79 -100.68   6  L2I .. 43.8  C2I  . 0.00  L6I .. 41.7  C6I  . 0.00  L7D .. 41.5  C7D  . 0.00
    > 2022 06 21 00 00 30.0000000 41  0.6
    ...

The epoch-specific output

Each 'Epoch Record' contains 9 parameters. Example:

    > 2022 06 21 00 00 30.0000000 49  0.5

Their meaning is as follows:

- Special character '>' is the first character in each 'Epoch Record' (as we have it in RINEX Version 3/4)
- Year, GPS time
- Month, GPS time
- Day, GPS time
- Hour, GPS time
- Minute, GPS time
- Second, GPS time
- Number of satellites
- PDOP value

Each of the 'Satellite Records' in such an epoch block carries information for one specific satellite. Example:

    E05  37.64  160.08  10  L1C .. 46.5  C1C  . 0.13  L6C .. 49.7  C6C  . 0.00  L5Q .. 47.0  C5Q  . 0.12  L7Q .. 47.5  C7Q  . 0.10  L8Q .. 50.3  C8Q  . 0.00

A satellite-specific line starts with:

- GNSS Indicator and Satellite Vehicle Pseudo Random Number
- Elevation [°]
- Azimuth [°]
- Number of observations types

An observation type block, for example

    L1C .. 46.5

or

    C1C  . 0.13

contains the RINEX Version 3/4 observation code and

- for a carrier phase observation:

- two characters, where 's' means cycle slip, 'g' means gap and '.' means OK
- signal-to-noise ratio SNR [dBHz]

- for a code observation:

- two characters: the first one (for slips) is empty, 'g' means gap and '.' means OK
- multipath standard deviation [m]

With respect to the summary note, that in addition to cycle slips recorded in the RINEX 'file', cycle slips identified by BNC are reported as 'found'.

#### 2.6.5 Plots for Signals - mandatory if 'Action' is set to 'Analyze'

BNC can produce plots for multipath, signal-to-noise ratio, satellite availability, satellite elevation, and PDOP values. The 'Plots for signals' option lets you exactly specify the observation signals to be used for that and also enables the plot production. You can specify

- the navigation system (C = BDS, E = Galileo, G = GPS, I = IRNSS, J = QZSS, R = GLONASS, S = SBAS),
- the band/frequency, and
- the attribute as defined in RINEX Version 3/4.

Specifications for band/frequency and attribute must be separated by ampersand character '&'.

Specifications for each navigation system must be separated by blank character ' '.

Default is 'G:1&2&5 R:1&2&3 E:1&7 C:2&6 J:1&2 I:5&9 S:1&5'. Specifying an empty option string would be overruled by this default.

Examples for the 'Plots for signals' option:

- G:1&2&5 E:1&7 (Plots will be based on GPS observations on 1st, 2nd and 5th frequency as well as on Galileo observations on 1st and 7th frequency.)
- G:1C&5X (Plots will be based on GPS observations on the 1st frequency in 'C' tracking mode andand on the 5th frequency in 'X' tracking mode.)
- C:2I&6I (Plots will be based on BDS observations on the 2th and on the 6th frequency; both in 'I' tracking mode.)

An example configuration with plot results can be seen below.

Figure 9: Example for creating RINEX quality check analysis graphics output with BNC

Figure 10: Example for satellite availability, elevation and PDOP plots as a result of a RINEX quality check analysis with BNC

Figure 11: Sky plot examples for multipath, part of RINEX quality check analysis with BNC

Figure 12: Sky plot examples for signal-to-noise ratio, part of RINEX quality check analysis with BNC

#### 2.6.6 Directory for Plots - optional if 'Action' is set to 'Analyze'

If 'Analyze' is selected, specifying the path to a directory where plot files will be saved is optional. Filenames will be composed from the RINEX input filename(s) plus suffix 'png' to indicate the plot file format in use. Default is an empty option field, meaning that plots will not be saved on disk.

#### 2.6.7 Set Edit Options - mandatory if 'Action' is set to 'Edit/Concatenate'

Once the 'Edit/Concatenate' action is selected, you have to 'Set Edit Options'. BNC lets you specify the RINEX version, a signal priority list when mapping RINEX Version 3/4 to Version 2, the sampling interval, begin and end of file, operator, observation types, comment lines, and marker, antenna, receiver details. Note that some of the specifications for editing and concatenation are only meaningful for RINEX Observation files but not for RINEX Navigation files.

A note on converting RINEX Version 3 to RINEX Version 2 and vice versa:

- The RINEX Version 2 format ignores signal generation attributes. Therefore, when converting RINEX Version 3/4 to Version 2 Observation files, BNC is forced to somehow map signals with attributes to signals without attributes although this cannot be done in one-to-one correspondence. Hence we introduce a 'Version 2 Signal Priority' list of attributes (characters, forming a string) for mapping Version 3/4 to Version 2, see details in section 'RINEX Observations/Version 2'.
- Converting RINEX Version 2 to Version 3/4 Observation files is not recommended because the attribute in the observation code (last character out of the 3-character) is left blank if unknown. This is a compromise, which is not in accordance with the RINEX Version 3/4 documentation.

Optionally you may specify a 'RUN BY' string to be included in the emerging new RINEX file header. Default is an empty option field, meaning the operator's ID is automatically used as 'RUN BY' string.

You can specify a list of observation codes in field 'Use Obs. Types' to limit the output file content to specific observation codes. GNSS system characters in that list are followed by a colon and a 2- or 3-Character observation code. A 2-Character observation code would mean that all available tracking modes of the affected observation type and frequency will be accepted as part of the RINEX output file. Observation codes are separated by a blank character. Default is an empty option field, meaning that any input observation code will become part of the RINEX output file.

Specifying comment line text to be added to the emerging new RINEX file header is another option. Any introduction of a newline through '\n' in this enforces the beginning of a further comment line. Comment lines will be added to the header immediately after the 'PGM / RUN BY / DATE' record. Default is an empty option field, meaning that no additional comment line will be added to the RINEX header.

If you specify a 'New' but no 'Old' marker/antenna/receiver name, the corresponding data field in the emerging new RINEX Observation file will be filled accordingly. If you in addition specify an 'Old' marker/antenna/receiver name, the corresponding data field in the emerging new RINEX Observation file will only be filled accordingly where 'Old' specifications match existing file content.

Figure 13: Example for BNC's 'RINEX Editing Options' window

Figure 14: Example for RINEX file concatenation with BNC

#### 2.6.8 Command Line, No Window - optional

BNC applies options from the configuration file but allows updating every one of them on the command line while the content of the configuration file remains unchanged, see section on 'Command Line Options'. Note the following syntax for Command Line Interface (CLI) options:

       --key <keyName> <keyValue>

Parameter <keyName> stands for the name of an option contained in the configuration file and <keyValue> stands for the value you want to assign to it. This functionality may be helpful in the 'RINEX Editing & QC' context when running BNC on a routine basis for maintaining a RINEX file archive.

You may use asterisk '*' and/or question mark '?' wildcard characters as shown with the following globbing command line option to specify a selection of files in the working directory:

       --key reqcObsFile "Input/BRUX00BEL_S_2021125*_15M_01S_MO.rnx"

or:

       --key reqcObsFile Input/BRUX00BEL_S_2021125\*_15M_01S_MO.rnx

The following example for a Linux platform calls BNC in 'no window' mode with a local configuration file 'rnx.conf' for concatenating four 15min RINEX files from station BRUX00BEL residing in the 'Input' directory to produce an hourly RINEX Version 3 file with 30 seconds sampling interval:

      /home/user/bnc --nw --conf rnx.conf \
           --key reqcAction Edit/Concatenate \
           --key reqcObsFile Input/BRUX00BEL_S_2021125\*_15M_01S_MO.rnx \
           --key reqcOutLogFile Output/RinexConcat.log \
           --key reqcRnxVersion 3 \
           --key reqcSampling 30 \
           --key reqcOutLogFile Output/RinexConcat.log \
           --key reqcOutObsFile Output/BRUX00BEL_S_20211251100_01H_01S_MO.rnx

The following Linux command line produces RINEX QC plots (see Estey and Meertens 1999) offline in 'no window' mode and saves them in directory '/home/user'. Introducing a dummy configuration file /dev/null makes sure that no configuration options previously saved on disc are used:

      /home/user/bnc --nw --conf /dev/null -display :1 --platform offscreen \
           --key reqcAction Analyze \
           --key reqcObsFile Input/MAO000USA_R_20221720000_01D_30S_MO.rnx \
           --key reqcNavFile Input/MAO000USA_R_20221720000_01D_MN.rnx \
           --key reqcSkyPlotSignals "G:1&2&5 R:1&2 E:1&5&7 C:2&6 J:1&2" \
           --key reqcOutLogFile Output/RinexQc.log \
           --key reqcPlotDir Output 2>/dev/null

The following Linux command line produces the same RINEX QC plots in interactive autoStart mode:

      /home/user/bnc --conf /dev/null \
           --key reqcAction Analyze \
           --key reqcObsFile Input/MAO000USA_R_20221720000_01D_30S_MO.rnx \
           --key reqcNavFile Input/MAO000USA_R_20221720000_01D_MN.rnx \
           --key reqcSkyPlotSignals "G:1&2&5 R:1&2 E:1&5&7 C:2&6 J:1&2" \
           --key reqcOutLogFile Output/RinexQc.log \
           --key startTab 4 --key autoStart 2

The following is a list of available key names for 'RINEX Editing & QC' (short: REQC, pronounced 'rek') options and their meaning, cf. section 'Configuration Examples':

Keyname |  | Meaning
reqcAction |  | RINEX Editing & QC action
reqcObsFile |  | RINEX Observation input file(s)
reqcNavFile |  | RINEX Navigation input files(s)
reqcOutObsFile |  | RINEX Observation output file
reqcOutNavFile |  | RINEX Navigation output file
reqcOutLogFile |  | Logfile
reqcLogSummaryOnly |  | Summary of Logfile
reqcSkyPlotSignals |  | Plots for signals
reqcPlotDir |  | RINEX QC plot directory
reqcRnxVersion |  | RINEX version of emerging new file
reqcSampling |  | Sampling interval of emerging new RINEX file
reqcV2Priority |  | Version 2 Signal Priority
reqcStartDateTime |  | Begin of emerging new RINEX file
reqcEndDateTime |  | End of emerging new RINEX file
reqcRunBy |  | Operator name
reqcUseObsTypes |  | GNSS systems and observation types
reqcComment |  | Additional comment lines
reqcOldMarkerName |  | Old marker name
reqcNewMarkerName |  | New marker name
reqcOldAntennaName |  | Old antenna name
reqcNewAntennaName |  | New antenna name
reqcOldAntennaNumber |  | Old antenna number
reqcNewAntennaNumber |  | New antenna number
reqcOldAntennadN |  | Old component of north eccentricity
reqcOldAntennadE |  | Old component of east eccentricity
reqcOldAntennadU |  | Old component of up eccentricity
reqcNewAntennadN |  | New component of north eccentricity
reqcNewAntennadE |  | New component of east eccentricity
reqcNewAntennadU |  | New component of up eccentricity
reqcOldReceiverName |  | Old receiver name
reqcNewReceiverName |  | New receiver name
reqcOldReceiverNumber |  | Old receiver number
reqcNewReceiverNumber |  | New receiver number

#### 2.7 SP3 Comparison

BNC allows to compare the contents of two files with GNSS orbit and clock data in SP3 format. SP3 ASCII files basically contain a list of records over a certain period of time. Each record carries a time tag, the XYZ position of the satellite's Center of Mass at that time and the corresponding satellite clock value. Both SP3 files may contain some records for different epochs. If so, then BNC only compares records for identical epochs. BNC accepts that a specific GNSS system or a specific satellite is only available from one of the SP3 files. Note that BNC does not interpolate orbits when comparing SP3 files.

To compare satellite clocks provided by the two files, BNC first converts coordinate differences dX,dY,dZ into along track, out-of-plane, and radial components. It then corrects the clock differences for the radial components of coordinate differences. RMS values of clock differences are finally calculated after introducing at first one offset 'per epoch for all satellites' and secondly one offset 'per satellite for all epochs'.

Figure 15: Example for comparing two SP3 files with satellite orbit and clock data using BNC

#### 2.7.1 Input SP3 Files - optional

Specify the full paths of two SP3 files, separate them by comma.

#### 2.7.2 Exclude Satellites - optional

You may want to exclude one or more satellites in your SP3 files from the comparison. Or you may like to exclude all satellites of a specific GNSS system from the comparison. The following are example strings to be entered for excluding satellites from the comparison.

- G05,G31 (excluding GPS satellites with PRN 5 and 31)
- G (excluding all GPS satellites)
- R (excluding all GLONASS satellites)
- R12,R24 (excluding GLONASS satellites with slot number 12 and 24)
- G04,G31,R (excluding GPS satellites with PRN 4 and 31 as well as all GLONASS satellites)

Default is an empty option field, meaning that no satellite will be excluded from the comparison.

#### 2.7.3 Logfile - mandatory if 'Input SP3 Files' is set

Specify a logfile name to save results of the SP3 file comparison. BNC provides an option 'Summary only' to limit logfile content to 'Summary' information only.

The following is an example for a SP3 Comparison logfile:

    ! SP3 File 1: /data/stuerze/tools/BNC/Example_Configs/Input/CNE1MGXRTS_20222410000_01D_05S_ORB.SP3
    ! SP3 File 2: /data/stuerze/tools/BNC/Example_Configs/Input/BKG1MGXRTS_20222410000_01D_05S_ORB.SP3
    !
    ! Clock residuals and orbit differences in [m]
    ! ----------------------------------------------------------------------------
    !
    !  Epoch                PRN  radial   along   out        clk    clkRed   iPRN
    ! ----------------------------------------------------------------------------
    2022-08-29_08:01:30.000 G01  0.0297 -0.0526 -0.0198    -0.0005 -0.0301     1
    2022-08-29_08:01:30.000 G02  0.0225 -0.0179  0.0055     0.0054 -0.0171     2
    2022-08-29_08:01:30.000 G03  0.0210 -0.0387 -0.0153     0.0025 -0.0185     3
    2022-08-29_08:01:30.000 G06  0.0650  0.0599 -0.0260    -0.0074 -0.0724     6
    2022-08-29_08:01:30.000 G07  0.0112  0.0774  0.0331    -0.0021 -0.0133     7
    2022-08-29_08:01:30.000 G08  0.0241  0.0725  0.0009    -0.0008 -0.0248     8
    2022-08-29_08:01:30.000 G09 -0.0145  0.0669  0.0069     0.0051  0.0196     9
    2022-08-29_08:01:30.000 G11  0.0375  0.0650 -0.0080    -0.0094 -0.0469    11
    2022-08-29_08:01:30.000 G12  0.0634  0.0229 -0.0003     0.0078 -0.0556    12
    2022-08-29_08:01:30.000 G13  0.0163  0.0551  0.0904     0.0010 -0.0153    13
    2022-08-29_08:01:30.000 G14  0.0365  0.0646 -0.0398     0.0034 -0.0332    14
    2022-08-29_08:01:30.000 G15  0.0175  0.0892  0.0512    -0.0032 -0.0207    15
    2022-08-29_08:01:30.000 G16  0.0453  0.0408  0.0346    -0.0029 -0.0483    16
    2022-08-29_08:01:30.000 G17  0.0381 -0.0064 -0.0701     0.0020 -0.0362    17
    2022-08-29_08:01:30.000 G18 -0.0886  0.0031  0.0721    -0.0055  0.0831    18
    2022-08-29_08:01:30.000 G19  0.0310 -0.0190 -0.0264    -0.0000 -0.0311    19
    2022-08-29_08:01:30.000 G20  0.0199  0.0308  0.0476     0.0106 -0.0093    20
    2022-08-29_08:01:30.000 G21  0.0163  0.0079 -0.0464     0.0047 -0.0116    21
    2022-08-29_08:01:30.000 G22  0.0471  0.0173 -0.0315    -0.0023 -0.0494    22
    2022-08-29_08:01:30.000 G23 -0.0354 -0.0042  0.0247    -0.0035  0.0319    23
    2022-08-29_08:01:30.000 G24  0.0110  0.0030 -0.0323     0.0112  0.0002    24
    2022-08-29_08:01:30.000 G25  0.0037  0.0712 -0.0175    -0.0019 -0.0056    25
    2022-08-29_08:01:30.000 G26  0.0421 -0.0002  0.0511    -0.0009 -0.0430    26
    2022-08-29_08:01:30.000 G27  0.0164  0.1203  0.0347    -0.0041 -0.0205    27
    2022-08-29_08:01:30.000 G29 -0.0093  0.0141  0.0570     0.0095  0.0188    29
    2022-08-29_08:01:30.000 G30  0.0199  0.0805  0.0529    -0.0074 -0.0273    30
    2022-08-29_08:01:30.000 G31  0.0336 -0.0079 -0.0281    -0.0132 -0.0468    31
    2022-08-29_08:01:30.000 G32 -0.0185 -0.0200 -0.0103     0.0019  0.0205    32
    ..
    !
    ! Summary
    ! -----------------------------------------------------------------------------------------------------------------
    !
    !     PRN   radialRMS   alongRMS    outRMS     3DRMS      nOrb    clkRMS    clkRedRMS   clkRedSig   nClk    Offset
    !              [mm]       [mm]        [mm]      [mm]      [-]      [ns]        [ns]        [ns]      [-]     [ns]
    ! -----------------------------------------------------------------------------------------------------------------
    ..
    !     G01       49.4       90.1        4.0      102.8     165       0.01       0.16       0.16       165     -2.71
    !     G02       39.8       34.2        6.2       52.8     165       0.01       0.13       0.13       165      4.13
    !     G03       27.8       57.7       12.8       65.3     165       0.01       0.09       0.09       165     -2.18
    !     G06       61.8       50.7       22.2       82.9     165       0.01       0.21       0.21       165     -2.70
    !     G07       22.2       80.3       31.7       89.2     165       0.01       0.07       0.07       165     -1.26
    !     G08       18.8      102.1       12.7      104.6     165       0.01       0.06       0.06       165      1.17
    !     G09        9.8       87.2        5.6       87.9     165       0.01       0.03       0.03       165      0.21
    !     G11       54.8       65.5        6.9       85.6     165       0.03       0.18       0.18       165     -1.93
    !     G12       64.4       48.2        7.3       80.8     165       0.02       0.21       0.21       165     -1.45
    !     G13       17.1       45.9       88.8      101.4     165       0.01       0.06       0.06       165     -0.67
    !     G14       34.9       79.4       32.6       92.7     165       0.01       0.12       0.12       165     -2.07
    !     G15       33.4       38.1       45.0       67.8     165       0.01       0.11       0.11       165     -2.19
    !     G16       50.0       67.9       51.2       98.7     165       0.01       0.17       0.17       165      3.27
    !     G17       44.1       12.0       73.8       86.8     165       0.01       0.15       0.15       165     -1.67
    !     G18       78.7       15.0       65.4      103.4     165       0.01       0.26       0.26       165     -2.37
    !     G19       29.1       12.7       38.2       49.7     165       0.01       0.10       0.10       165      6.27
    !     G20       19.0       25.2       33.4       45.9     165       0.02       0.06       0.06       165      5.58
    !     G21        8.6       13.3       44.5       47.3     165       0.01       0.03       0.03       165      5.40
    !     G22       53.5       18.3       29.0       63.5     165       0.01       0.18       0.18       165      1.54
    !     G23       29.8       35.8       16.1       49.2     165       0.01       0.10       0.10       165     -1.84
    !     G24       13.4       20.2       28.4       37.3     165       0.02       0.04       0.04       165     -2.67
    !     G25        9.2       88.4       28.0       93.2     165       0.02       0.04       0.04       165      1.68
    !     G26       45.2       33.4       60.5       82.5     165       0.02       0.15       0.15       165      0.36
    !     G27       22.4      128.4       39.9      136.3     165       0.01       0.07       0.07       165      0.59
    !     G29       17.2       42.3       59.7       75.1     165       0.02       0.06       0.06       165     -2.56
    !     G30       19.9       91.7       61.2      112.0     165       0.01       0.07       0.07       165      2.15
    !     G31       30.3       20.1       39.4       53.6     165       0.04       0.11       0.11       165     -1.97
    !     G32       16.7       28.9        8.2       34.4     165       0.01       0.06       0.06       165     -2.11
    !
    !   Total       55.2       87.7       69.0      124.5   10395       0.02       0.18       0.18     10395

The first part of this output following string 'following string' uses the following abbreviations:

'Epoch' | Epoch Date and Time
'PRN' | Satellite specification
'radial' | Radial component of orbit coordinate difference [m]
'along' | Along track component of orbit coordinate difference [m]
'out' | Out-of-plane component of orbit coordinate difference [m]
'clk' | Clock difference [m]
'clkRed' | Clock difference reduced by radial component of orbit coordinate difference [m]
'iPRN' | BNC internal sequence number

The second part following string 'Summary' provides a summary of the comparison using the following abbreviations:
! PRN radialRMS alongRMS outRMS 3DRMS nOrb clkRMS clkRedRMS clkRedSig nClk Offset ! [mm] [mm] [mm] [mm] [-] [ns] [ns] [ns] [-] [ns]

'PRN' | Satellite specification
'radialRMS' | RMS of the radial component of orbit coordinate differences [mm]
'alongRMS' | RMS of the along track component of orbit coordinate differences [mm]
'outRMS' | RMS of the out-of-plane component of orbit coordinate differences [mm]
'3DRMS' | 3D RMS of the orbit coordinate differences [mm]
'nOrb' | Number of epochs used in in orbit comparison
'clkRMS' | RMS of clock differences [ns]
'clkRedRMS' | RMS of The clock differences after reduction of radial orbit differences [ns]
'clkRedSig' | Sigma of the clock differences after reduction of radial orbit differences [ns]
'nClk' | Number of epochs use in clock comparisons
'Offset' | Clock offset [ns]

Figure 16: Graphical results from an example comparison of two SP3 files with satellite orbit and clock data using BNC

#### 2.8 Broadcast Corrections

Differential GNSS and RTK operation using RTCM streams is currently based on corrections and/or raw measurements from single or multiple reference stations. This approach to differential positioning uses 'observation space' information. The representation with the RTCM standard can be called 'Observation Space Representation' (OSR).

An alternative to the observation space approach is the so-called 'state space' approach. The principle here is to provide information on individual error sources. It can be called 'State Space Representation' (SSR). For a rover position, state space information concerning precise satellite clocks, orbits, ionosphere, troposphere et cetera can be converted into observation space and used to correct the rover observables for more accurate positioning. Alternatively, the state information can be used directly in the rover's processing or adjustment model.

RTCM is currently developing Version 3 messages to transport SSR corrections in real-time. They may refer to satellite Antenna Phase Center (APC) or Center of Mass (CoM). Because the development was stagnating in RTCM over years, IGS has developed similar SSR messages in parallel. Available and unter development are:

- SSR, Step I:

- Orbit corrections to Broadcast Ephemeris
- Clock corrections to Broadcast Ephemeris
- High-rate clock corrections to Broadcast Ephemeris
- Combined orbit and clock corrections to Broadcast Ephemeris
- User Range Accuracy (URA)
- High Rate User Range Accuracy (HR URA)
- Code biases

- SSR, Step II (will change in 2023):

- Phase biases
- Vertical Total Electron Content (VTEC)

SSR streams carrying these messages may be used e.g. to support real-time Precise Point Positioning (PPP) applications.

Orbit corrections are provided in along-track, out-of-plane and radial components. These components are defined in the Earth-Centered, Earth-Fixed reference frame of the Broadcast Ephemeris. For an observer in this frame, the along-track component is aligned in both direction and sign with the velocity vector, the out-of-plane component is perpendicular to the plane defined by the satellite position and velocity vectors, and the radial direction is perpendicular to the along track and out-of-plane ones. The three components form a right-handed orthogonal system.

After applying corrections, the satellite position and clock is referred to the 'ionospheric free' phase center of the antenna which is compatible with the broadcast orbit reference.

The orbit and clock corrections do not include local effects like Ocean Loading, Solid Earth Tides or tropospheric delays. However, accurate single frequency applications can be corrected for global ionospheric effects using so-call VTEC messages for global ionospheric state parameters.

While we have a plain ASCII standard for saving Broadcast Ephemeris in RINEX Navigation files, we do not have an equivalent standard for corrections to Broadcast Ephemeris. Hence, BNC saves Broadcast Correction files following its own format definition.

The filename convention for Broadcast Correction files follows in general the convention for RINEX Version 3/4 files except for the two characters of the data type as well as for the characters of the filename suffix, which is set to 'ssr': The files below contains one day's data. 'MC' stands for 'Multi Constellation Clock' data and 'ION' stands for 'Ionosphere' data.

    SSRA00CNE1_S_20222750000_01D_MC.ssr
    IONO00IGS1_S_20222740000_01D_ION.ssr

BNC's Broadcast Correction files contain blocks of records in plain ASCII format. Each block covers information about one specific topic and starts with an 'Epoch Record'.

The 'Epoch Record' of a Broadcast Correction block

The leading 'Epoch Record' of each block in a Broadcast Correction file contains 11 parameters. Example:

    > ORBIT 2022 10 01 23 59 45.0 2 110 SSRA00CNE1

Their meaning is as follows:

1. Special character '>' is the first character in each 'Epoch Record' (as we have it in RINEX Version 3)
2. SSR message or topic descriptor, valid descriptors are:
   ORBIT, CLOCK, CODE_BIAS, PHASE_BIAS, or VTEC
3. Year, GPS time
4. Month, GPS time
5. Day, GPS time
6. Hour, GPS time
7. Minute, GPS time
8. Second, GPS time
9. SSR message update interval indicator

- 0 = 1 sec
- 1 = 2 sec
- 2 = 5 sec
- 3 = 10 sec
- 4 = 15 sec
- 5 = 30 sec
- 6 = 60 sec
- 7 = 120 sec
- 8 = 240 sec
- 9 = 300 sec
- 10 = 600 sec
- 11 = 900 sec
- 12 = 1800 sec
- 13 = 3600 sec
- 14 = 7200 sec
- 15 = 10800 sec

10. Number of following records in this block
11. Mountpoint, source/stream indicator

Each of the following 'satellite records' in such a block carries information for one specific satellite. Undefined parameters in the 'satellite records' could be set to zero "0.000".

Example for block 'ORBIT' carrying orbit corrections

    > ORBIT 2022 10 01 23 59 45.0 2 110 SSRA00CNE1
    G01          93    -0.1588    -0.8664    -0.0600        0.2210    -0.1200    -0.0400
    G02          33     0.0491    -1.7468     0.5608        0.1820     0.0040     0.0200
    G03          72    -0.1495    -0.5408     0.2372        0.1190    -0.1640     0.1200
    G04         183     0.1435    -0.1232     0.5380        0.0090    -0.1400     0.1080
    G06          94    -0.2037    -2.1956    -0.1688        0.2540    -0.1280     0.0480
    ..
    R01          11    -0.7444     2.7684    -2.6576       -1.7740    -0.0480    -1.6440
    R02          11    -0.0127     0.9224    -0.5828       -0.0830     0.4400    -0.2480
    R03          11     1.1832     0.5412     1.0988        0.6670     0.8160     0.7280
    R04          11     0.3613    -1.5672     1.3608        0.1840    -0.4520     0.9440
    ..
    E01         110    -0.0509    -0.1328    -0.1212        0.0010    -0.0960     0.0000
    E02         110    -0.1341    -0.3820     0.3552       -0.0040    -0.1200     0.0120
    E03         110     0.0744    -0.2620    -0.3392        0.0160    -0.1280    -0.0120
    E04         110    -0.0925     0.1708    -0.0212        0.0200    -0.0520     0.0120
    ..
    C01         115     2.3749     0.8224    -3.0080        0.0360    -0.0440    -0.0320
    C02         115     4.4831     0.7836    -3.3052        0.0070    -0.0120     0.4240

Records in this block provide the following satellite specific information:

- GNSS Indicator and Satellite Vehicle Pseudo Random Number
- IOD referring to Broadcast Ephemeris set
- Radial Component of Orbit Correction to Broadcast Ephemeris [m]
- Along-track Component of Orbit Correction to Broadcast Ephemeris [m]
- Out-of-plane Component of Orbit Correction to Broadcast Ephemeris [m]
- Velocity of Radial Component of Orbit Correction to Broadcast Ephemeris [mm/s]
- Velocity of Along-track Component of Orbit Correction to Broadcast Ephemeris [mm/s]
- Velocity of Out-of-plane Component of Orbit Correction to Broadcast Ephemeris [mm/s]

Example for block 'CLOCK' carrying clock corrections

    > CLOCK 2022 10 01 23 59 45.0 2 110 SSRA00CNE1
    G01          93     0.1498     0.0000     0.0000
    G02          33    -0.3686     0.0000     0.0000
    G03          72     0.2208     0.0000     0.0000
    G04         183    -0.9087     0.0000     0.0000
    ..
    R01          11     3.2911     0.0000     0.0000
    R02          11     2.7534     0.0000     0.0000
    R03          11    -3.0149     0.0000     0.0000
    R04          11    -4.2644     0.0000     0.0000
    ..
    E01         110    -0.1014     0.0000     0.0000
    E02         110     0.3910     0.0000     0.0000
    E03         110    -0.2841     0.0000     0.0000
    E04         110     0.0697     0.0000     0.0000
    ..
    C01         115     0.0000     0.0000     0.0000
    C02         115    -7.1950     0.0000     0.0000

Records in this block provide the following satellite specific information:

- GNSS Indicator and Satellite Vehicle Pseudo Random Number
- IOD referring to Broadcast Ephemeris set
- C0 polynomial coefficient for Clock Correction to Broadcast Ephemeris [m]
- C1 polynomial coefficient for Clock Correction to Broadcast Ephemeris [mm/s]
- C2 polynomial coefficient for Clock Correction to Broadcast Ephemeris [mm/s**2]

Example for block 'CODE_BIAS' carrying code biases

    > CODE_BIAS 2022 10 01 23 59 45.0 2 110 SSRA00CNE1
    G01    7   1C    -2.6900   1P    -2.8300   1W    -3.1000   2L    -3.8000   2S    -3.8000   2W    -5.1000   5Q    -0.6300
    G02    4   1C     3.1700   1P     3.1400   1W     3.6600   2W     6.0300
    G03    7   1C    -2.0500   1P    -1.8800   1W    -2.2600   2L    -3.0300   2S    -2.9800   2W    -3.7200   5Q    -0.6400
    G04    7   1C     0.6300   1P     0.7000   1W     0.4800   2L     1.9200   2S     1.9100   2W     0.8000   5Q     0.5200
    ..
    R01    4   1C    -2.6700   1P    -2.5800   2C    -3.6100   2P    -4.2500
    R02    4   1C    -0.2300   1P    -0.2700   2C    -0.4400   2P    -0.4400
    R03    4   1C     1.3200   1P     1.2700   2C     2.0100   2P     2.0900
    R04    4   1C     1.7100   1P     1.5700   2C     2.5700   2P     2.5800
    ..
    E01    4   1C    -0.1500   5Q    -0.2700   6C    -1.0300   7Q    -0.2300
    E02    4   1C     0.3000   5Q     0.5300   6C    -0.3000   7Q     0.6800
    E03    4   1C    -0.9000   5Q    -1.6100   6C    -0.6600   7Q    -1.5700
    E04    4   1C     0.9400   5Q     1.6900   6C     0.9500   7Q     1.6500
    ..
    C01    3   2I     0.5900   6I     0.8900   7I    -5.2500
    C02    3   2I     4.4700   6I     6.7600   7I     1.9700

Records in this block provide the following satellite specific information:

- GNSS Indicator and Satellite Vehicle Pseudo Random Number
- Number of Code Biases, succeeded by code specific information:

- Indicator to specify the signal and tracking mode
- Code Bias [m]
- Indicator to specify the signal and tracking mode
- Code Bias [m]
- etc.

Example for block 'PHASE_BIAS' carrying phase biases

    > PHASE_BIAS 2022 10 01 23 59 45.0 2 110 SSRA00CNE1
     0   1
    G01 157.50000000   0.00000000    3   1C    -0.6023   1   2   7   2W    -0.8679   1   2   7   5I    -0.8614   1   2   7
    G02  13.35937500   0.00000000    2   1C     0.7878   1   2   4   2W     1.1236   1   2   4
    G03 114.60937500   0.00000000    3   1C     0.5267   1   2   5   2W     0.6362   1   2   5   5I     0.5909   1   2   5
    G04 142.73437500   0.00000000    3   1C    -0.2596   1   2   4   2W    -0.3408   1   2   4   5I    -0.3128   1   2   4
    ..
    R01  61.87500000   0.00000000    0
    R02  63.28125000   0.00000000    0
    R03  81.56250000   0.00000000    0
    R04 104.76562500   0.00000000    0
    ..
    E01 311.48437500   0.00000000    4   1C    -0.3417   1   2   7   5Q    -0.4521   1   2   7   7Q    -3.1509   1   2   7   6C    -3.4182   1   2   7
    E02 228.51562500   0.00000000    4   1C    -0.2393   1   2   5   5Q    -0.5462   1   2   5   7Q    -2.9695   1   2   5   6C    -3.3839   1   2   5
    E03 137.10937500   0.00000000    4   1C    -0.1708   1   2   4   5Q    -0.1185   1   2   4   7Q    -2.6085   1   2   4   6C    -3.0863   1   2   4
    E04  42.89062500   0.00000000    4   1C     0.5145   1   2  11   5Q     0.6448   1   2  11   7Q    -2.0412   1   2  11   6C    -2.5102   1   2  11
    ..
    C01   0.00000000   0.00000000    3   2I    -0.2411   0   2   6   7I     2.9125   0   2   6   6I    -0.3651   0   2   6
    C02   0.00000000   0.00000000    3   2I     0.5378   0   2  15   7I     4.1515   0   2  15   6I     0.7121   0   2  15

The second record in this block provides the following consistency information:

- Dispersive bias consistency indicatory
  0 − phase biases valid for non-dispersive signal only
  1 − phase biases maintain consistency between non-dispersive and all original dispersive phase signals
- MW consistency indicator
  0 − code and phase biases are independently derived
  1 − consistency between code and phase biases is maintained for the MW combinations

Following records provide satellite specific information:

- GNSS Indicator and Satellite Vehicle Pseudo Random Number
- Yaw angle [°], restricted to [0°... 360°]
- Yaw rate [°/s]
- Number of phase biases in this record, succeeded by phase specific information:

- Signal and tracking mode indicator
- Phase bias [m]
- Signal integer indicator
- Signal wide-lane integer indicator
- Signal discontinuity counter

Example for block 'VTEC' carrying ionospheric corrections

     VTEC 2022 10 02 00 00 00.0 6 1 SSRA00CNE1
     1 12 12   450000.0
       22.6900     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.2000    11.6050     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
       -8.7500    -0.0200     2.0250     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
       -0.2900    -1.5900     0.3700    -0.1750     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        3.1850    -0.1150    -0.2350     0.0050     0.0300     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
       -0.1050     1.3550    -0.4000    -0.3400    -0.0150    -0.2550     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
       -1.1200     0.0800     0.1100    -0.1350     0.0650    -0.0050     0.0400     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.1600    -0.3650     0.4200     0.0750    -0.0400    -0.0350     0.0950     0.3000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.6950    -0.0750     0.0500     0.0450    -0.0800     0.0600    -0.0500     0.0200    -0.0100     0.0000     0.0000     0.0000     0.0000
        0.0200     0.0150    -0.0800    -0.0500     0.0600     0.0200    -0.0900    -0.1000     0.0400    -0.1050     0.0000     0.0000     0.0000
       -0.2600    -0.2800    -0.0550    -0.0100     0.1200    -0.0150    -0.0200    -0.0050    -0.0250    -0.0750     0.0200     0.0000     0.0000
        0.1850    -0.0400     0.1250     0.0100     0.0000    -0.0250     0.0600     0.0700     0.0000     0.0050    -0.0250    -0.0050     0.0000
       -0.0500    -0.0200     0.0850     0.0700    -0.0850     0.0350    -0.0350     0.0350    -0.0250     0.0200     0.0200     0.0300     0.0250
        0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000     1.5350     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000     0.1150    -1.3850     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000    -2.0150     0.2500     0.9750     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000     0.0450     0.3200     0.1500     0.2200     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000     1.0400    -0.0950    -0.0600     0.1100    -0.2750     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000    -0.1150    -0.5000    -0.0650    -0.1800    -0.0300     0.0100     0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000    -0.5200    -0.0100    -0.0150    -0.0300    -0.1350     0.0100     0.0050     0.0000     0.0000     0.0000     0.0000     0.0000
        0.0000     0.0900     0.1400     0.0550     0.0450     0.0300     0.1300     0.0250     0.0650     0.0000     0.0000     0.0000     0.0000
        0.0000     0.0800     0.0350     0.0600     0.0150    -0.0700    -0.0100    -0.0100     0.0100     0.1000     0.0000     0.0000     0.0000
        0.0000    -0.1550    -0.1400     0.0250    -0.0100    -0.0450    -0.0250     0.0200    -0.0800     0.0150    -0.1000     0.0000     0.0000
        0.0000     0.0550    -0.0100    -0.0300     0.0050     0.1250    -0.0450    -0.0150    -0.0100     0.0250    -0.0200    -0.0600     0.0000
        0.0000     0.0750    -0.1400     0.0850    -0.0200    -0.0150     0.0750     0.0000     0.0050     0.0200     0.0250     0.0100     0.0450

The second record in this block provides four parameters:

- Layer number
- Maximum degree of spherical harmonics
- Maximum order of spherical harmonics
- Height of ionospheric layer [m]

Subsequent records in this block provide the following information:

- Spherical harmonic coefficients C and S, sorted by degree and order (0 to maximum)

#### 2.8.1 Directory, ASCII - optional

Specify a directory for saving Broadcast Corrections in files. If the specified directory does not exist, BNC will not create Broadcast Correction files. Default value for Broadcast Correction 'Directory' is an empty option field, meaning that no Broadcast Correction files will be created.

#### 2.8.2 Interval - mandatory if 'Directory, ASCII' is set

Select the length of the Broadcast Correction files. The default value is '1 day'.

#### 2.8.3 Port - optional

BNC can output epoch by epoch synchronized Broadcast Corrections in ASCII format on your local host (IP 127.0.0.1) through an IP 'Port'. Specify an IP port number to activate this function. The default is an empty option field, meaning that no Broadcast Correction output via IP port is generated.

The output format is the same to the format used for saving Broadcast Corrections in a file.

The source code for BNC comes with an example Perl script 'test_tcpip_client.pl' that allows to read BNC's Broadcast Corrections from the IP port for verification.

Figure 17: Example for pulling, saving and output of Broadcast Corrections using BNC

#### 2.9 Feed Engine

BNC can produce synchronized or unsynchronized observations epoch by epoch from all stations and satellites to feed a real-time GNSS network engine. Observations can be streamed out through an IP port and/or saved in a local file. The output is always in the same plain ASCII format and sorted per incoming stream.

Each epoch in the synchronized output begins with a line containing the GPS Week Number and the seconds within the GPS Week. Following lines begin with the mountpoint string of the stream which provides the observations followed by a satellite number. Specifications for satellite number, code, phase, doppler and signal strength data follow definitions presented in the RINEX Version 3 documentation. In case of phase observations, a 'Slip Counter' is added. The end of an epoch is indicated by an empty line.

A valid 'Slip Counter' is only presented for observations from RTCM Version 2 streams (Cummulative Loss of Lock Indicator). In RTCM Version 3 streams a 'Lock Time Indicator' is available instead. This parameter indicates a measure of the amount of time that has elapsed during which the receiver has maintained continuous lock on that satellite signal. If a cycle slip occurs during the previous measurement cycle, the 'Lock Time Indicator' will be reset to zero. But, this 'Lock Time Indicator' ist defined with different resolution for different RTCM version 3 observation types (MSMi, legacy messages).

From the RTCM version 3 'Lock Time Indicator' a valid 'Lock Time' can be computed with the respective calculation rule. This parameter provides a measure of the amount of time that has elapsed during which the receiver has maintained continuous lock on that satellite signal in seconds. If a cycle slip occurs during the previous measurement cycle, the 'Lock Time' will decrease. This information will be used, to provide a 'Slip Counter' for RTCM Version 3 observations as well. With it, we have an output format that is independent from the RTCM version of the observations. The 'Lock Time' output can be activated optional.

The following table describes the format of BNC's synchronized output of GNSS observations which consists of 'Epoch Records' and 'Observation Records'. Each Epoch Record is followed by one or more Observation Records. The Observation Record is repeated for each satellite having been observed in the current epoch. The length of an Observation Record is given by the number of observation types for this satellite.

Table 2: Contents and format of synchronized output of observations feeding a GNSS engine

| Example | Format
Epoch Record |  |
Record Identifier | > | A1
GPS Week Number | 1850 | 1X,I4
GPS Seconds of Week | 120556.0000000 | 1X,F14.7
Observation Record |  |
Mountpoint | WTZR00DEU0 | A
Satellite Number | G01 | 1X,A3
Pseudo-Range Data |  |
Observation Code | C1C | 1X,A3
Pseudo-Range Observation | 25394034.112 | 1X,F14.3
Carrier Phase Data |  |
Observation Code | L1C | 1X,A3
Carrier Phase Observation | 133446552.870 | 1X,F14.3
Slip Counter | 11 | 1X,I4
Doppler Data |  |
Observation Code | D1C | 1X,A3
Doppler Observation | -87.977 | 1X,F14.3
Signal Strength |  |
Observation Code | S2W | 1X,A3
Observed Signal Strength | 34.750 | 1X,F8.3
Lock Time (optional) |  |
Observation Code | T2W | 1X,A3
Computed Lock Time | 937.000 | 1X,F8.3

The following is an example epoch for synchronized file and IP port output, which presents observations from GPS, GLONASS, Galileo, BDS (BeiDou), and QZSS satellites as collected through the stream CUT000AUS0:

    > 2235 161041.0000000
    CUT000AUS0 G05 C1C   22397546.124 L1C  117700392.329    0 D1C      -1640.054 S1C   43.812 C2W   22397552.729 L2W   91714594.476    0 S2W   40.500 C2X   22397553.316 L2X   91714226.480    0 S2X   42.312
    CUT000AUS0 G07 C1C   25034166.757 L1C  131554935.204    0 D1C      -2648.320 S1C   35.875 C2W   25034175.115 L2W  102510355.979    0 S2W   16.312 C2X   25034174.119 L2X  102511007.981    0 S2X   33.188
    CUT000AUS0 G13 C1C   20632879.971 L1C  108426200.511    0 D1C       1654.761 S1C   49.188 C2W   20632886.032 L2W   84487953.991    0 S2W   39.625
    CUT000AUS0 G14 C1C   20965039.130 L1C  110171908.246    0 D1C      -1943.579 S1C   47.125 C2W   20965046.213 L2W   85848259.985    0 S2W   38.312 C2X   20965046.165 L2X   85847926.992    0 S2X   49.688 C5X   20965051.615 L5X   82271015.564    0 S5X   53.375
    CUT000AUS0 G15 C1C   22787067.176 L1C  119746749.144    0 D1C       2849.917 S1C   44.125 C2W   22787072.695 L2W   93309160.157    0 S2W   41.688 C2X   22787072.244 L2X   93309423.169    0 S2X   41.375
    CUT000AUS0 G17 C1C   22121616.350 L1C  116249765.638    0 D1C       2427.573 S1C   45.875 C2W   22121622.093 L2W   90584239.708    0 S2W   43.000 C2X   22121621.190 L2X   90584535.701    0 S2X   41.812
    CUT000AUS0 G19 C1C   23142771.219 L1C  121616393.429    0 D1C       3092.017 S1C   40.000 C2W   23142777.011 L2W   94766026.444    0 S2W   25.500
    CUT000AUS0 G20 C1C   23782796.965 L1C  124978693.104    0 D1C      -2903.804 S1C   37.188 C2W   23782803.282 L2W   97386261.663    0 S2W   19.312
    CUT000AUS0 G24 C1C   25377344.828 L1C  133359519.706    0 D1C       2260.874 S1C   32.625 C2W   25377355.059 L2W  103916508.791    0 S2W   23.188 C2X   25377354.491 L2X  103915493.811    0 S2X   36.125 C5X   25377356.208 L5X   99585948.817    0 S5X   39.375
    CUT000AUS0 G30 C1C   22338975.386 L1C  117392908.228    0 D1C      -1822.832 S1C   44.688 C2W   22338984.492 L2W   91475025.743    0 S2W   33.125 C2X   22338984.476 L2X   91474721.733    0 S2X   45.375 C5X   22338985.207 L5X   87662740.132    0 S5X   48.812
    CUT000AUS0 R04 C1C   23881837.357 L1C  127885658.422    0 D1C      -4453.798 S1C   40.812 C1P   23881835.733 L1P  127885658.404    0 S1P   38.625 C2C   23881844.628 L2C   99466667.235    0 S2C   38.375 C2P   23881844.445 L2P   99467375.252    0 S2P   36.688
    CUT000AUS0 R05 C1C   19993055.353 L1C  106874582.378    0 D1C      -2706.814 S1C   53.500 C1P   19993054.520 L1P  106874858.394    0 S1P   52.125 C2C   19993059.406 L2C   83123912.722    0 S2C   48.188 C2P   19993059.047 L2P   83124682.719    0 S2P   47.875
    CUT000AUS0 R06 C1C   20263132.945 L1C  108127358.039    0 D1C       2084.428 S1C   43.312 C1P   20263130.042 L1P  108128324.023    0 S1P   41.812
    CUT000AUS0 R07 C1C   24129676.299 L1C  129167523.333    0 D1C       4208.592 S1C   40.625 C1P   24129674.854 L1P  129168613.333    0 S1P   39.625 C2C   24129680.090 L2C  100463556.008    0 S2C   34.812 C2P   24129680.907 L2P  100463507.006    0 S2P   34.375
    CUT000AUS0 R09 C1C   22647210.193 L1C  120935222.748    0 D1C       2451.996 S1C   44.312 C1P   22647208.752 L1P  120934301.732    0 S1P   42.625 C2C   22647213.052 L2C   94060688.797    0 S2C   40.875 C2P   22647212.494 L2P   94060910.813    0 S2P   39.625
    CUT000AUS0 R15 C1C   21378136.341 L1C  114238110.662    0 D1C      -2695.283 S1C   50.875 C1P   21378136.614 L1P  114238720.680    0 S1P   49.188 C2C   21378140.999 L2C   88852381.654    0 S2C   46.000 C2P   21378141.210 L2P   88852004.661    0 S2P   45.125
    CUT000AUS0 R17 C1C   23445042.586 L1C  125459843.828    0 D1C       2139.073 S1C   42.188 C1P   23445040.392 L1P  125458606.837    0 S1P   40.625 C2C   23445044.755 L2C   97579282.106    0 S2C   38.375 C2P   23445045.002 L2P   97579658.104    0 S2P   37.312
    CUT000AUS0 R18 C1C   24487212.824 L1C  130713967.425    0 D1C       3289.885 S1C   38.688 C1P   24487211.697 L1P  130714476.414    0 S1P   37.312 C2C   24487222.117 L2C  101666522.038    0 S2C   36.625 C2P   24487222.877 L2P  101667012.053    0 S2P   37.000
    CUT000AUS0 R24 C1C   24406995.868 L1C  130515122.174    0 D1C       -363.589 S1C   37.625 C1P   24406994.508 L1P  130514566.195    0 S1P   36.500 C2C   24407001.743 L2C  101511238.922    0 S2C   35.375 C2P   24407001.646 L2P  101511808.907    0 S2P   33.875
    CUT000AUS0 E07 C1X   24981018.132 L1X  131275662.874    0 D1X      -2005.073 S1X   47.312 C7X   24981022.166 L7X  100587870.838    0 S7X   48.500 C8X   24981023.032 L8X   99309728.272    0 S8X   50.375 C5X   24981024.925 L5X   98030555.501    0 S5X   48.312
    CUT000AUS0 E19 C1X   26936516.560 L1X  141552478.497    0 D1X       2328.999 S1X   40.688 C7X   26936519.247 L7X  108462290.707    0 S7X   41.875 C8X   26936519.723 L8X  107083533.258    0 S8X   44.375 C5X   26936521.948 L5X  105704775.587    0 S5X   41.375
    CUT000AUS0 E21 C1X   24762234.566 L1X  130126590.523    0 D1X       1574.204 S1X   49.500 C7X   24762237.934 L7X   99707410.202    0 S7X   48.812 C8X   24762238.719 L8X   98439944.211    0 S8X   50.500 C5X   24762240.762 L5X   97172479.002    0 S5X   48.000
    CUT000AUS0 E27 C1X   23576704.592 L1X  123895989.025    0 D1X       -851.299 S1X   52.625 C7X   23576706.467 L7X   94933319.817    0 S7X   51.375 C8X   23576707.753 L8X   93726498.714    0 S8X   53.375 C5X   23576709.755 L5X   92519764.395    0 S5X   51.812
    CUT000AUS0 E30 C1X   27140817.882 L1X  142626806.094    0 D1X      -2516.660 S1X   41.812 C7X   27140820.356 L7X  109284744.583    0 S7X   42.125 C8X   27140821.870 L8X  107896108.822    0 S8X   45.312 C5X   27140823.870 L5X  106506823.863    0 S5X   42.688
    CUT000AUS0 J02 C1C   33315686.894 L1C  175075542.860    0 D1C        843.828 S1C   49.125 C2X   33315691.154 L2X  136421853.584    0 S2X   52.312 C5X   33315695.902 L5X  130737887.374    0 S5X   54.688
    CUT000AUS0 J03 C1C   42286566.136 L1C  222216744.902    0 D1C       1795.498 S1C   36.500 C2X   42286572.066 L2X  173156649.003    0 S2X   38.312 C5X   42286579.133 L5X  165941790.603    0 S5X   42.188
    CUT000AUS0 J07 C1C   37020705.829 L1C  194545830.880    0 D1C          3.584 S1C   39.625 C2X   37020708.694 L2X  151593502.133    0 S2X   47.812 C5X   37020714.323 L5X  145277106.855    0 S5X   51.500
    CUT000AUS0 C01 C2I   37452945.154 L2I  195027050.043    0 D2I         -4.219 S2I   41.875 C6I   37452936.772 L6I  158475266.419    0 S6I   42.875 C7I   37452941.707 L7I  150807351.407    0 S7I   42.625
    CUT000AUS0 C02 C2I   37629590.702 L2I  195946381.957    0 D2I        -65.684 S2I   37.625 C6I   37629580.568 L6I  159222468.315    0 S6I   41.688 C7I   37629584.237 L7I  151518158.493    0 S7I   42.500
    CUT000AUS0 C03 C2I   37043583.946 L2I  192895689.591    0 D2I        -42.959 S2I   42.000 C6I   37043573.338 L6I  156743260.534    0 S6I   45.000 C7I   37043578.637 L7I  149159229.293    0 S7I   44.500
    CUT000AUS0 C04 C2I   38728082.770 L2I  201667622.637    0 D2I         16.230 S2I   36.812 C6I   38728071.971 L6I  163871475.478    0 S6I   40.312 C7I   38728076.953 L7I  155942209.993    0 S7I   39.375
    CUT000AUS0 C05 C2I   39585341.980 L2I  206131634.311    0 D2I        -45.948 S2I   34.812 C6I   39585332.316 L6I  167498725.372    0 S6I   36.375 C7I   39585337.333 L7I  159393949.120    0 S7I   37.125
    CUT000AUS0 C06 C2I   36205815.127 L2I  188533341.895    0 D2I        293.803 S2I   47.625 C6I   36205801.585 L6I  153198815.977    0 S6I   47.000 C7I   36205808.771 L7I  145785979.158    0 S7I   46.812
    CUT000AUS0 C07 C2I   36955824.337 L2I  192438747.274    0 D2I       1083.432 S2I   43.688 C6I   36955809.966 L6I  156372256.627    0 S6I   44.625 C7I   36955818.699 L7I  148805860.823    0 S7I   45.500
    CUT000AUS0 C09 C2I   36538611.526 L2I  190266647.981    0 D2I        320.453 S2I   46.312 C6I   36538598.798 L6I  154607263.246    0 S6I   46.000 C7I   36538607.103 L7I  147126274.839    0 S7I   45.500
    CUT000AUS0 C10 C2I   37839575.262 L2I  197041085.539    0 D2I       1304.384 S2I   41.688 C6I   37839563.189 L6I  160112029.382    0 S6I   41.500 C7I   37839572.127 L7I  152364675.110    0 S7I   41.875
    CUT000AUS0 C11 C2I   26805755.942 L2I  139584609.535    0 D2I       -416.109 S2I   32.312 C6I   26805745.652 L6I  113423929.526    0 S6I   35.312 C7I   26805755.187 L7I  107935674.616    0 S7I   36.125
    CUT000AUS0 C13 C2I   41051458.729 L2I  213765992.637    0 D2I      -1850.508 S2I   34.000 C6I   41051455.342 L6I  173702372.800    0 S6I   32.875 C7I   41051464.924 L7I  165297417.662    0 S7I   34.000
    CUT000AUS0 C16 C2I   36059609.070 L2I  187772602.648    0 D2I        211.928 S2I   48.625 C6I   36059599.120 L6I  152579828.103    0 S6I   45.812 C7I   36059607.906 L7I  145196944.884    0 S7I   45.688
    CUT000AUS0 C19 C2I   25734075.834 L2I  134004287.472    0 D2I       2607.207 S2I   39.375 C6I   25734062.383 L6I  108889463.904    0 S6I   41.125
    CUT000AUS0 C20 C2I   22171840.147 L2I  115454153.788    0 D2I        259.834 S2I   50.688 C6I   22171825.517 L6I   93815970.330    0 S6I   50.000
    CUT000AUS0 C23 C2I   24439012.163 L2I  127260830.033    0 D2I      -2096.363 S2I   44.688 C6I   24438995.765 L6I  103409879.739    0 S6I   44.875
    CUT000AUS0 C28 C2I   25427888.185 L2I  132409857.631    0 D2I       2314.521 S2I   38.625 C6I   25427881.814 L6I  107593860.548    0 S6I   38.688

    > 2235 161042.0000000
    ..

The source code for BNC comes with a Perl script named 'test_tcpip_client.pl' that allows to read BNC's (synchronized or unsynchronized) ASCII observation output from the IP port and print it on standard output for verification.

Note that any socket connection of an application to BNC's synchronized or unsynchronized observation ports is recorded in the 'Log' tab on the bottom of the main window together with a connection counter, resulting in log records like 'New client connection on sync/usync port: # 1'.

The following figure shows the screenshot of a BNC configuration where a number of streams is pulled from different Ntrip Broadcasters to feed a GNSS engine via IP port output.

Figure 18: Synchronized BNC output via IP port to feed a GNSS real-time engine

#### 2.9.1 Port - optional

BNC can produce synchronized observations in ASCII format on your local host (IP 127.0.0.1) through an IP 'Port'. Synchronized means that BNC collects all observation data for a specific epoch, which become available within a certain number of seconds (see 'Wait for Full Obs Epoch' option). It then - epoch by epoch - outputs whatever has been received. The output comes block-wise per stream following the format specified in Table 2. Enter an IP port number here to activate this function. The default is an empty option field, meaning that no synchronized output is generated.

#### 2.9.2 Wait for Full Obs Epoch - mandatory if 'Port' is set

When feeding a real-time GNSS network engine waiting for synchronized observations epoch by epoch, BNC drops whatever is received later than 'Wait for full obs epoch' seconds. A value of 3 to 5 seconds could be an appropriate choice for that, depending on the latency of the incoming streams and the delay acceptable for your real-time GNSS product. Default value for 'Wait for full obs epoch' is 5 seconds. Note that 'Wait for full obs epoch' does not affect the RINEX Observation file content. Observations received later than 'Wait for full obs epoch' seconds will still be included in the RINEX Observation files.

#### 2.9.3 Sampling - mandatory if 'File' or 'Port' is set

Select a synchronized observation output sampling interval in seconds.

#### 2.9.4 File - optional

Specify the full path to a 'File' where synchronized observations are saved in plain ASCII format. The default value is an empty option field, meaning that no ASCII output file is created. Beware that the size of this file can rapidly increase depending on the number of incoming streams. To prevent it from becoming too large, the name of the file can be changed on-the-fly. This option is primarily meant for test and evaluation.

#### 2.9.5 Port (unsynchronized) - optional

BNC can produce unsynchronized observations from all configured streams in ASCII format on your local host (IP 127.0.0.1) through an IP 'Port'. Unsynchronized means that BNC immediately forwards any received observation to the port. Nevertheless, the output is produced block-wise per stream. Specify an IP port number here to activate this function. The default is an empty option field, meaning that no unsynchronized output is generated.

The following is an example for unsynchronized IP port output which presents observations from GPS, GLONASS, Galileo, BDS (BeiDou) as collected through stream WTZR00DEU0. The format for synchronized and unsynchronized output of observations is very much the same. However, unsynchronized output does not have 'Epoch Records' and 'Observation Records'. Instead each record contains the 'GPS Week Number' and 'GPS Second of Week' time tag between the mountpoint string and the satellite number, see Table 2 for format details.

    WTZR00DEU0 2235 163641.0000000 C45 C2I   21792728.974 L2I  113480606.233    0 D2I       -840.222 S2I   49.000 C6I   21792718.056 L6I   92212301.720    0 D6I       -682.735 S6I   53.000 C5P   21792722.630 L5P   85519518.841    0 D5P       -633.150 S5P   55.000 C1P   21792728.867 L1P  114521718.308    0 D1P       -847.940 S1P   49.000
    WTZR00DEU0 2235 163641.0000000 C57 C2I   35241541.940 L2I  183511967.699    0 D2I       3312.134 S2I   38.000
    WTZR00DEU0 2235 163641.0000000 C60 C2I   40835714.048 L2I  212642400.538    0 D2I          3.107 S2I   42.000 C6I   40835695.000 L6I  172789282.775    0 D6I          2.563 S6I   38.000
    WTZR00DEU0 2235 163642.0000000 G02 C1C   21379575.238 L1C  112350466.503    0 D1C       1170.040 S1C   50.000 C2W   21379571.878 L2W   87545832.377    0 D2W        911.720 S2W   48.000
    WTZR00DEU0 2235 163642.0000000 G04 C1C   25299844.801 L1C  132951592.093    0 D1C       1200.923 S1C   39.000 C2W   25299844.872 L2W  103598643.930    0 D2W        935.786 S2W   37.000 C2S   25299845.337 L2S  103598633.949    0 D2S        935.788 S2S   39.000 C5Q   25299848.214 L5Q   99282039.251    0 D5Q        896.700 S5Q   41.000
    ..
    WTZR00DEU0 2235 163642.0000000 R02 C1C   24526502.578 L1C  130878135.690    0 D1C      -3106.188 S1C   46.000 C2C   24526504.954 L2C  101794134.136    0 D2C      -2415.923 S2C   38.000 C2P   24526504.597 L2P  101794114.124    0 D2P      -2415.924 S2P   38.000
    WTZR00DEU0 2235 163642.0000000 R03 C1C   23652572.765 L1C  126614077.711    0 D1C       -630.104 S1C   46.000 C2C   23652573.301 L2C   98477638.096    0 D2C       -490.081 S2C   37.000 C2P   23652572.533 L2P   98477618.066    0 D2P       -490.085 S2P   37.000
    ..
    WTZR00DEU0 2235 163642.0000000 E01 C1C   26930045.201 L1C  141518526.177    0 D1C      -2534.602 S1C   49.000 C6C   26930047.720 L6C  114869006.985    0 D6C      -2057.304 S6C   50.000 C7Q   26930046.237 L7Q  108436367.651    0 D7Q      -1942.054 S7Q   45.000 C8Q   26930048.024 L8Q  107057942.802    0 D8Q      -1917.406 S8Q   50.000 C5Q   26930049.615 L5Q  105679526.128    0 D5Q      -1892.741 S5Q   48.000
    WTZR00DEU0 2235 163642.0000000 E03 C1C   28229782.305 L1C  148348501.362    0 D1C         39.942 S1C   44.000 C6C   28229782.234 L6C  120412744.902    0 D6C         32.553 S6C   43.000 C7Q   28229784.789 L7Q  113669639.982    0 D7Q         30.900 S7Q   42.000 C8Q   28229784.985 L8Q  112224686.556    0 D8Q         30.503 S8Q   44.000 C5Q   28229786.004 L5Q  110779744.311    0 D5Q         30.132 S5Q   40.000
    WTZR00DEU0 2235 163642.0000000 E05 C1C   27821824.684 L1C  146204675.792    0 D1C      -2023.955 S1C   45.000 C6C   27821825.542 L6C  118672628.805    0 D6C      -1642.884 S6C   44.000 C7Q   27821828.187 L7Q  112026972.544    0 D7Q      -1550.945 S7Q   44.000 C8Q   27821828.937 L8Q  110602896.522    0 D8Q      -1531.222 S8Q   46.000 C5Q   27821830.688 L5Q  109178838.676    0 D5Q      -1511.462 S5Q   43.000
    WTZR00DEU0 2235 163642.0000000 E10 C1C   27845624.132 L1C  146329752.236    0 D1C       3297.279 S1C   45.000 C6C   27845627.045 L6C  118774160.378    0 D6C       2676.374 S6C   45.000 C7Q   27845628.224 L7Q  112122811.041    0 D7Q       2526.467 S7Q   43.000 C8Q   27845628.510 L8Q  110697518.817    0 D8Q       2494.409 S8Q   46.000 C5Q   27845629.171 L5Q  109272236.786    0 D5Q       2462.268 S5Q   44.000
    WTZR00DEU0 2235 163642.0000000 E12 C1C   25724560.188 L1C  135183502.970    0 D1C       2910.137 S1C   46.000 C6C   25724557.561 L6C  109726872.278    0 D6C       2362.124 S6C   47.000 C7Q   25724559.313 L7Q  103582176.389    0 D7Q       2229.792 S7Q   46.000 C8Q   25724560.152 L8Q  102265454.924    0 D8Q       2201.438 S8Q   49.000 C5Q   25724561.117 L5Q  100948736.643    0 D5Q       2173.094 S5Q   46.000
    WTZR00DEU0 2235 163642.0000000 E24 C1C   24759911.740 L1C  130114254.885    0 D1C       1790.491 S1C   51.000 C6C   24759911.615 L6C  105612232.912    0 D6C       1453.295 S6C   54.000 C7Q   24759910.847 L7Q   99697952.062    0 D7Q       1371.869 S7Q   53.000 C8Q   24759912.151 L8Q   98430607.507    0 D8Q       1354.441 S8Q   55.000 C5Q   24759913.206 L5Q   97163270.129    0 D5Q       1337.013 S5Q   52.000
    WTZR00DEU0 2235 163642.0000000 E26 C1C   26508097.314 L1C  139301027.368    0 D1C      -2155.856 S1C   48.000 C6C   26508097.725 L6C  113069021.925    0 D6C      -1749.953 S6C   50.000 C7Q   26508097.279 L7Q  106737162.256    0 D7Q      -1651.940 S7Q   49.000 C8Q   26508097.904 L8Q  105380335.094    0 D8Q      -1630.981 S8Q   51.000 C5Q   26508099.012 L5Q  104023515.114    0 D5Q      -1610.036 S5Q   48.000
    ..
    WTZR00DEU0 2235 163642.0000000 C26 C2I   23510858.851 L2I  122427226.293    0 D2I       2283.809 S2I   49.000 C6I   23510855.528 L6I   99482138.474    0 D6I       1855.875 S6I   49.000 C5P   23510859.888 L5P   92261680.179    0 D5P       1721.110 S5P   50.000 C1P   23510858.387 L1P  123550408.663    0 D1P       2304.891 S1P   48.000
    WTZR00DEU0 2235 163642.0000000 C29 C2I   21580712.838 L2I  112376488.453    0 D2I        208.852 S2I   49.000 C6I   21580707.799 L6I   91315102.976    0 D6I        169.736 S6I   52.000 C5P   21580712.266 L5P   84687416.320    0 D5P        157.427 S5P   54.000 C1P   21580712.373 L1P  113407458.870    0 D1P        210.745 S1P   48.000
    WTZR00DEU0 2235 163642.0000000 C30 C2I   23959205.575 L2I  124761931.366    0 D2I      -2657.024 S2I   49.000 C6I   23959203.305 L6I  101379299.287    0 D6I      -2159.002 S6I   48.000 C5P   23959207.880 L5P   94021152.637    0 D5P      -2002.326 S5P   49.000 C1P   23959204.699 L1P  125906536.640    0 D1P      -2681.458 S1P   49.000
    ..
    WTZR00DEU0 2235 163642.0000000 C60 C2I   40835713.423 L2I  212642397.246    0 D2I          3.174 S2I   42.000 C6I   40835694.374 L6I  172789280.110    0 D6I          2.705 S6I   38.000
    WTZR00DEU0 2235 163643.0000000 G02 C1C   21379352.625 L1C  112349296.717    0 D1C       1169.503 S1C   50.000 C2W   21379349.266 L2W   87544920.854    0 D2W        911.301 S2W   49.000
    WTZR00DEU0 2235 163643.0000000 G04 C1C   25299616.345 L1C  132950391.648    0 D1C       1200.111 S1C   38.000 C2W   25299616.506 L2W  103597708.514    0 D2W        935.153 S2W   37.000 C2S   25299616.935 L2S  103597698.549    0 D2S        935.156 S2S   39.000 C5Q   25299619.758 L5Q   99281142.802    0 D5Q        896.365 S5Q   41.000
    ...

#### 2.10 Serial Output

You may use BNC to feed a serially connected device like a GNSS receiver. For that, an incoming stream can be forwarded to a serial port. Depending on the stream content, the receiver may use it for Differential GNSS, Precise Point Positioning or any other purpose supported by its firmware.

Note that receiving a VRS stream requires the receiver sending NMEA sentences (option 'NMEA' set to 'Manual' or 'Auto') to the Ntrip Broadcaster. The following figure shows the data flow when pulling a VRS stream or a physical (non-VRS) stream.

Figure 19: Flowcharts, BNC forwarding a stream to a serially connected receiver; sending NMEA sentences is mandatory for VRS streams

The following figure shows the screenshot of an example situation where BNC pulls a VRS stream from an Ntrip Broadcaster to feed a serially connected RTK rover.

Figure 20: BNC pulling a RTCM Version 3 stream to feed a serial connected receiver with observations from a nearby reference station for conventional RTK

#### 2.10.1 Mountpoint - optional

Enter a 'Mountpoint' to forward its corresponding stream to a serially connected GNSS receiver.

When selecting one of the serial communication options listed below, make sure that you pick those configured to the serially connected receiver.

#### 2.10.2 Port Name - mandatory if 'Mountpoint' is set

Enter the serial 'Port name' selected on your host for communication with the serially connected receiver. Valid port names are

Windows: | COM1, COM2
Linux: | /dev/ttyS0, /dev/ttyS1
FreeBSD: | /dev/ttyd0, /dev/ttyd1
Digital Unix: | /dev/tty01, /dev/tty02
HP-UX: | /dev/tty1p0, /dev/tty2p0
SGI/IRIX: | /dev/ttyf1, /dev/ttyf2
SunOS/Solaris: | /dev/ttya, /dev/ttyb

Note that you must plug a serial cable in the port defined here before you start BNC.

#### 2.10.3 Baud Rate - mandatory if 'Mountpoint' is set

Select a 'Baud rate' for the serial output link. Note that using a high baud rate is recommended.

#### 2.10.4 Flow Control - mandatory if 'Mountpoint' is set

Select a 'Flow control' for the serial output link. Note that your selection must equal the flow control configured to the serially connected device. Select 'OFF' if you do not know better.

#### 2.10.5 Parity - mandatory if 'Mountpoint' is set

Select the 'Parity' for the serial output link. Note that parity is often set to 'NONE'.

#### 2.10.6 Data Bits - mandatory if 'Mountpoint' is set

Select the number of 'Data bits' for the serial output link. Note that often '8' data bits are used.

#### 2.10.7 Stop Bits - mandatory if 'Mountpoint' is set

Select the number of 'Stop bits' for the serial output link. Note that often '1' stop bit is used.

#### 2.10.8 NMEA - mandatory if 'Mountpoint' is set

The 'NMEA' option supports the so-called 'Virtual Reference Station' (VRS) concept which requires the receiver to send approximate position information to the Ntrip Broadcaster. Select 'no' if you do not want BNC to forward or upload any NMEA sentence to the Ntrip broadcaster in support of VRS.

Select 'Auto' to automatically forward NMEA sentences of type GGA from your serially connected receiver to the Ntrip broadcaster and/or save them in a file.

Select 'Manual GPGGA' or 'Manual GNGGA' if you want BNC to produce and upload GPGGA or GNGGA NMEA sentences to the Ntrip broadcaster because your serially connected receiver does not generate them. A Talker ID 'GP' proceeding the GGA string stands for GPS solutions while a Talker ID 'GN' stands for multi-constellation solutions.

Note that selecting 'Auto' or 'Manual' works only for VRS streams which show up under the 'Streams' canvas on BNC's main window with 'nmea' stream attribute set to 'yes'. This attribute is either extracted from the Ntrip broadcaster's source-table or introduced by the user through editing the BNC configuration file.

#### 2.10.9 File - optional if 'NMEA' is set to 'Auto'

Specify the full path to a file where NMEA sentences coming from your serially connected receiver are saved. Default is an empty option field, meaning that no NMEA sentences will be saved on disk.

#### 2.10.10 Height - mandatory if 'NMEA' is set to 'Manual'

Specify an approximate 'Height' above mean sea level in meters for the reference station introduced through 'Mountpoint'. Together with the latitude and longitude from the Ntrip broadcaster source-table, the height information is used to build GGA sentences to be sent to the Ntrip broadcaster.

For adjusting latitude and longitude values of a VRS stream given in the 'Streams' canvas, you can double click the latitude/longitude data fields, specify appropriate values and then hit Enter.

This option is only relevant when option 'NMEA' is set to 'Manual GPGGA' or 'Manual GNGGA' respectively.

#### 2.10.11 Sampling - mandatory if 'NMEA' is set to 'Manual'

Select a sampling interval in seconds for manual generation and upload of NMEA GGA sentences.

A sampling rate of '0' means that a GGA sentence will be sent only once to initialize the requested VRS stream. Note that some VRS systems need GGA sentences at regular intervals.

#### 2.11 Outages

At any time an incoming stream might become unavailable or corrupted. In such cases, it is important that the BNC operator and/or the stream providers become aware of the situation so that measures can be taken to restore the stream. Furthermore, continuous attempts to decode a corrupted stream can generate unnecessary workload for BNC. Outages and corruptions are handled by BNC as follows:

Stream outages: BNC considers a connection to be broken when there are no incoming data detected for more than 20 seconds. When this occurs, BNC will try to reconnect at a decreasing rate. It will first try to reconnect with 1 second delay and again in 2 seconds if the previous attempt failed. If the attempt is still unsuccessful, it will try to reconnect within 4 seconds after the previous attempt and so on. The waiting time doubles each time with a maximum of 256 seconds.

Stream corruption: Not all chunks of bits transferred to BNC's internal decoder may return valid observations. Sometimes several chunks might be needed before the next observation can be properly decoded. BNC buffers all outputs (both valid and invalid) from the decoder for a short time span (size derived from the expected 'Observation rate') to then determine whether a stream is valid or corrupted.

Outage and corruption events are reported in the 'Log' tab. They can also be passed on as parameters to a shell script or batch file to generate an advisory note to BNC's operator or affected stream providers. This functionality lets users utilize BNC as a real-time performance monitor and alarm system for a network of GNSS reference stations.

#### 2.11.1 Observation Rate - optional

BNC can collect all returns (success or failure) coming from a decoder within a certain short time span to then decide whether a stream has an outage or its content is corrupted. This procedure needs a rough a priori estimate of the expected observation rate of the incoming streams.

An empty option field (default) means that you do not want explicit information from BNC about stream outages and incoming streams that cannot be decoded.

#### 2.11.2 Failure Threshold - mandatory if 'Observation rate' is set

Event 'Begin_Failure' will be reported if no data is received continuously for longer than the 'Failure threshold' time. Similarly, event 'Begin_Corrupted' will be reported when corrupted data is detected by the decoder continuously for longer than this 'Failure threshold' time. The default value is set to 15 minutes and is recommended as to not inundate users with too many event reports.

Note that specifying a value of zero '0' for the 'Failure threshold' will force BNC to report any stream failure immediately. Note also that for using this function you need to specify the 'Observation rate'.

#### 2.11.3 Recovery Threshold - mandatory if 'Observation rate' is set

Once a 'Begin_Failure' or 'Begin_Corrupted' event has been reported, BNC will check when the stream again becomes available or uncorrupted. Event 'End_Failure' or 'End_Corrupted' will be reported as soon as valid observations are detected continuously throughout the 'Recovery threshold' time span. The default value is set to 5 minutes and is recommended as to not inundate users with too many event reports.

Note that specifying a value of zero '0' for the 'Recovery threshold' will force BNC to report any stream recovery immediately. Note also that for using this function you need to specify the 'Observation rate'.

#### 2.11.4 Script - optional if 'Observation rate' is set

As mentioned before, BNC can trigger a shell script or a batch file to be executed when one of the described events is reported. This script can be used to email an advisory note to network operator or stream providers. To enable this feature, specify the full path to the script or batch file in the 'Script' field. The affected stream's mountpoint and type of event reported ('Begin_Outage', 'End_Outage', 'Begin_Corrupted' or 'End_Corrupted') will then be passed on to the script as command line parameters (%1 and %2 on Windows systems or $1 and $2 on Unix/Linux/Mac OS X systems) together with date and time information.

Leave the 'Script' field empty if you do not wish to use this option. An invalid path will also disable this option.

Examples for command line parameter strings passed on to the advisory 'Script' are:

       FFMJ00DEU0 Begin_Outage 22-02-21 09:25:59
       FFMJ00DEU0 End_Outage 22-02-21 11:36:02 Begin was 22-02-21 09:25:59

Sample script for Unix/Linux/Mac OS X systems:

       #!/bin/bash
       sleep $((60*RANDOM/32767))
       cat > mail.txt <<EOF
       Advisory Note to BNC User,
       Please note the following advisory received from BNC.
       Stream: $*
       Regards, BNC
       EOF
       mail -s "NABU: $1" email@address < mail.txt

Note the sleep command in this script, which causes the system to wait for a random period of up to 60 seconds before sending the email. This should avoid overloading your mail server in case of a simultaneous failure of many streams.

#### 2.12 Miscellaneous

This section describes several miscellaneous options which can be applied to a single stream (mountpoint) or to all configured streams.

The following figure shows RTCM message numbers and observation types contained in stream 'CUT000AUS0' and the message latencies recorded every 2 seconds.

Figure 21: RTCM message numbers, latencies and observation types logged by BNC

#### 2.12.1 Mountpoint - optional

Specify a mountpoint to apply one or several of the 'Miscellaneous' options to the corresponding stream. Enter 'ALL' if you want to apply these options to all configured streams. An empty option field (default) means that you do not want BNC to apply any of these options.

#### 2.12.2 Log Latency - optional

BNC can average latencies per stream over a certain period of GPS time, the 'Log latency' interval. Mean latencies are calculated from the individual latencies of one (first incoming) observation or Broadcast Correction per second. The mean latencies are then saved in BNC's logfile. Note that computing correct latencies requires the clock of the host computer to be properly synchronized. Note further that visualized latencies from the 'Latency' tab on the bottom of the main window represent individual latencies and not the mean latencies for the logfile.

Latency: Latency is defined in BNC by the following equation:

        UTC time provided by BNC's host
      - GPS time of currently processed epoch
      + Leap seconds between UTC and GPS time
      --------------
      = Latency

Statistics: BNC counts the number of GPS seconds covered by at least one observation. It also estimates an observation rate (independent from the a priori specified 'Observation rate') from all observations received throughout the first full 'Log latency' interval. Based on this rate, BNC estimates the number of data gaps when appearing in subsequent intervals.

Latencies of observations or corrections to Broadcast Ephemeris and statistical information can be recorded in the 'Log' tab at the end of each 'Log latency' interval. A typical output from a 1 hour 'Log latency' interval would be:

    22-11-09 11:59:42 CUT000AUS0 Observations: Mean latency 0.48 sec, min 0.25, max 0.97, rms 0.50, 3600 epochs, 0 gaps

Select a 'Log latency' interval to activate this function or select the empty option field if you do not want BNC to log latencies and statistical information.

#### 2.12.3 Scan RTCM - optional

When configuring a GNSS receiver for RTCM stream generation, the firmware's setup interface may not provide details about RTCM message types and observation types. As reliable information concerning stream content should be available e.g. for Ntrip Broadcaster operators to maintain the broadcaster's source-table, BNC allows to scan RTCM streams for incoming message types and printout some of the contained meta-data. Contained observation types are also printed because such information is required a priori for the conversion of RTCM Version 3 MSM streams to RINEX Version 3 files.

Tick 'Scan RTCM' to scan RTCM Version 2 or 3 streams and log all contained

- Numbers of incoming message types
- Antenna Reference Point (ARP) coordinates
- Antenna Phase Center (APC) coordinates
- Antenna height above marker
- Antenna descriptor.

In case of RTCM Version 3 streams the output includes

- RINEX Version 3 Observation types

Note that in RTCM Version 2 message types 18 and 19 carry only the observables of one frequency. Hence it needs two type 18 and 19 messages per epoch to transport observations from dual frequency receivers.

Please note further that RTCM Version 3 message types 1084 for GLONASS do not contain GLONASS channel numbers. The same is true for most of the GLONASS MSM messages, expect for MSM5 and MSM7, where the GLONASS channel number is available as extended information. Such observations can only be decoded when you include 1020 GLONASS ephemeris messages to your stream, which contain the channels. You could also add another stream carrying 1087 GLONASS observation messages or 1020 GLONASS ephemeris messages to get the GLONASS channel numbers.

Logged time stamps refer to message reception time and allow understanding repetition rates. Enter 'ALL' if you want to log this information from all configured streams. Beware that the size of the logfile can rapidly increase depending on the number of incoming RTCM streams.

This option is primarily meant for test and evaluation. Use it to figure out what exactly is produced by a specific GNSS receiver's configuration. An empty option field (default) means that you do not want BNC to print message type numbers and antenna information carried in RTCM streams.

#### 2.12.4 Port - optional

BNC can output streams related to the above specified 'Mountpoint' through a TCP/IP port of your local host. Enter a port number to activate this function. The stream content remains untouched. BNC does not decode or reformat the data for this output.

An empty option field (default) means that you do not want BNC to apply the TCP/IP port output option.

#### 2.13 PPP Client

BNC can derive coordinates for rover positions following different Precise Point Positioning (PPP) methods:

- Uncombined PPP
- Ionosphere-free PPP

Therefore it uses code data (Pi), phase data (Li) or code&phase data (Pi&Li) from one or more GNSS. Besides pulling streams of observations from a dual frequency GNSS receiver, this

- Requires pulling in addition a stream carrying satellite orbit and clock corrections to Broadcast Ephemeris in the form of RTCM-SSR or IGS-SSR messages. Note that for BNC these Broadcast Corrections need to be referred to the satellite's Antenna Phase Center (APC). Streams providing such messages are listed on https://igs.bkg.bund.de/ntrip/#rtcm-corr Stream 'SSRA00BKG0' (RTCM-SSR) or 'SSRA00BKG1' (IGS-SSR) on Ntrip Broadcaster 'products.igs-ip.net:2101' is an example.
- May require pulling a stream carrying Broadcast Ephemeris available as RTCM Version 3 message types 1019, 1020, 1043, 1044, 1045, 1046, etc.. This becomes a must only when the stream coming from the receiver does not contain Broadcast Ephemeris or provides them only at very low repetition rate. Streams providing such messages are listed on https://igs.bkg.bund.de/ntrip/#rtcm-eph Stream 'BCEP00BKG0' on caster 'products.igs-ip.net:2101' is an example.

Note that Broadcast Ephemeris parameters pass a plausibility check in BNC which allows to ignore incorrect or outdated ephemeris data when necessary, leaving a note 'WRONG EPHEMERIS' or 'OUTDATED EPHEMERIS' in the logfile. Unhealthy ephemeris data sets are remaining and leaving a note 'UNHEALTHY' in the logfile. When using the PPP option, BNC does correct for:

- Solid Earth Tides and Phase Windup
- Satellite Antenna Phase Center offsets and variations
- Receiver Antenna Phase Center offsets and variations: Depending on whether or not these corrections are applied, the estimated position is either that of the receiver's Antenna Phase Center or that of the receiver's Antenna Reference Point
- Ocean and atmospheric loading: Atmospheric loading is pretty small but Ocean loading may reach up to about 10 centimeters for coastal stations

Rotational deformation due to polar motion (Polar Tides) is not corrected because this is a small effect usually less than 2 centimeters.

The provider of an orbit/clock correction stream may switch with his service at any time from a duty to a backup server installation. This shall be noted in the SSR stream through a change of the Issue Of Data (IOD SSR) parameter. The PPP option in BNC will immediately reset all ambiguities in such a situation.

PPP options are specified in BNC through the following four panels.

- PPP (1): Input and output, specifying real-time or post processing mode and associated data sources
- PPP (2): Processing options, specifying general PPP processing options
- PPP (3): Processed stations, specifying sigmas and noise of a priori coordinates and troposphere paremeters, NMEA stream output and signal priorities
- PPP (4): Plots, specifying visualization through time series and track maps

#### 2.13.1 PPP (1): Input and Output

This panel provides options for specifying the input and output streams and files required by BNC for real-time or post processing PPP.

Figure 22: Real-time Precise Point Positioning with BNC, PPP Panel 1

#### 2.13.1.1 Data Source - optional

Choose between input from 'Real-time Streams' or 'RINEX Files' for PPP with BNC in real-time or post processing mode.

Real-time Streams: When choosing 'Real-time Streams' BNC will do PPP solutions in real-time. This requires pulling GNSS observation streams, Broadcast Ephemeris messages and a stream containing corrections to Broadcast Ephemerides. Streams with observation and navigation data have to be in RTCM Version 3 format. Correction streams have to be in RTCM-SSR or IGS-SSR format. If you do not pull Broadcast Corrections, BNC will switch with its solution to 'Single Point Positioning' (SPP) mode.

RINEX Files: This input mode allows to specify RINEX Observation, RINEX Navigation and Broadcast Correction files. BNC accepts RINEX Version 2 as well as RINEX Version 3 Observation or Navigation file formats. Files carrying Broadcast Corrections must have the format produced by BNC through the 'Broadcast Corrections' panel. Specifying only a RINEX Observation and a RINEX Navigation file and no Broadcast Correction file leads BNC to a 'Single Point Positioning' (SPP) solution.

Note that for debugging purposes, BNC's real-time PPP functionality can also be used offline. Apply the 'File Mode' 'Command Line' option for that to read a file containing synchronized observations, orbit and clock correctors, and Broadcast Ephemeris. Example:

    	Windows: bnc.exe --conf c:\temp\PPP.bnc --file c:\temp\RAW

Such a file (here: 'RAW') must be saved beforehand using BNC's 'Raw output file' option.

#### 2.13.1.2 Corrections Stream - optional if 'Data source' is set to 'Real-Time Streams'

Specify a Broadcast 'Corrections stream' from the list of selected 'Streams' you are pulling if you want BNC to correct your satellite ephemeris and observations accordingly. Note that the stream's orbit and clock corrections must refer to the satellite Antenna Phase Center (APC). Streams providing such corrections are made available e.g. through the International GNSS Service (IGS) and can for example be be pulled from https://products.igs-ip.net The stream format must be RTCM-SSR or IGS-SSR containing so-called SSR messages. Streams 'SSRA03IGS1' and 'SSRA00BKG1' are examples using the IGS-SSR format. If you do not specify a 'Corrections stream', BNC will fall back from a PPP solution to a Single Point Positioning (SPP) solution.

#### 2.13.1.3 Corrections File - optional if 'Data source' is set to 'RINEX Files'

Specify a Broadcast 'Corrections file' as saved beforehand using BNC. The file content is basically the ASCII representation of a RTCM-SSR or a IGS-SSR Broadcast Correction stream. If you do not specify a 'Correction file', BNC will fall back from a PPP solution to a Single Point Positioning (SPP) solution.

#### 2.13.1.4 Ionosphere Stream - optional if 'Data source' is set to 'Real-Time Streams'

Specify a 'Ionosphere stream' which provides VTEC informations in SSR format from the list of selected 'Streams' you are pulling if you want BNC to correct your observations accordingly. Streams providing such VTEC informations are made available e.g. through the International GNSS Service (IGS) and can for example be be pulled from https://products.igs-ip.net The stream format must be RTCM-SSR or IGS-SSR containing so-called SSR messages. Streams 'IONO00IGS1' and 'IONO00UPC1' are examples using the IGS-SSR format. If you do not specify a 'Ionosphere stream' via this option, BNC will use VTEC informations from the Corrections stream 'mountpoint', if available.

#### 2.13.1.5 Ionosphere File - optional if 'Data source' is set to 'RINEX Files'

Specify a 'Ionosphere file' as saved beforehand using BNC. The file content is basically the ASCII representation of a RTCM-SSR or a IGS-SSR Ionosphere stream.

#### 2.13.1.6 RINEX Observation File - mandatory if 'Data source' is set to 'RINEX Files'

Specify a RINEX Observation file. The file format can be RINEX Version 2, RINEX Version 3 or RINEX Version 4.

#### 2.13.1.7 RINEX Navigation File - mandatory if 'Data source' is set to 'RINEX Files'

Specify a RINEX Navigation file.The file format can be RINEX Version 2, RINEX Version 3 or RINEX Version 4.

#### 2.13.1.8 ANTEX File - optional

IGS provides a file containing absolute phase center corrections for GNSS satellite and receiver antennas in ANTEX format Version 1.4 (at https://kb.igs.org/hc/en-us/articles/216104678-ANTEX-format-description/). Such so-called ANTEX files are available from IGS through at https://files.igs.org/pub/station/general/. An example ANTEX file 'igs20.atx' is part of the BNC package for convenience.

Entering the full path to such an ANTEX file is required for correcting observations in PPP for Antenna Phase Center offsets and variations. Note that for applying such corrections you need to specify the receiver's antenna name and radome in BNC's 'Coordinates file'.

Default value for 'ANTEX file' is an empty option field, meaning that you do not want to correct observations for Antenna Phase Center offsets and variations.

#### 2.13.1.9 Coordinates File - optional

Enter the full path to an ASCII file which specifies all observation streams or files from stationary or mobile receivers you possibly may want to process.

Specifying a 'Coordinates file' is optional. If it exists, it should contain one record per stream or file with the following parameters separated by blank characters:

- Input data source, to be specified either through
  - the 'Mountpoint' of an RTCM stream (when in real-time PPP mode), or
  - the first four (RINEX Version 2) or nine (RINEX Version 3 and 4) characters of the RINEX observations file (when in post processing PPP mode).
  Having at least this first parameter in each record is mandatory.
- For static observations from a stationary receiver an approximate a priori XYZ coordinate [m] of the station's marker should be specified.
  If such an approximate a priori XYZ coordinate is unknown or when observations come from a mobile receiver, '0.0 0.0 0.0' shall be used instead.
- The North, East and Up component [m] of antenna eccentricity, which is the difference between the Antenna Reference Point (ARP) and a nearby marker position, can be specified.
  Please note, when specifying the antenna eccentricity, BNC will produce coordinates referring to the marker position and not referring to the ARP.
  If the eccentricity is unknown or the ARP itself is understood as the marker, '0.0 0.0 0.0' shall be specified instead.
- Receiver's antenna name as defined in your ANTEX file (see below). The specified name must consist of 20 characters. Add trailing blanks if the antenna name has less than 20 characters.
  Examples:

      		 'JPSREGANT_SD_E      ' (no radome)
      		 'LEIAT504        NONE' (no radome)
      		 'LEIAR25.R3      LEIT' (radome is LEIT)

  Observations will be corrected for the receiver Antenna Phase Center (APC) offsets and variations.
  Leave antenna name blank if you do not want to correct observations for APC offsets and variations or if you do not know the antenna name.
- Receiver type following the naming convention for IGS equipment as defined in https://files.igs.org/pub/station/general/rcvr_ant.tab.
- Specifying the receiver type is only required when saving SINEX Troposphere files. In those files it becomes part of the 'SITE/RECEIVER' specifications, see section 'SNX TRO Directory'.

Records in the 'Coordinates' file with exclamation mark '!' in the first column or blank records will be understood as comment lines and ignored.

The following is the content of an example 'Coordinates file'. Here each record describes the mountpoint of a stream available from the global IGS real-time reference station network. A priori coordinates are followed by North/East/Up eccentricity components of the ARP, followed by the antenna name and radome in use, and followed by the receiver name.

    ! --------------------------------------------------------------------------------------------------------------------------------!
    ! Apriori coordinates with eccentricities, antenna and receiver, Reference System IGS20
    ! --------------------------------------------------------------------------------------------------------------------------------!
    ! Station       X[m]            Y[m]          Z[m]          North[m]   EAST[m]    UP[m]   Antenna_______Radom Receiver
    ! --------------------------------------------------------------------------------------------------------------------------------!
    ! REAL-TIME !
    FFMJ00DEU0 4053455.62808   617729.94590  4869395.88436      0.0000     0.0000     0.0450  LEIAR25.R4     LEIT JAVAD TRE_G3TH DELTA
    FFMJ01DEU0 4053455.62808   617729.94590  4869395.88436      0.0000     0.0000     0.0450  LEIAR25.R4     LEIT LEICA GR50
    WTZR00DEU0 4075580.27823   931854.08861  4801568.30495      0.0000     0.0000     0.0710  LEIAR25.R3     LEIT LEICA GR25
    ! RINEX !
    FFMJ00DEU  4053455.62808   617729.94590  4869395.88436      0.0000     0.0000     0.0450  LEIAR25.R4     LEIT JAVAD TRE_G3TH DELTA
    FFMJ01DEU  4053455.62808   617729.94590  4869395.88436      0.0000     0.0000     0.0450  LEIAR25.R4     LEIT LEICA GR50
    WTZR00DEU  4075580.27823   931854.08861  4801568.30495      0.0000     0.0000     0.0710  LEIAR25.R3     LEIT LEICA GR25
    VM01             0.0            0.0            0.0          0.0000     0.0000     0.0000
    ! REAL-TIME TEST !
    TRDS00NOR0 2820170.56469  513486.25161  5678936.13675      5.5460     0.0070     0.0180 TRM55971.00     NONE TRIMBLE NETR9

In this file

- Record 'FFMJ00DEU0' describes a stream from a stationary receiver with known a priori marker coordinates, antenna eccentricities, antenna and radome type, and receiver type.
- Record 'FFMJ00DEU' indicates that a RINEX version 3 or 4 observations file for post processing PPP is available for station 'FFMJ00DEU' with known a priori marker coordinates, antenna eccentricities, antenna and radome type, and receiver type.
- The 4-character station ID 'VM01' indicates that a RINEX version 2 observations file, resultant from a mobile rover receiver, is available for post processing PPP. Hence a priori coordinates are unknown although antenna eccentricities, antenna and radome type, and receiver type are known.
- Record 'TRDS00NOR0' describes a stream from a stationary receiver with known a priori marker coordinates, antenna eccentricities, antenna and receiver type but without radom.

Note again that the only mandatory parameters in this file are the 'Station' parameters in the first column, each standing for an observation stream's mountpoint or the 9/4-character station ID of a RINEX filename.

#### 2.13.1.10 BLQ File - optional

Specify a 'BLQ file' containing the ocean loading coefficients for all stations you want to process. These coefficients can be obtained from the ocean loading service under request trough the web site http://holt.oso.chalmers.se/loading/ . BNC computes time series of tidal displacements for the respective stations using that input file.

#### 2.13.1.11 Logfile Directory - optional

Essential PPP results are shown in the 'Log' tab on the bottom of BNC's main window. Depending on the processing options, the following values are presented about once per second (example):

    ...
    23-06-16 09:38:14 2023-06-16_09:38:02.000 WTZR00DEU0 X = 4075580.2757 Y = 931854.0947 Z = 4801568.3115 NEU:  +0.0052  +0.0065  +0.0043 TRP:  +2.1833  +0.0128
    23-06-16 09:38:14 2023-06-16_09:38:03.000 WTZR00DEU0 X = 4075580.2734 Y = 931854.0948 Z = 4801568.3062 NEU:  +0.0033  +0.0072  -0.0012 TRP:  +2.1833  +0.0124
    23-06-16 09:38:14 2023-06-16_09:38:04.000 WTZR00DEU0 X = 4075580.2759 Y = 931854.0955 Z = 4801568.3077 NEU:  +0.0023  +0.0073  +0.0016 TRP:  +2.1833  +0.0119
    23-06-16 09:38:18 2023-06-16_09:38:05.000 WTZR00DEU0 X = 4075580.2766 Y = 931854.0948 Z = 4801568.3106 NEU:  +0.0039  +0.0064  +0.0042 TRP:  +2.1833  +0.0126
    23-06-16 09:38:18 2023-06-16_09:38:06.000 WTZR00DEU0 X = 4075580.2762 Y = 931854.0953 Z = 4801568.3125 NEU:  +0.0053  +0.0070  +0.0054 TRP:  +2.1833  +0.0121
    23-06-16 09:38:18 2023-06-16_09:38:07.000 WTZR00DEU0 X = 4075580.2796 Y = 931854.0948 Z = 4801568.3169 NEU:  +0.0058  +0.0058  +0.0108 TRP:  +2.1833  +0.0106
    23-06-16 09:38:18 2023-06-16_09:38:08.000 WTZR00DEU0 X = 4075580.2780 Y = 931854.0947 Z = 4801568.3153 NEU:  +0.0059  +0.0059  +0.0085 TRP:  +2.1833  +0.0103
    23-06-16 09:38:18 2023-06-16_09:38:09.000 WTZR00DEU0 X = 4075580.2828 Y = 931854.0955 Z = 4801568.3186 NEU:  +0.0044  +0.0057  +0.0142 TRP:  +2.1833  +0.0089
    23-06-16 09:38:23 2023-06-16_09:38:10.000 WTZR00DEU0 X = 4075580.2806 Y = 931854.0966 Z = 4801568.3160 NEU:  +0.0041  +0.0073  +0.0110 TRP:  +2.1833  +0.0091
    23-06-16 09:38:23 2023-06-16_09:38:11.000 WTZR00DEU0 X = 4075580.2849 Y = 931854.0983 Z = 4801568.3197 NEU:  +0.0031  +0.0080  +0.0168 TRP:  +2.1833  +0.0090
    23-06-16 09:38:23 2023-06-16_09:38:12.000 WTZR00DEU0 X = 4075580.2840 Y = 931854.0974 Z = 4801568.3199 NEU:  +0.0040  +0.0073  +0.0163 TRP:  +2.1833  +0.0083

    ...

Each row reports the PPP result of one epoch. It begins with a UTC time stamp (yy-mm-dd hh:mm:ss) which tells us when the result was produced. A second time stamp (yyyy-mm-dd_hh:mm:ss) describes the PPP's epoch in 'GPS Time'. It is followed by the derived XYZ position in [m], its North, East and Up displacement compared to an introduced a priori coordinate, and the estimated tropospheric delay [m] (model plus correction).

If you require more information, you can specify a 'Logfile directory' to save daily logfiles per station (filename suffix 'ppp') with additional processing details on disk.

    PPP of Epoch 2023-06-16_09:38:14.000
    ---------------------------------------------------------------
    2023-06-16_09:38:14.000 BANCROFT:    4075581.143     931854.020    4801566.899       -980.475

    2023-06-16_09:38:14.000 SATNUM G 10
    2023-06-16_09:38:14.000 RES c1  G07  -0.0955
    2023-06-16_09:38:14.000 RES c1  G08  -0.2442
    2023-06-16_09:38:14.000 RES c1  G10  -0.3147
    2023-06-16_09:38:14.000 RES c1  G15  -0.1287
    2023-06-16_09:38:14.000 RES c1  G16   0.2312
    2023-06-16_09:38:14.000 RES c1  G18   0.0843
    2023-06-16_09:38:14.000 RES c1  G23   0.0766
    2023-06-16_09:38:14.000 RES c1  G26  -0.2298
    2023-06-16_09:38:14.000 RES c1  G27  -0.1050
    2023-06-16_09:38:14.000 RES c1  G29  -0.5383
    2023-06-16_09:38:14.000 RES c2  G07   0.0397
    2023-06-16_09:38:14.000 RES c2  G08   0.6023
    2023-06-16_09:38:14.000 RES c2  G10   0.1851
    2023-06-16_09:38:14.000 RES c2  G15   0.3041
    2023-06-16_09:38:14.000 RES c2  G16  -0.1406
    2023-06-16_09:38:14.000 RES c2  G18  -0.0338
    2023-06-16_09:38:14.000 RES c2  G23  -0.1413
    2023-06-16_09:38:14.000 RES c2  G26   0.0423
    2023-06-16_09:38:14.000 RES c2  G27   0.0964
    2023-06-16_09:38:14.000 RES c2  G29   0.3377
    2023-06-16_09:38:14.000 RES l1  G07   0.0023
    2023-06-16_09:38:14.000 RES l1  G08  -0.0032
    2023-06-16_09:38:14.000 RES l1  G10   0.0028
    2023-06-16_09:38:14.000 RES l1  G15   0.0004
    2023-06-16_09:38:14.000 RES l1  G16   0.0006
    2023-06-16_09:38:14.000 RES l1  G18  -0.0010
    2023-06-16_09:38:14.000 RES l1  G23  -0.0005
    2023-06-16_09:38:14.000 RES l1  G26  -0.0012
    2023-06-16_09:38:14.000 RES l1  G27   0.0011
    2023-06-16_09:38:14.000 RES l1  G29  -0.0014
    2023-06-16_09:38:14.000 RES l2  G07  -0.0014
    2023-06-16_09:38:14.000 RES l2  G08   0.0019
    2023-06-16_09:38:14.000 RES l2  G10  -0.0017
    2023-06-16_09:38:14.000 RES l2  G15  -0.0003
    2023-06-16_09:38:14.000 RES l2  G16  -0.0004
    2023-06-16_09:38:14.000 RES l2  G18   0.0006
    2023-06-16_09:38:14.000 RES l2  G23   0.0003
    2023-06-16_09:38:14.000 RES l2  G26   0.0007
    2023-06-16_09:38:14.000 RES l2  G27  -0.0006
    2023-06-16_09:38:14.000 RES l2  G29   0.0008
    2023-06-16_09:38:14.000 SATNUM R  6
    2023-06-16_09:38:14.000 RES c1  R03  -0.0766
    2023-06-16_09:38:14.000 RES c1  R04   0.0750
    2023-06-16_09:38:14.000 RES c1  R09  -0.3940
    2023-06-16_09:38:14.000 RES c1  R11  -0.5458
    2023-06-16_09:38:14.000 RES c1  R19   1.0069
    2023-06-16_09:38:14.000 RES c1  R20  -0.5371
    2023-06-16_09:38:14.000 RES c2  R03   0.1258
    2023-06-16_09:38:14.000 RES c2  R04   0.0652
    2023-06-16_09:38:14.000 RES c2  R09   0.2131
    2023-06-16_09:38:14.000 RES c2  R11   0.2516
    2023-06-16_09:38:14.000 RES c2  R19  -0.6786
    2023-06-16_09:38:14.000 RES c2  R20   0.2640
    2023-06-16_09:38:14.000 RES l1  R03   0.0084
    2023-06-16_09:38:14.000 RES l1  R04  -0.0078
    2023-06-16_09:38:14.000 RES l1  R09   0.0017
    2023-06-16_09:38:14.000 RES l1  R11  -0.0032
    2023-06-16_09:38:14.000 RES l1  R19   0.0026
    2023-06-16_09:38:14.000 RES l1  R20  -0.0016
    2023-06-16_09:38:14.000 RES l2  R03  -0.0051
    2023-06-16_09:38:14.000 RES l2  R04   0.0047
    2023-06-16_09:38:14.000 RES l2  R09  -0.0010
    2023-06-16_09:38:14.000 RES l2  R11   0.0019
    2023-06-16_09:38:14.000 RES l2  R19  -0.0016
    2023-06-16_09:38:14.000 RES l2  R20   0.0010
    2023-06-16_09:38:14.000 SATNUM E  6
    2023-06-16_09:38:14.000 RES c1  E08  -0.2999
    2023-06-16_09:38:14.000 RES c1  E13  -0.0223
    2023-06-16_09:38:14.000 RES c1  E21   0.1809
    2023-06-16_09:38:14.000 RES c1  E26  -0.0959
    2023-06-16_09:38:14.000 RES c1  E31   0.4252
    2023-06-16_09:38:14.000 RES c1  E33  -0.0854
    2023-06-16_09:38:14.000 RES c2  E08   0.3975
    2023-06-16_09:38:14.000 RES c2  E13   0.0378
    2023-06-16_09:38:14.000 RES c2  E21   0.0315
    2023-06-16_09:38:14.000 RES c2  E26   0.0774
    2023-06-16_09:38:14.000 RES c2  E31  -0.2201
    2023-06-16_09:38:14.000 RES c2  E33   0.2973
    2023-06-16_09:38:14.000 RES l1  E08  -0.0014
    2023-06-16_09:38:14.000 RES l1  E13  -0.0004
    2023-06-16_09:38:14.000 RES l1  E21   0.0001
    2023-06-16_09:38:14.000 RES l1  E26  -0.0009
    2023-06-16_09:38:14.000 RES l1  E31   0.0014
    2023-06-16_09:38:14.000 RES l1  E33   0.0010
    2023-06-16_09:38:14.000 RES l2  E08   0.0008
    2023-06-16_09:38:14.000 RES l2  E13   0.0002
    2023-06-16_09:38:14.000 RES l2  E21  -0.0001
    2023-06-16_09:38:14.000 RES l2  E26   0.0005
    2023-06-16_09:38:14.000 RES l2  E31  -0.0008
    2023-06-16_09:38:14.000 RES l2  E33  -0.0006

    2023-06-16_09:38:14.000 REC_CLK          0.0000    +1.0967 +-   0.5113
    2023-06-16_09:38:14.000 OFF_GLO          9.2689    -1.3615 +-   0.8276
    2023-06-16_09:38:14.000 OFF_GAL         -7.7011    -1.1984 +-   0.7445
    2023-06-16_09:38:14.000 TRP              2.1833    +0.0067 +-   0.0778
    2023-06-16_09:38:14.000 ION      G07     0.0000    +4.3732 +-   0.7184
    2023-06-16_09:38:14.000 ION      G08     0.0000    +4.8651 +-   0.6096
    2023-06-16_09:38:14.000 ION      G10     0.0000    +7.3252 +-   0.4895
    2023-06-16_09:38:14.000 ION      G15     0.0000    +9.1219 +-   0.7036
    2023-06-16_09:38:14.000 ION      G16     0.0000    +0.9363 +-   0.3971
    2023-06-16_09:38:14.000 ION      G18     0.0000    +2.2202 +-   0.4039
    2023-06-16_09:38:14.000 ION      G23     0.0000    +3.6510 +-   0.4177
    2023-06-16_09:38:14.000 ION      G26     0.0000    +3.1689 +-   0.4149
    2023-06-16_09:38:14.000 ION      G27     0.0000    +1.9841 +-   0.4181
    2023-06-16_09:38:14.000 ION      G29     0.0000   +11.4117 +-   0.7321
    2023-06-16_09:38:14.000 ION      R03     0.0000    +6.9111 +-   0.6325
    2023-06-16_09:38:14.000 ION      R04     0.0000    +9.2756 +-   0.6331
    2023-06-16_09:38:14.000 ION      R09     0.0000    +9.5771 +-   0.5909
    2023-06-16_09:38:14.000 ION      R11     0.0000    +7.6482 +-   0.6204
    2023-06-16_09:38:14.000 ION      R19     0.0000    +3.4002 +-   0.5535
    2023-06-16_09:38:14.000 ION      R20     0.0000    +6.6337 +-   0.5324
    2023-06-16_09:38:14.000 ION      E08     0.0000   +12.7456 +-   0.7221
    2023-06-16_09:38:14.000 ION      E13     0.0000    +6.6588 +-   0.4538
    2023-06-16_09:38:14.000 ION      E21     0.0000   +11.0861 +-   0.4918
    2023-06-16_09:38:14.000 ION      E26     0.0000    +5.3364 +-   0.4082
    2023-06-16_09:38:14.000 ION      E31     0.0000    +6.4918 +-   0.4624
    2023-06-16_09:38:14.000 ION      E33     0.0000    +8.4840 +-   0.4700
    2023-06-16_09:38:14.000 AMB  l1  G07    17.0000   +13.1981 +-   6.4136 el =   8.37 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G08    63.0000   +15.7514 +-   5.3459 el =  14.29 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G10   150.0000   +29.2629 +-   4.7714 el =  28.31 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G15    67.0000   +38.1441 +-   6.2289 el =   8.92 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G16    21.0000    -4.3232 +-   4.5428 el =  67.72 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G18    76.0000    +2.1036 +-   4.5538 el =  57.92 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G23   113.0000   +10.0159 +-   4.5810 el =  48.36 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G26    35.0000    +6.3559 +-   4.5750 el =  49.65 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G27    73.0000    +0.4629 +-   4.5817 el =  48.18 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  G29     0.0000   +49.9988 +-   6.6137 el =   7.69 epo =   35
    2023-06-16_09:38:14.000 AMB  l1  R03   117.0000   +34.3605 +-   6.4598 el =  23.53 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  R04   143.0000   +47.2731 +-   6.4624 el =  23.64 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  R09    -5.0000   +48.7958 +-   6.3264 el =  30.74 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  R11    28.0000   +38.4283 +-   6.4154 el =  25.29 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  R19    47.0000   +16.2556 +-   6.2406 el =  43.32 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  R20   120.0000   +33.7942 +-   6.1980 el =  58.76 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  E08    77.0000   +65.8898 +-   6.9627 el =   7.52 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  E13    81.0000   +33.7635 +-   5.0813 el =  37.34 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  E21    39.0000   +56.5225 +-   5.1852 el =  27.94 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  E26    92.0000   +26.8441 +-   4.9918 el =  85.30 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  E31    49.0000   +33.4906 +-   5.1025 el =  34.94 epo =   36
    2023-06-16_09:38:14.000 AMB  l1  E33   102.0000   +43.9332 +-   5.1225 el =  32.94 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  G07     8.0000   +22.0718 +-   6.7811 el =   8.37 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G08    53.0000   +25.3024 +-   5.6776 el =  14.29 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G10   178.0000   +42.1203 +-   4.9418 el =  28.31 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G15    70.0000   +54.1993 +-   6.5988 el =   8.92 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G16    17.0000    -0.8807 +-   4.5615 el =  67.72 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G18    82.0000    +7.4619 +-   4.5839 el =  57.92 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G23   134.0000   +16.9691 +-   4.6341 el =  48.36 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G26    44.0000   +13.2868 +-   4.6235 el =  49.65 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G27   101.0000    +5.6545 +-   4.6356 el =  48.18 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  G29     1.0000   +68.7951 +-   6.9778 el =   7.69 epo =   35
    2023-06-16_09:38:14.000 AMB  l2  R03   135.0000   +45.1982 +-   6.6031 el =  23.53 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  R04   168.0000   +61.0757 +-   6.6058 el =  23.64 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  R09     0.0000   +63.1095 +-   6.4108 el =  30.74 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  R11    21.0000   +50.5331 +-   6.5436 el =  25.29 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  R19    56.0000   +21.4200 +-   6.2645 el =  43.32 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  R20   131.0000   +43.2465 +-   6.1891 el =  58.76 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  E08    97.0000   +88.7774 +-   7.3052 el =   7.52 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  E13    98.0000   +45.9230 +-   5.1467 el =  37.34 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  E21    50.0000   +76.6428 +-   5.3224 el =  27.94 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  E26   120.0000   +36.6538 +-   4.9688 el =  85.30 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  E31    65.0000   +44.7096 +-   5.1844 el =  34.94 epo =   36
    2023-06-16_09:38:14.000 AMB  l2  E33   129.0000   +59.3032 +-   5.2189 el =  32.94 epo =   36
    2023-06-16_09:38:14.000 WTZR00DEU0 X = 4075580.2827 +- 0.0492 Y = 931854.0960 +- 0.0325 Z = 4801568.3183 +- 0.0616 dN = 0.0042 +- 0.0329 dE = 0.0062 +- 0.0297 dU = 0.0140 +- 0.0728

Depending on selected processing options you find 'GPS Time' stamps (yyyy-mm-dd_hh:mm:ss.sss) followed by

SATNUM G | Number of satellites per contributing GNSS, here GPS
RES ci/li | Code and phase residuals for contributing GNSS in [m] given per satellite
REC_CLK | Receiver clock errors in [m], here GPS
OFF_GAL | Time offset between GNSS time in [m], here between GPS and Galileo
TRP | A priori and correction values of tropospheric zenith delay in [m]
ION | A priori and correction values of ionospheric delay in [m]
AMB li | Floated ambiguities given per satellite with 'nEpo' = number of epochs since last ambiguity reset
MOUNTPOINT | Here 'WTZR00DEU0' with XYZ position in [m] and dN/dE/dU in [m] for North, East, and Up displacements compared to a priori marker coordinates

Estimated parameters are presented together with their formal errors as derived from the implemented filter. The PPP algorithm includes outlier and cycle slip detection.

Default value for 'Logfile directory' is an empty option field, meaning that you do not want to save daily PPP logfiles on disk. If a specified directory does not exist, BNC will not create PPP logfiles.

BNC follows the RINEX Version 3 standard to create filenames for PPP logfiles (suffix 'ppp'), see section 'RINEX Filenames' for details:

      WTZR00DEU_20223220000_01D_01S.ppp

#### 2.13.1.12 NMEA Directory - optional

You can specify a 'NMEA directory' to save daily NMEA files with Point Positioning results recorded as NMEA sentences. Such sentences are usually generated about once per second with pairs of

- GPGGA sentences which mainly carry the estimated latitude, longitude, and height values, plus
- GPRMC sentences which mainly carry date and time information.

The following is an example for an NMEA output file from BNC.

    $GPGGA,214523.00,4908.6520501,N,01252.7348655,E,1,21,0.6,665.993,M,0.0,M,,*56
    $GPRMC,214524.000,A,4908.6521,N,01252.7349,E,,,171122,,*09
    $GPGGA,214524.00,4908.6520504,N,01252.7348645,E,1,21,0.6,665.994,M,0.0,M,,*52
    $GPRMC,214525.000,A,4908.6521,N,01252.7349,E,,,171122,,*08
    $GPGGA,214525.00,4908.6520501,N,01252.7348639,E,1,21,0.6,665.993,M,0.0,M,,*5a
    $GPRMC,214526.000,A,4908.6521,N,01252.7349,E,,,171122,,*0b
    $GPGGA,214526.00,4908.6520509,N,01252.7348637,E,1,21,0.6,665.990,M,0.0,M,,*5c
    $GPRMC,214527.000,A,4908.6521,N,01252.7349,E,,,171122,,*0a
    $GPGGA,214527.00,4908.6520502,N,01252.7348627,E,1,21,0.6,665.990,M,0.0,M,,*57
    $GPRMC,214528.000,A,4908.6520,N,01252.7349,E,,,171122,,*04
    $GPGGA,214528.00,4908.6520499,N,01252.7348630,E,1,21,0.6,665.988,M,0.0,M,,*54
    $GPRMC,214529.000,A,4908.6520,N,01252.7349,E,,,171122,,*05
    $GPGGA,214529.00,4908.6520494,N,01252.7348627,E,1,21,0.6,665.985,M,0.0,M,,*53
    $GPRMC,214530.000,A,4908.6521,N,01252.7349,E,,,171122,,*0c
    $GPGGA,214530.00,4908.6520501,N,01252.7348622,E,1,21,0.6,665.984,M,0.0,M,,*52
    $GPRMC,214531.000,A,4908.6521,N,01252.7349,E,,,171122,,*0d
    $GPGGA,214531.00,4908.6520504,N,01252.7348629,E,1,21,0.6,665.987,M,0.0,M,,*5e
    ...

BNC follows the RINEX Version 3 standard to create filenames for NMEA logfiles (suffix 'nmea'), see section 'RINEX Filenames' for details:

      WTZR00DEU_20223220000_01D_01S.nmea

The default value for 'NMEA directory' is an empty option field, meaning that BNC will not save NMEA sentences into files. If a specified directory does not exist, BNC will not create NMEA files.

Note that Tomoji Takasu has written a program named RTKPLOT for visualizing NMEA sentences from IP ports or files. It is available from http://www.rtklib.com and compatible with the 'NMEA Directory' and port output of BNC's 'PPP' client option.

#### 2.13.1.13 SNX TRO Directory - optional

BNC estimates the tropospheric delay according to equation

       T(z) = T_apr(z) + dT / cos(z)

where T_apr is the a priori tropospheric delay derived from Saastamoinen model.

You can specify a 'SNX TRO Directory' for saving SINEX Troposphere files on disk, see https://files.igs.org/pub/data/format/sinex_tro_v2.00.pdf for a documentation of the file format. Note that receiver type information for these files must be provided through the coordinates file described in section 'Coordinates file'. The following is an example for a troposphere file content:

    %=TRO 2.00 BKG 23:152:00000 BKG 23:152:00000 23:152:03599 P 03600 0  T
    +FILE/REFERENCE
     DESCRIPTION        BNC generated SINEX TRO file
     OUTPUT             Total Troposphere Zenith Path Delay Product
     SOFTWARE           BNC 2.13.0
     INPUT              Observations: WTZR00DEU, SSR corrections: SSRA00BKG1
    -FILE/REFERENCE

    +SITE/ID
    *CODE      PT DOMES____ T _STATION DESCRIPTION__ APPROX_LON_ APPROX_LAT_ _APP_H_
     WTZR00DEU  A           P DEU                     12 52 44.1  49  8 39.1   666.0
    -SITE/ID

    +SITE/RECEIVER
    *SITE      PT SOLN T DATA_START__ DATA_END____ DESCRIPTION_________ S/N__ FIRMWARE___
     WTZR00DEU  A    1 P 23:152:00000 23:152:03599           LEICA GR25 ----- -----------
    -SITE/RECEIVER

    +SITE/ANTENNA
    *SITE      PT SOLN T DATA_START__ DATA_END____ DESCRIPTION_________ S/N__
     WTZR00DEU  A    1 P 23:152:00000 23:152:03599 LEIAR25.R3      LEIT -----
    -SITE/ANTENNA

    +SITE/GPS_PHASE_CENTER
    *                           UP____ NORTH_ EAST__ UP____ NORTH_ EAST__
    *DESCRIPTION_________ S/N__ L1->ARP(m)__________ L2->ARP(m)__________ AZ_EL____
     LEIAR25.R3      LEIT ----- +.1610 -.0001 +.0009 +.1578 -.0004 +.0001 ---------
    -SITE/GPS_PHASE_CENTER

    +SITE/GLONASS_PHASE_CENTER
    *                           UP____ NORTH_ EAST__ UP____ NORTH_ EAST__
    *DESCRIPTION_________ S/N__ L1->ARP(m)__________ L2->ARP(m)__________ AZ_EL____
     LEIAR25.R3      LEIT ----- +.1598 +.0000 +.0009 +.1554 -.0006 -.0002 ---------
    -SITE/GLONASS_PHASE_CENTER

    +SITE/GALILEO_PHASE_CENTER
    *                           UP____ NORTH_ EAST__ UP____ NORTH_ EAST__
    *DESCRIPTION_________ S/N__ L1->ARP(m)__________ L2->ARP(m)__________ AZ_EL____
     LEIAR25.R3      LEIT ----- +.1610 -.0001 +.0009 +.1626 -.0006 -.0001 ---------
    -SITE/GALILEO_PHASE_CENTER

    +SITE/ECCENTRICITY
    *                                             UP______ NORTH___ EAST____
    *SITE      PT SOLN T DATA_START__ DATA_END____ AXE ARP->BENCHMARK(M)_________
     WTZR00DEU  A    1 P 23:152:00000 23:152:03599 UNE   0.0710   0.0000   0.0000
    -SITE/ECCENTRICITY

    +TROP/COORDINATES
    *SITE      PT SOLN T STA_X_______ STA_Y_______ STA_Z_______ SYSTEM REMARK
     WTZR00DEU  A    1 P  4075580.278   931854.089  4801568.305 IGS20 BKG
    -TROP/COORDINATES

    +TROP/DESCRIPTION
    *KEYWORD______________________ VALUE(S)______________
     SAMPLING INTERVAL                                  1
     SAMPLING TROP                                      1
     ELEVATION CUTOFF ANGLE                             7
     OCEAN TIDE LOADING MODEL      BNC.BLQ
     TROP MAPPING FUNCTION         Saastamoinen
     SOLUTION_FIELDS_1             TROTOT STDEV
    -TROP/DESCRIPTION

    +TROP/SOLUTION
    *SITE      EPOCH_______ TROTOT STDEV
     WTZR00DEU 23:152:39051 2183.7 100.0
     WTZR00DEU 23:152:39052 2183.8 100.0
     WTZR00DEU 23:152:39053 2184.1  99.9
     WTZR00DEU 23:152:39054 2184.5  99.9
     WTZR00DEU 23:152:39055 2184.8  99.8
     WTZR00DEU 23:152:39056 2184.9  99.8
     WTZR00DEU 23:152:39057 2185.2  99.7
     WTZR00DEU 23:152:39058 2185.3  99.6
     WTZR00DEU 23:152:39059 2185.7  99.6
     WTZR00DEU 23:152:39060 2186.0  99.5
     WTZR00DEU 23:152:39061 2186.5  99.4
     WTZR00DEU 23:152:39062 2187.6  99.3
     WTZR00DEU 23:152:39063 2188.2  99.1
     WTZR00DEU 23:152:39064 2189.4  99.0
     WTZR00DEU 23:152:39065 2189.7  98.8
     WTZR00DEU 23:152:39066 2190.5  98.6
     WTZR00DEU 23:152:39067 2191.5  98.5
     WTZR00DEU 23:152:39068 2192.0  98.2
     WTZR00DEU 23:152:39069 2193.0  98.0
     WTZR00DEU 23:152:39070 2194.0  97.7
     WTZR00DEU 23:152:39071 2195.0  97.5
     WTZR00DEU 23:152:39072 2195.6  97.2
     WTZR00DEU 23:152:39073 2196.5  96.8
     WTZR00DEU 23:152:39074 2197.7  96.5
    -TROP/SOLUTION
    %=ENDTROP

For file naming, BNC follows the new format convention according to IGS products considering the site http://acc.igs.org/repro3/Long_Product_Filenames_v1.0.pdf:

      AAAVPPPTTT_YYYYDOYHHMM_LEN_SMP_SITENAME_CNT.FMT

With

AAA | Analysis Center abbrevaition
V | Version / Solution identifier (0-9)
PPP | Project/Campaign identification, here demonstration (DEM)
TTT | Solution Type, here real-time streamed product(RTS)
YYYYDOYHHMM | String representing beginning time of nominal data interval
LEN | Intended product period of the file
SMP | Data sampling rate
SITENAME | 9-char site name
CNT | Content type, here TRO
FMT | File format, here TRO

A result for examle is:

      BKG1DEMRTS_20231521000_01H_01S_WTZR00DEU_TRO.TRO

The default value for 'SNX TRO Directory' is an empty option field, meaning that BNC will not save SINEX Troposphere files. If a specified directory does not exist, BNC will not create SINEX Troposphere files.

#### 2.13.1.13.1 Interval - mandatory if 'SINEX TRO Directory' is set

Select the length of SINEX Troposphere files.

Default 'Interval' for saving SINEX Troposphere files on disk is '1 day'.

#### 2.13.1.13.2 Sampling - mandatory if 'SINEX TRO Directory' is set

Select a 'Sampling' rate in seconds for saving troposphere parameters.

Default 'Sampling' rate is '0', meaning that all troposphere estimates will be saved on disk.

#### 2.13.1.13.3 Analysis Center - Mandatory if 'SINEX TRO Directory' is set

Specify a 3-character abbreviation describing you as the generating Analysis Center (AC) in your SINEX troposphere files. String 'BKG' is an example.

#### 2.13.1.13.4 Solution ID - Mandatory if 'SINEX TRO Directory' is set

Specify a 1-character solution ID to allow a distingtion between different solutions per AC. String '1' is an example.

#### 2.13.2 PPP (2): Processing Options

BNC allows using various Point Positioning processing options depending on the capability of the involved receiver and the application in mind. You can introduce specific sigmas for code and phase observations as well as for a priori coordinates and troposphere estimates. You could also carry out your PPP solution in Quick-Start mode or enforce BNC to restart a solution if the length of an outage exceeds a certain threshold.

The intention of this panel is to specify general processing options to be applied to all PPP threads in one BNC job.

Figure 23: Precise Point Positioning with BNC, PPP Panel 2

#### 2.13.2.1 GNSS Observations - mandatory

Specify on which kind of GNSS observations you want to use. The specification is to be done per GNSS system ('GPS', 'GLONASS', 'Galileo', 'BDS').

- Specifying 'Pi' means that you request BNC to use code data of two frequencies.
- Specifying 'Li' means that you request BNC to use phase data of two frequencies.
- Specifying 'Pi&Li' means that you request BNC to use code and phase data of two frequencies.

Note that most geodetic GPS receivers support the observation of both, code and phase data. Hence, specifying 'Pi&Li' would be a good choice for GPS when processing data from such a receiver. If multi-GNSS data processing is your intention, make sure your receiver supports GLONASS and/or Galileo and/or BDS observations besides GPS. Note also that the Broadcast Correction stream or file, which is required for PPP, also supports all the systems you have in mind.

Specifying 'no' means that you do not at all want BNC to use observations from the affected GNSS system.

#### 2.13.2.2 Code Observations - mandatory

Enter a 'Sigma C1' for C1 code observations in meters. The bigger the sigma you enter, the less the contribution of C1 code observations to a PPP solution based on a combination of code and phase data. '2.0' meters is likely to be an appropriate choice.

Specify a maximum for residuals 'Max Res C1' for C1 code observations in a PPP solution. '3.0' meters may be an appropriate choice for that. If the maximum is exceeded, contributions from the corresponding observation will be ignored in the PPP solution.

#### 2.13.2.3 Phase Observations - mandatory

Enter a 'Sigma L1' for L1 phase observations in meters. The bigger the sigma you enter, the less the contribution of L1 phase observations to a PPP solutions based on a combination of code and phase data. '0.01' meters is likely to be an appropriate choice.

Specify a maximum for residuals 'Max Res L1' for L1 phase observations in a PPP solution. '0.03' meters may be an appropriate choice for that. If the maximum is exceeded, contributions from the corresponding observation will be ignored in the PPP solution.

As the convergence characteristic of a PPP solution can be influenced by the ratio of sigmas for code and phase, you may like to introduce sigmas which differ from the default values.

- Introducing a smaller sigma (higher accuracy) for code observations or a bigger sigma for phase observations leads to better results shortly after program start. However, it may take more time until you finally get the best possible solution.
- Introducing a bigger sigma (lower accuracy) for code observations or a smaller sigma for phase observations may lead to less accurate results shortly after program start and thus a prolonged period of convergence but could provide better positions in the long run.

#### 2.13.2.4 Elevation Dependent Weighting - mandatory

BNC allows elevation dependent weighting when processing GNSS observations. A weight function

P = cos² * z

with 'z' being the zenith distance to the involved satellite can be applied instead of the simple weight function 'P = 1' independent from satellite elevation angles.

- Tick 'Ele Wgt Code' if you want Elevation Dependent Weighting for code observations.
- Tick 'Ele Wgt Phase' if you want Elevation Dependent Weighting for phase observations.

Default is using the plain weight function 'P = 1' for code and phase observations.

#### 2.13.2.5 Minimum Number of Observations - mandatory

Select the minimum number of observations you want to use per epoch. The minimum for parameter 'Min # of Obs' is 5. This is also the default.

#### 2.13.2.6 Minimum Elevation - mandatory

Select a minimum for satellite elevation angles. Selecting '7 deg' for option 'Min Elevation' may be an appropriate choice.

Default is '0 deg', meaning that any observation will be used regardless of the involved satellite elevation angle.

#### 2.13.2.7 Wait for Clock Corrections - optional

Specifying 'no' for option 'Wait for clock corr.' means that BNC processes each epoch of data immediately after its arrival using satellite clock corrections available at that time. A non-zero value means that epochs of data are buffered and the processing of each epoch is postponed until satellite clock corrections not older than 'Wait for clock corr.' seconds are available. Specifying a value of half the update rate of the clock corrections (e.g. 5 sec) may be appropriate. Note that this causes an additional delay of the PPP solutions in the amount of half of the update rate.

Using observations in sync with the corrections can avoid a possible high frequency noise of PPP solutions. Such noise could result from processing observations regardless of how late after a clock correction they were received. Note that applying the 'Wait for clock corr.' option significantly reduces the PPP computation effort for BNC.

Default is an empty option field, meaning that you want BNC to process observations immediately after their arrival through applying the latest received clock correction.

#### 2.13.2.8 Seeding - optional if a priori coordinates specified in 'Coordinates file'

Enter the length of a startup period in seconds for which you want to fix the PPP solution to a known position, see option 'Coordinates file'. Constraining a priori coordinates is done in BNC through setting their white 'Noise' temporarily to zero.

This so-called Quick-Start option allows the PPP solutions to rapidly converge after startup. It requires that the antenna remains unmoved on the known position throughout the defined period. A value of '60' seconds is likely to be an appropriate choice for 'Seeding'. Default is an empty option field, meaning that you do not want BNC to start in Quick-Start mode.

You may need to create your own reference coordinate beforehand through running BNC for an hour in normal mode before applying the 'Seeding' option. Do not forget to introduce realistic North/East/Up sigmas under panel 'PPP (3)' corresponding to the coordinate's precision.

'Seeding' has also a function for bridging gaps in PPP solutions from failures caused e.g. by longer lasting outages. Should the time span between two consecutive solutions exceed the limit of 60 seconds (maximum solution gap, hard-wired), the algorithm fixes the latest derived coordinate for a period of 'Seeding' seconds. This option avoids time-consuming reconvergences and makes especially sense for stationary operated receivers where convergence can be enforced because a good approximation for the receiver position is known.

#### 2.13.2.9 Pseudo Observations - optional

Specify whether pseudo observations regarding the Ionosphere shall be used. Please note, this is useful, as soon as the ionospheric information is more accurate than the code data accuracy.

#### 2.13.2.10 GIM Pseudo Observations - optional

Enter a 'Sigma GIM' for pseudo observations regarding the Ionosphere in meters. The bigger the sigma you enter, the less the contribution of GIM Pseudo observations to a PPP solutions based on a combination of code and phase data. '5.0' meters is likely to be an appropriate choice.

Specify a maximum for residuals 'Max Res GIM' for pseudo observations regarding the Ionosphere in a PPP solution. '3.0' meters may be an appropriate choice for that. If the maximum is exceeded, contributions from the corresponding observation will be ignored in the PPP solution.

The following figure provides the screenshot of an example PPP session with BNC.

Figure 24: Precise Point Positioning with BNC in 'Quick-Start' mode, PPP Panel 4

#### 2.13.3 PPP (3): Processed Stations

This panel allows to enter parameters specific to each PPP process or thread. Individual sigmas for a priori coordinates and a noise for coordinate variations over time can be introduced. Furthermore, a sigma for model-based troposphere estimates and the corresponding noise for troposphere variations can be specified. Finally, local IP server ports can be defined for output of NMEA streams carrying PPP results.

BNC offers to create a table with one line per PPP process or thread to specify station-specific parameters. Hit the 'Add Station' button to create the table or add a new line to it. To remove a line from the table, highlight it by clicking it and hit the 'Delete Station' button. You can also remove multiple lines simultaneously by highlighting them using +Shift or +Ctrl.

BNC will simultaneously produce PPP solutions for all stations listed in the 'Station' column of this table.

Figure 25: Precise Point Positioning with BNC, PPP Panel 3

#### 2.13.2.1 Station - mandatory

Hit the 'Add Station' button, double click on the 'Station' field, then specify an observation's mountpoint from the 'Streams' section or introduce the 9-character Station ID of your RINEX observation file and hit Enter. BNC will only produce PPP solutions for stations listed in this table.

#### 2.13.2.2 Sigma North/East/Up - mandatory

Enter sigmas in meters for the initial coordinate components. A value of 100.0 (default) may be an appropriate choice. However, this value may be significantly smaller (e.g. 0.01) when starting for example from a station with a well-known position in so-called Quick-Start mode.

#### 2.13.2.3 Noise North/East/Up - mandatory

Enter a white 'Noise' in meters for estimated coordinate components. A value of 100.0 (default) may be appropriate when considering possible sudden movements of a rover.

#### 2.13.2.4 Tropo Sigma - mandatory

Enter a sigma in meters for the a priori model based tropospheric delay estimation. A value of 0.1 (default) may be an appropriate choice.

#### 2.13.2.5 Tropo Noise - mandatory

Enter a white 'Noise' in meters per second to describe the expected variation of the tropospheric effect. Supposing 1Hz observation data, a value of 3e-6 (default) would mean that the tropospheric effect may vary for 3600 * 3e-6 = 0.01 meters per hour.

#### 2.13.2.6 NMEA Port - optional

Specify the IP port number of a local port where Point Positioning results become available as NMEA sentences. The default value for 'NMEA Port' is an empty option field, meaning that BNC does not provide NMEA sentences via IP port. Note that NMEA file output and NMEA IP port output are the same.

Note also that Tomoji Takasu has written a program named RTKPLOT for visualizing NMEA sentences from IP ports or files. It is available from http://www.rtklib.com and compatible with the NMEA file and port output of BNC's 'PPP' client option.

Furthermore, NASA's 'World Wind' software (see http://worldwindcentral.com/wiki/NASA_World_Wind_Download) can be used for real-time visualization of positions provided through BNC's NMEA IP output port. You need the 'GPS Tracker' plug-in available from http://worldwindcentral.com/wiki/GPS_Tracker for that. The 'Word Wind' map resolution is not meant for showing centimeter level details.

#### 2.13.2.7 Signal Priorities - optional

Specify a list of signal priorities (2 frequencies per system) for the observations that shall be used for PPP.

'Signal Priorities' can be specified as equal for all systems, as system specific or as system and frequency specific. For example:

- 'CWPX_?' (General signal priorities valid for all GNSS)
- 'E:IQX' (System specific signal priorities for Galileo)
- 'G:12&PWCSLX G:5&IQX R:12&PC R:3&IQX' (System and frequency specific signal priorities)

Default for all PPP models is the following list of 'Signal Priorities':

- 'G:12&CWPSLX R:12&CP E:1&CBX E:5&QIX C:26&IQX'

But it is recommended to specify it in more detail per individual station, e.g.:

- 'G:12&W R:12&P E:1&C E:5&Q C:26&I'

#### 2.13.4 PPP (4): Plots

This panel presents options for visualizing PPP results as a time series plot or as a track map with PPP tracks on top of OpenStreetMap (OSM) maps.

#### 2.13.4.1 PPP Plot - optional

PPP time series of North (red), East (green) and Up (blue) displacements will be plotted under the 'PPP Plot' tab when a 'Mountpoint' is specified. Values will be referred to an XYZ reference coordinate (if specified, see 'Coordinates file'). The sliding PPP time series window will cover the period of the latest 5 minutes.

Note that a PPP dicplacements time series makes only sense for a stationary operated receiver.

#### 2.13.4.2 Audio Response - optional

For natural hazard prediction and monitoring landslides, it may be appropriate to generate audio alerts. For that you can specify an 'Audio response' threshold in meters. A beep is produced by BNC whenever a horizontal PPP coordinate component differs by more than the threshold value from the specified marker coordinate.

Default is an empty option field, meaning that you do not want BNC to produce acoustic warnings.

#### 2.13.4.3 Track Map - optional

You may like to track your rover position using OpenStreetMap as a background map. Track maps can be produced with BNC in 'Real-time Streams' mode or in 'RINEX Files' post processing mode with data coming from files. Even when in 'RINEX Files' post processing mode, you should not forget to go online with your host.

The 'Open Map' button opens a window showing the map.

Figure 26: Track of positions from BNC with OpenStreetMap in background

#### 2.13.4.4 Dot-properties - mandatory before pushing 'Open Map'

PPP tracks are presented on maps through plotting one colored dot per observation epoch.

#### 2.13.4.4.1 Size - mandatory before pushing 'Open Map'

Specify the size of dots showing the rover position. A dot size of '3' may be appropriate. The maximum possible dot size is '10'. An empty option field or a size of '0' would mean that you do not want BNC to show the rover's track on the map.

#### 2.13.4.4.2 Color - mandatory before pushing 'Open Map'

Select the color of dots showing the rover track.

#### 2.13.4.5 Post Processing Speed - mandatory before pushing 'Open Map'

With BNC in PPP 'RINEX File' post processing mode, you can specify the speed of computations as appropriate for visualization. Note that you can adjust 'Post-processing speed' on-the-fly while BNC is already processing your observations.

#### 2.14 Combine Corrections

BNC allows processing several orbit and clock correction streams in real-time to produce, encode, upload and save a combination of Broadcast Corrections from various providers (Weber and Mervart 2010). All corrections must refer to satellite Antenna Phase Centers (APC). It is so far only the satellite clock corrections, which are combined by BNC while orbit corrections in the combination product are just taken over from one of the incoming Broadcast Correction streams. Combining only clock corrections using a fixed orbit reference imposes the potential to introduce some analysis inconsistencies. We will therefore consider improvements on this approach.

The 'Combine Corrections' functionality may be of interrest because:

- Outages of single AC product streams can be mitigated through merging several incoming streams into a combined product;
- Generating a combination product from several AC products allows detecting and rejecting outliers;
- A Combination Center (CC) can operate BNC to globally disseminate a combination product via Ntrip broadcast;
- An individual AC could prefer to disseminate a stream combined from primary and backup IT resources to reduce outages;
- It enables a BNC PPP user to follow his own preference in combining streams from individual ACs for Precise Point Positioning;
- It allows an instantaneous quality control of the combination process not only in the time domain but also in the space domain; this can be done by direct application of the combined stream in a PPP solution even without prior upload to an Ntrip Broadcaster;
- It provides the means to output SP3 and Clock RINEX files containing precise orbit and clock information as well as SINEX Bias files for further processing using other tools than BNC.

The clock combination can be based either on a plain 'Single-Epoch' or on a 'Kalman Filter' approach. In the 'Kalman Filter' approach, satellite clocks estimated by individual Analyses Centers (ACs) are used as pseudo observations within the adjustment process. Each observation is modeled as a linear function (actually a simple sum) of three estimated parameters:

     Clk_Corr = AC_Offset + Sat_Offset + Clk

With

AC_Offset | AC specific offset
Sat_Offset | Satellite specific offset common to all ACs
Clk | the actual satellite clock correction, which represents the result of the combination

These three parameter types differ in their statistical properties. The satellite clock offsets are assumed to be static parameters while AC specific and satellite specific offsets are stochastic parameters affected by white noise. The solution is regularized by a set of minimal constraints. In case of a change of the 'SSR Provider ID', 'SSR Solution ID', or 'IOD SSR' (see section 'Upload Corrections'), the satellite clock offsets belonging to the corresponding analysis center are reset in the adjustment.

Removing the AC-dependent biases as well as possible is a major issue with clock combinations. Since they vary in time, it can be tricky to do this. Otherwise, there will be artificial jumps in the combined clock stream if one or more AC contributions drop out for certain epochs. Here the 'Kalman Filter' approach is expected to do better than the 'Single-Epoch' approach.

The following recursive algorithm is used to detect orbit outliers in the Kalman Filter combination when Broadcast Corrections are provided by several ACs:

Step 1 | We do not produce a combination for a certain satellite if only one AC provides corrections for it.
Step 2 | A mean satellite position is calculated as the average of positions from all ACs.
Step 3 | For each AC and satellite, the 3D distance between individual and mean satellite position is calculated.
Step 4 | We find the greatest difference between AC specific and mean satellite positions.
Step 5 | If that is less than a threshold, the conclusion is that we do not have an outlier and can proceed to the next epoch.
Step 6 | If that is greater than a threshold, then corrections of the affiliated AC are ignored for the affected epoch and the outlier detection restarts with step 1.

The following screenshot shows an example setup of BNC when combining Broadcast Correction streams SSRA00BKG1 and SSRA00CNE1.

Figure 27: BNC combining Broadcast Correction streams

The combination process requires real-time access to Broadcast Ephemeris. Therefore, in addition to the orbit and clock correction streams BNC must pull a stream carrying Broadcast Ephemeris in the form of RTCM Version 3 messages. Stream 'BCEP00BKG0' on caster http://products.igs-ip.net is an example for that. Note further that BNC will ignore incorrect or outdated Broadcast Ephemeris data when necessary, leaving a note 'WRONG EPHEMERIS' or 'OUTDATED EPHEMERIS' in the logfile.

The combination is done system-wise for the following reference signals as specified in the IGS RTWG:

GPS: | C1W/C2W
GLONASS: | C1P/C2P
Galileo: | C1C/C5Q
BDS: | C2I/C6I
QZSS: | C1C/C2L
SBAS: | C1C/C5Q
IRNSS: | nothing declared

Assuming that the ACs generate ionosphere-free clocks based on their individual choosen signals, the ionosphere-free code biases for the reference signals as specified in the IGS RTWG are determined from the supplied code biases. These are subtracted from each of the clocks before combination, resulting in combined code-bias-free and ionosphere-free clocks.

This can be used to set the ionosphere-free linearcombination of two Observable-specific Signal Biases (OSBs; those of the reference signals) to zero in order to calculate all other OSBs. For this, we use currently the satellite biases which are computed by the Institute of Geodesy and Geophysics (IGG) of the Chinese Academy of Sciences (CAS) and send them out as SSR code biases together with the combined clocks. These SINEX Bias files are archived at the CDDIS: https://cddis.nasa.gov/archive/gnss/products/bias/

A combination is carried out following a specified sampling interval. BNC waits for incoming Broadcast Corrections for the period of one such interval. Corrections received later than that will be ignored. If incoming streams have different rates, only epochs that correspond to the sampling interval are used.

Note that BNC can produce an internal PPP solution from combined Broadcast Corrections. For that you have to specify the keyword 'INTERNAL' as 'Corrections stream' in the PPP (1) panel. The following example combines correction streams SSRA00BKG1 and SSRA00CNE1 and simultaneously carries out a PPP solution with observations from stream FFMJ01DEU0 to allow monitoring the quality of the combination product in the space domain.

Figure 28: 'INTERNAL' PPP with BNC using a combination of Broadcast Corrections

#### 2.14.1 Combine Corrections Table - optional

Hit the 'Add Row' button, double click on the 'Mountpoint' field, enter a Broadcast Correction mountpoint from the 'Streams' section and hit Enter. Then double click on the 'AC Name' field to enter your choice of an abbreviation for the Analysis Center (AC) providing the Antenna Phase Center (APC) related correction stream. Finally, double click on the 'Weight' field to enter a weight to be applied to this stream in the combination.

The sequence of entries in the 'Combine Corrections' table is not of importance. Note that the orbit information in the final combination stream is just copied from one of the incoming streams. The stream used for providing the orbits may vary over time: if the orbit-providing stream has an outage then BNC switches to the next remaining stream for getting hold of the orbit information.

It is possible to specify only one Broadcast Ephemeris correction stream in the 'Combine Corrections' table. Instead of combining corrections from several sources, BNC will then merge the single corrections stream with Broadcast Ephemeris to allow saving results in SP3 and/or Clock RINEX format when specified accordingly under the 'Upload Corrections' panel. Note that in such a BNC application you must not pull more than one Broadcast Ephemeris correction stream even if a second stream would provide the same corrections from a backup caster.

Default is an empty 'Combine Corrections' table, meaning that you do not want BNC to combine orbit and clock correction streams.

#### 2.14.1.1 Add Row, Delete - optional

Hit 'Add Row' button to add another row to the 'Combine Corrections' table or hit the 'Delete' button to delete the highlighted row(s).

#### 2.14.1.2 Method - mandatory if 'Combine Corrections' table is populated

Select a clock combination method. Available options are 'Kalman Filter' and 'Single-Epoch'. It is suggested to use the 'Kalman Filter' approach in case the combined stream of Broadcast Corrections is intended for Precise Point Positioning.

#### 2.14.1.3 Maximal Residuum - mandatory if 'Combine Corrections' table is populated

BNC combines all incoming clocks according to specified weights. Individual clock estimates that differ by more than 'Maximal Residuum' meters from the average of all clocks will be ignored. It is suggested to specify a value of about 0.2 m for the Kalman Filter combination approach and a value of about 3.0 meters for the Single-Epoch combination approach.

Default is a 'Maximal Residuum' of 999.0 meters.

#### 2.14.1.4 Sampling - mandatory if 'Combine Corrections' table is populated

Specify a combination sampling interval. Orbit and clock corrections will be produced following that interval. value of 10 sec may be an appropriate choice.

#### 2.15 Upload Corrections

BNC can upload streams carrying orbit and clock corrections to Broadcast Ephemeris in radial, along-track and out-of-plane components if they are

1. either generated by BNC as a combination of several individual Broadcast Correction streams coming from an number of real-time Analysis Centers (ACs), see section 'Combine Corrections',
2. or generated by BNC while the program receives an ASCII stream of precise satellite orbits and clocks via IP port from a connected real-time GNSS engine. Such a stream would be expected in a plain ASCII format and the associated 'decoder' string would have to be 'RTNET', see format description below.

The procedure taken by BNC to generate the orbit and clock corrections to Broadcast Ephemeris and upload them to an Ntrip Broadcaster is as follow:

- Continuously receive up-to-date Broadcast Ephemeris carrying approximate orbits and clocks for all satellites. Read new Broadcast Ephemeris immediately whenever they become available. This information may come via a stream of RTCM messages generated from another BNC instance.

Then, epoch by epoch:

- Continuously receive the best available orbit and clock estimates for all satellites in XYZ Earth-Centered-Earth-Fixed IGS20 reference system. Receive them every epoch in plain ASCII format as provided by a real-time GNSS engine such as RTNET or generate them following a combination approach.
- Calculate XYZ coordinates from Broadcast Ephemeris orbits.
- Calculate differences dX,dY,dZ between Broadcast Ephemeris and IGS20 orbits.
- Transform these differences into radial, along-track and out-of-plane corrections to Broadcast Ephemeris orbits.
- Calculate corrections to Broadcast Ephemeris clocks as differences between Broadcast Ephemeris clocks and IGS20 clocks.
- Encode Broadcast Ephemeris orbit and clock corrections, biases and atmospheric parameters in 'State Space Reperesentation' messages'
- Upload Broadcast Correction stream to Ntrip Broadcaster.

The orbit and clock corrections to Broadcast Ephemeris are usually referred to the latest set of broadcast messages, which are generally also received in real-time by a GNSS rover. However, the use of the latest broadcast message is delayed for a period of 60 seconds, measured from the time of complete reception of ephemeris and clock parameters, in order to accommodate rover applications to obtain the same set of broadcast orbital and clock parameters. This procedure is recommended in the RTCM SSR standard.

Because the stream delivery process may put a significant load on the communication link between BNC and the real-time GNSS engine, it is recommended to run both programs on the same host. However, doing so is not compulsory.

The usual handling of BNC when uploading a stream with Broadcast Corrections is that you first specify Broadcast Ephemeris and Broadcast Correction streams. You then specify an Ntrip Broadcaster for stream upload before you start the program.

'RTNET' Stream Format: When uploading an SSR stream generated according to (b) then BNC requires precise GNSS orbits and clocks in the IGS Earth-Centered-Earth-Fixed (ECEF) reference system and in a specific ASCII format named 'RTNET' because the data may come from a real-time engine such as RTNET. The sampling interval for data transmission should not exceed 15 sec. Note that otherwise tools involved in IP streaming such as Ntrip Broadcasters or Ntrip Clients may respond with a timeout.

Below you find an example for the 'RTNET' ASCII format coming from a real-time GNSS engine. Each epoch begins with an asterisk character followed by the time as year, month, day of month, hour, minute and second. Subsequent records can provide

- Satellite specific parameters

A set of parameters can be defined for each satellite as follows:

    <SatelliteID> <key> <numValues> <value1 value2 ...>
                  <key> <numValues> <value1 value2 ...> ...

The following satellite specific keys and values are currently specified for that in BNC:

Key | Values
APC | Satellite Antenna Phase Center coordinate components in meters
Clk | Satellite clock correction components in meters, meters per seconds and meters per sec² (relativistic correction applied like in broadcast clocks)
ClkSig | Standard deviation for satellite clock correction components in meters, meters per seconds and meters per sec² (required for Clock RINEX file only) /td>
Vel | Satellite velocity components in meters per second
CoM | Satellite Center of Mass coordinate components in meters
Ura | User range accuracy value in meters
CodeBias | Satellite Code Biases in meters with two characters for frequency and tracking mode per bias as defined in RINEX 3/4 and preceded by total number of biases
PhaseBias | Satellite Phase Biases in meters with two characters for frequency and tracking mode per bias as defined in RINEX 3/4, preceded by total number of biases and followed by Signal Integer Indicator, Signals Wilde-Lane Integer Indicator as well as Signal Discontinuity Counter
YawAngle | Satellite Yaw Angle in radian, restricted to be in [0, 2π], which shall be used for the computation of phase wind-up correction
YawRate | Satellite Yaw Rate in radian per second which is the rate of Yaw Angle

- Non-satellite specific parameters

The following syntax will be used:

    <key> <value1 value2 ...>

The following non-satellite specific keys and values are currently specified in BNC:

Key | Values
IND | Stands for phase bias information and is followed by Dispersive Bias Consistency Indicator and MW Consistency Indicator
VTEC | Stands for Vertical TEC information and is followed by Update Interval and Number of Ionospheric Layers

If key VTEC is specified, a data set for each layer contains within its first line the Layers Number, followed by Maximum Degree, Maximum Order and Layer Height. After that, Cosine and Sinus Spherical Harmonic Coefficients will follow, one block each.

Because each keyword is associated to a certain number of values, an 'old' BNC could be operated with an incoming 'new' RTNET stream containing so far unknown keys - they would just be skipped in BNC.

Example for 'RTNET' stream content and format:

    *  2022 11 25 22 04 05.000
    G01 Clk 2     73898.6410 -0.00164097340 ClkSig 2   0.0024  0.00021199856 CoM 3  -3022799.7396 -14423300.4562 -22402573.0244 Vel 3   2691.3388   -619.5739     69.3300 APC 3  -3022799.9547 -14423299.6874 -22402571.6928 YawAngle 1 -2.756 CodeBias 3 1C   -2.6653 1W   -3.0640 2W   -5.0462
    G02 Clk 2   -190714.4788  0.00054568041 ClkSig 2   0.0021  0.00021199856 CoM 3   6435781.3836  14022665.7384  22245045.6986 Vel 3  -2523.5253    881.5723    199.4389 APC 3   6435781.2094  14022665.3599  22245045.1006 YawAngle 1 -0.496 CodeBias 3 1C    3.1444 1W    3.6734 2W    6.0498
    G03 Clk 2   -112198.0483 -0.00041212052 ClkSig 2   0.0021  0.00021199856 CoM 3  -9558560.1056 -21678640.8679 -12237759.6868 Vel 3   1195.6635    968.3425  -2665.8087 APC 3  -9558559.9115 -21678639.4511 -12237758.9694 YawAngle 1  2.269 CodeBias 3 1C   -1.9487 1W   -2.1477 2W   -3.5372
    G04 Clk 2    -23967.3447  0.00204827783 ClkSig 2   0.0016  0.00021199854 CoM 3   -925894.8383 -23797191.6947  11651418.9683 Vel 3    684.2944  -1338.1342  -2689.1911 APC 3   -925894.7893 -23797190.5964  11651418.4111 YawAngle 1  1.705 CodeBias 3 1C   -0.1054 1W   -0.2081 2W   -0.3427
    ..
    R01 Clk 2      5546.7099  0.00018335589 ClkSig 2   0.0023  0.00021199856 CoM 3   7112494.0294  23814532.0433  -5735875.7206 Vel 3    284.0303    745.9382   3452.4470 APC 3   7112493.8323  23814529.8302  -5735874.8944 YawAngle 1  1.728 CodeBias 4 1C   -2.6149 1P   -2.7107 2C   -3.6969 2P   -4.4809
    R02 Clk 2     -7008.2454 -0.00000635271 ClkSig 2   0.0023  0.00021199856 CoM 3  11244225.8582  10071470.3245 -20546784.7044 Vel 3    494.7088   2778.4611   1623.0780 APC 3  11244225.2057  10071469.5457 -20546782.4482 YawAngle 1  2.071 CodeBias 4 1C   -0.1018 1P   -0.3894 2C   -0.6264 2P   -0.6436
    R03 Clk 2     20366.1568  0.00020195972 ClkSig 2   0.0021  0.00021199856 CoM 3   9092586.5727  -9144390.0351 -21957806.0158 Vel 3    417.8656   2989.9043  -1076.1050 APC 3   9092586.1678  -9144388.9369 -21957803.7216 YawAngle 1  2.112 CodeBias 4 1C    0.5948 1P    0.9738 2C    1.2086 2P    1.6097
    R04 Clk 2     49846.8890  0.00042529794 ClkSig 2   0.0022  0.00021199856 CoM 3   1867488.4178 -22822850.6299 -11196789.3037 Vel 3     66.4046   1545.5179  -3134.6080 APC 3   1867488.7750 -22822848.4388 -11196788.1327 YawAngle 1  1.866 CodeBias 4 1C    1.0137 1P    1.2486 2C    1.6395 2P    2.0640
    ...
    E02 Clk 2      1444.2848  0.00069346607 ClkSig 2   0.0021  0.00021199856 CoM 3  -3377663.9278  18136033.0351 -23153818.3345 Vel 3  -1715.0309  -1566.2097   -974.6114 APC 3  -3377663.9510  18136032.5368 -23153817.7931 YawAngle 1 -0.010 CodeBias 5 1C    0.2681 1X    0.2629 5I    0.4302 5Q    0.4807 5X    0.4826
    E03 Clk 2   -186952.1234 -0.00113736360 ClkSig 2   0.0024  0.00021199856 CoM 3  -8254601.5653  28187191.4778   3641206.5123 Vel 3    114.7319   -350.5678   2966.0175 APC 3  -8254601.4684  28187190.7479   3641206.3909 YawAngle 1  1.300 CodeBias 5 1C   -0.9944 1X   -0.9846 5I   -1.7540 5Q   -1.7833 5X   -1.7956
    E05 Clk 2    -36305.4464  0.00110429712 ClkSig 2   0.0027  0.00021199857 CoM 3 -16951710.6073  14279857.1039  19615600.3991 Vel 3    411.8010  -1924.3142   1755.9024 APC 3 -16951710.2715  14279856.6791  19615599.8561 YawAngle 1  1.240 CodeBias 5 1C   -1.1095 1X   -1.0961 5I   -1.9636 5Q   -1.9896 5X   -1.9628
    E07 Clk 2      -664.2128 -0.00092754332 ClkSig 2   0.0025  0.00021199857 CoM 3  15638354.9447   7729299.3932 -23916035.7246 Vel 3   -463.7761   2352.3603    457.3356 APC 3  15638354.4877   7729299.1793 -23916035.2351 YawAngle 1  1.776 CodeBias 5 1C   -1.6081 1X   -1.5745 5I   -2.8718 5Q   -2.8838 5X   -2.8389
    ..EOE

Note that the end of an epoch in the incoming stream is indicated by an ASCII string 'EOE' (for End Of Epoch).

The following screenshot shows the encoding and uploading of several streams using precise orbits and clocks coming from a real-time network engine in 'RTNET' ASCII format. The streams are uploaded to Ntrip Broadcaster 'products.igs-ip.net'. They are referred to APC or CoM and IGS20 or DREF91. Required Broadcast Ephemeris are received via stream 'BCEP00BKG0'.

Figure 29: BNC producing Broadcast Corrections from incoming precise orbits and clocks and uploading them to an Ntrip Broadcaster

#### 2.15.1 Add, Delete Row - optional

Hit 'Add Row' button to add a row to the stream 'Upload Table' or hit the 'Delete' button to delete the highlighted row(s). Having an empty 'Upload Table' is default and means that you do not want BNC to upload orbit and clock correction streams to any Ntrip Broadcaster.

#### 2.15.2 Host, Port, Mountpoint, Ntrip Version, User and Password - optional

Specify the domain name or IP number of an Ntrip Broadcaster for uploading the stream. Furthermore, specify the caster's listening IP port and an upload mountpoint. Select the Ntrip Version that shall be used for data upload and, depending on this, an upload user (Ntrip Version 2 only) and an upload password.

Note that Ntrip Broadcasters are often configured to provide access through more than one port, usually ports 80 and 2101. If you experience communication problems on port 80, you should try to use the alternative port(s).

BNC uploads a stream to the Ntrip Broadcaster by referring to a dedicated mountpoint that has been set by its operator. Specify the mountpoint based on the details you received for your stream from the operator. It is often a 9-character ID (capital letters) plus an integer number.

For stream upload the Ntrip Version can be chosen. An Ntrip version 1 upload is protected through an upload 'Password' only. For an Ntrip Version 2 upload an upload 'User' is required in addition. Enter user and password you received from the Ntrip Broadcaster operator along with the mountpoint(s).

If 'Host', 'Port', 'Mountpoint', 'Ntrip' Version, 'User' and 'Password' are set, the stream will be encoded into 'State Space Representation' (SSR) messages and uploaded to the specified broadcaster following the specified Ntrip transport protocol options.

#### 2.15.3 System - mandatory if 'Host' is set

BNC allows configuring several Broadcast Correction streams for upload, so that they may refer to different reference systems and different Ntrip Broadcasters. You may use this functionality for parallel support of a backup Ntrip Broadcaster or for simultaneous support of various regional reference systems. Available options for transforming orbit and clock corrections to specific target reference systems are

IGS20: | Stands for the GNSS-based IGS realization of the International Terrestrial Reference Frame 2020 (ITRF2020)
ETRF2000: | Stands for the European Terrestrial Reference Frame 2000 adopted by EUREF
GDA2020: | Stands for the Geodetic Datum Australia 2020 as adopted for Australia
SIRGAS2000: | Stands for the Geodetic Datum adopted for Brazil
DREF91: | Stands for the Geodetic Datum adopted for Germany
Custom: | Allows a transformation of Broadcast Corrections from the IGS20 system to any other system through specifying up to 14 Helmert Transformation Parameters

Because a mathematically strict transformation to a regional reference system is not possible on the BNC server side when a scale factor is involved, the program follows an approximate solution. While orbits are transformed in full accordance with given equations, a transformed clock is derived through applying correction term

       dC = (s - 1) / s * ρ / c

where s is the transformation scale, c is the speed of light, and ρ are the topocentric distance between an (approximate) center of the transformation's validity area and the satellite.

From a theoretical point of view, this kind of approximation leads to inconsistencies between orbits and clocks and is therefore not allowed (Huisman et al. 2012). However, it has been proved that resulting errors in Precise Point Positioning are on millimeter level for horizontal components and below one centimeter for height components.

IGS20: As the orbits and clocks coming from real-time GNSS engine are expected to be in the IGS20 system, no transformation is carried out if this option is selected.

As long as no updated transformation parameters are available regarding IGS20, a transformation from 'ITRF2020->ITRF2014' is done in a fist step using the following 14 Helmert Transformation Parameters, which are available at https://itrf.ign.fr/en/solutions/transformations

       dx  = -0.0014;
       dy  = -0.0009;
       dz  =  0.0014;

       dxr =  0.0000;
       dyr = -0.0001;
       dzr = -0.0002;

       ox  =  0.0;
       oy  =  0.0;
       oz  =  0.0;

       oxr =  0.0;
       oyr =  0.0;
       ozr =  0.0;

       sc  = -0.4200;
       scr =  0.0;

       t0  =  2015.0;

where

       dx     Translation in X at epoch t0 [m]
       dy     Translation in Y at epoch t0 [m]
       dz     Translation in Z at epoch t0 [m]
       dxr    Translation rate in X at epoch t0 [m/y]
       dyr    Translation rate in Y at epoch t0 [m/y]
       dzr    Translation rate in Z at epoch t0 [m/y]
       oxr    Rotation in X at epoch t0 [mas]
       oyr    Rotation in Y at epoch t0 [mas]
       ozr    Rotation in Z at epoch t0 [mas]
       sc     Scale at epoch t0 [1e-9]
       scr    Scale at epoch t0 [1e-9/y]
       t0     Reference Epoch [y]

ETRF2000: The transformation Parameters from ITRF2014 to ETRF2000 are taken from the EUREF Technical Note 1 'EUREF Technical Note 1: Relationship and Transformation between the International and the European Terrestrial Reference Systems', Zuheir Altamimi, June 28, 2018: http://etrs89.ensg.ign.fr/pub/EUREF-TN-1.pdf:

        dx  =  0.0547;
        dy  =  0.0522;
        dz  = -0.0741;

        dxr =  0.0001;
        dyr =  0.0001;
        dzr = -0.0019;

        ox  =  0.001701;
        oy  =  0.010290;
        oz  = -0.016632;

        oxr =  0.000081;
        oyr =  0.000490;
        ozr = -0.000729;

        sc  =  2.12;
        scr =  0.11;

        t0  =  2010.0;

GDA2020: The parameters for the transformation 'ITRF2014->GDA2020' were provided by Ryan Ruddick (Geoscience Australia): via personal communication:

        dx  = 0.0;
        dy  = 0.0;
        dz  = 0.0;

        dxr = 0.0;
        dyr = 0.0;
        dzr = 0.0;

        ox  = 0.0;
        oy  = 0.0;
        oz  = 0.0;

        oxr = 0.00150379;
        oyr = 0.00118346;
        ozr = 0.00120716;

        sc  = 0.0;
        scr = 0.0;

        t0  = 2020.0;

SIRGAS2000: The parameters for the transformation 'IGb14->SIRGAS2000' were provided from Sonia Costa, BRA via personal communication:.

        dx  = -0.0027;
        dy  = -0.0025;
        dz  = -0.0042;

        dxr =  0.0;
        dyr =  0.0;
        dzr =  0.0;

        ox  =  0.0;
        oy  =  0.0;
        oz  =  0.0;

        oxr =  0.0;
        oyr =  0.0;
        ozr =  0.0;

        sc  =  1.2;
        scr =  0.0;

        t0  =  2000.0;

DREF91: The parameters for the transformation 'IGb14->DREF91' were provided from Peter Franke, BKG, Germany via personal communication:

        dx  =  0.0547;
        dy  =  0.0522;
        dz  = -0.0741;

        dxr =  0.0001;
        dyr =  0.0001;
        dzr = -0.0019;

        // ERTF200  + rotation parameters (ETRF2000 => DREF91)
        ox  =  0.001701 + 0.000658;
        oy  =  0.010290 - 0.000208;
        oz  = -0.016632 + 0.000755;

        oxr =  0.000081;
        oyr =  0.000490;
        ozr = -0.000729;

        sc  =  2.12;
        scr =  0.11;

        t0  =  2010.0;

Custom: Feel free to specify your own 14 Helmert Transformation parameters for transformations from IGS20/ITRF2020 into your own target system.

Figure 30: Setting BNC's Custom Transformation Parameters window

#### 2.15.4 Format - mandatory if 'Host' is set

BNC may upload the Broadcast Correction streams using different Formats. Supported are:

- IGS-SSR which was developed within the IGS Real-Time Working Group (https://files.igs.org/pub/data/format/igs_ssr_v1.pdf), and
- RTCM-SSR which stands for the standardized and proposed SSR Messages which are developed within the RTCM SC-104 Working Group 'State Space Representation' (https://rtcm.myshopify.com/collections/differential-global-navigation-satellite-dgnss-standards).

#### 2.15.5 Center of Mass - optional

BNC allows to either refer Broadcast Corrections to the satellite's Center of Mass (CoM) or to the satellite's Antenna Phase Center (APC). By default, corrections refer to APC. Tick 'Center of Mass' to refer uploaded corrections to CoM.

#### 2.15.6 SP3 File - optional

Specify a path for saving the generated orbit corrections as SP3 orbit files (http://epncb.eu/ftp/data/format/sp3d.pdf). The following is a path example for a Linux system:

       /home/user/BKG0MGXRTS${V3PROD}.SP3

If the specified directory does not exist, BNC will not create SP3 orbit files.

For file naming, BNC follows the new format convention according to IGS products http://acc.igs.org/repro3/Long_Product_Filenames_v1.0.pdf:

      AAAVPPPTTT_YYYYDDDHHMM_LEN_SMP_CNT.FMT

With

AAA | Analysis Center abbrevaition, here BKG
V | Version / Solution identifier (0-9), here 0
PPP | Project/Campaign identification, here Multi-GNSS product (MGX)
TTT | Solution Type, here real-time streamed product (RTS)
YYYYDOYHHMM | String representing beginning time of nominal data interval
LEN | Intended product period of the file
SMP | Data sampling rate
CNT | Content type ORB
FMT | File format, here SP3

Note that '${V3PROD}' produces the part 'YYYYDDDHHMM_LEN_SMP_CNT' of the filename according the 'Upload Corrections' setup.

A result for examle is:

      BKG0MGXRTS_20223330000_01D_01M_ORB.SP3

Default is an empty option field, meaning that you do not want BNC to save the uploaded stream content in daily SP3 files.

As a SP3 file content should be referred to the satellites' Center of Mass (CoM) while Broadcast Corrections are referred to the satellites' APC, an offset has to be applied which is available from an IGS ANTEX file (see option 'ANTEX File' below). Hence, you should specify the 'ANTEX File' path there if you want to save the stream content in SP3 format. If you do not specify an 'ANTEX File' path, the SP3 file content will be referred to the satellites APCs.

Note that clocks in the SP3 orbit files are not corrected for the conventional periodic relativistic effect.

In case the 'Combine Corrections' table contains only one Broadcast Correction stream, BNC will merge that stream with Broadcast Ephemeris to save results in files specified here through SP3 and/or Clock RINEX file path. In such a case you have to define only the SP3 and Clock RINEX file path and no further option in the 'Upload Corrections' table.

Note that BNC outputs a complete list of SP3 'Epoch Header Records', even if no 'Position and Clock Records' are available for certain epochs because of stream outages. Note further that the 'Number of Epochs' in the first SP3 header record may not be correct because that number is not available when the file is created. Depending on your processing software (e.g. Bernese GNSS Software, BSW) it could therefore be necessary to correct an incorrect 'Number of Epochs' in the file before you use it in post processing.

#### 2.15.7 RNX File - optional

The clock corrections generated by BNC for upload can be logged in Clock RINEX format https://files.igs.org/pub/data/format/rinex_clock304.txt:.

Specify a path for saving the generated clock corrections as Clock RINEX files. The following is a path example for a Linux system:

       /home/user/BKG0MGXRTS${V3PROD}.CLK

If the specified directory does not exist, BNC will not create Clock RINEX files.

For file naming, BNC follows the new format convention according to IGS products http://acc.igs.org/repro3/Long_Product_Filenames_v1.0.pdf:

      AAAVPPPTTT_YYYYDDDHHMM_LEN_SMP_CNT.FMT

With

AAA | Analysis Center abbrevaition, here BKG
V | Version / Solution identifier (0-9), here 0
PPP | Project/Campaign identification, here Multi-GNSS product (MGX)
TTT | Solution Type, here real-time streamed product (RTS)
YYYYDOYHHMM | String representing beginning time of nominal data interval
LEN | Intended product period of the file
SMP | Data sampling rate
CNT | Content type CLK
FMT | File format, here CLK

Note that '${V3PROD}' produces the part 'YYYYDDDHHMM_LEN_SMP_CNT' of the filename according the 'Upload Corrections' setup.

A result for examle is:

      BKG0MGXRTS_20223330000_01D_05S_CLK.CLK

Default is an empty option field, meaning that you do not want BNC to save the uploaded stream content in daily Clock RINEX files.

Note further that clocks in the Clock RINEX files are not corrected for the conventional periodic relativistic effect.

#### 2.15.8 BSX File - optional

The satellite biases generated by BNC for upload can be logged in SINEX Bias format https://files.igs.org/pub/data/format/sinex_bias_100.pdf:.

Specify a path for saving the generated clock corrections as Clock RINEX files. The following is a path example for a Linux system:

       /home/user/BKG0MGXRTS${V3PROD}.BIA

If the specified directory does not exist, BNC will not create SINEX Bias files.

For file naming, BNC follows the new format convention according to IGS products http://acc.igs.org/repro3/Long_Product_Filenames_v1.0.pdf:

      AAAVPPPTTT_YYYYDDDHHMM_LEN_SMP_CNT.FMT

With

AAA | Analysis Center abbrevaition, here BKG
V | Version / Solution identifier (0-9), here 0
PPP | Project/Campaign identification, here Multi-GNSS product (MGX)
TTT | Solution Type, here real-time streamed product (RTS)
YYYYDOYHHMM | String representing beginning time of nominal data interval
LEN | Intended product period of the file
SMP | Data sampling rate
CNT | Content type, here absolute bias information (ABS)
FMT | File format, here BIA

Note that '${V3PROD}' produces the part 'YYYYDDDHHMM_LEN_SMP_CNT' of the filename according the 'Upload Corrections' setup.

A result for examle is:

      BKG0MGXRTS_20223330000_01D_05S_ABS.BIA

Default is an empty option field, meaning that you do not want BNC to save the uploaded stream content in daily Clock RINEX files.

#### 2.15.9 PID, SID, IOD - optional

When applying Broadcast Ephemeris corrections in a PPP algorithm or in a combination of several correction streams, it is important for the client software to receive information on the continuity of discontinuity of the stream contents. Here you can specify three ID's to describe the contents of your Broadcast Ephemeris correction stream when it is uploaded.

- A 'SSR Provider ID' is issued by RTCM SC-104 on request to identify a SSR service (see e.g.https://software.rtcm-ntrip.org/wiki/SSRProvider) This ID is globally unique. Values vary in the range of 0-65535. Values in the range of 0-255 are reserved for experimental services.
- A provider may generate several Broadcast Ephemeris correction streams with different contents. The 'SSR Solution ID' indicates different SSR services of one SSR provider. Values vary in the range of 0-15.
- A change of the 'IOD SSR' is used to indicate a change in the SSR generating configuration which may be relevant for the rover. Values vary in the range of 0-15.

#### 2.15.10 Interval - mandatory if 'Upload Table' entries specified

Select the length of SP3 Orbit files, Clock RINEX files and SINAX Bias files. The default value is 1 day.

#### 2.15.11 Sampling

BNC requires an orbit corrections sampling interval for the stream to be uploaded and sampling intervals for SP3, Clock RINEX, and SINEX Bias files. The outgoing stream's clock correction sampling interval follows that of incoming corrections and is therefore nothing to be specified here.

#### 2.15.11.1 Orbits (Orb) - mandatory if 'Upload Table' entries specified

Select the stream's orbit correction sampling interval in seconds. A value of 60 sec may be appropriate.

A value of zero '0' tells BNC to upload all orbit correction samples coming in from the real-time GNSS engine along with the clock correction samples to produce combined orbit and clock corrections to Broadcast Ephemeris; for example message type 1060 for GPS.

Configuration examples:

Let us suppose a real-time network engine supporting BNC every 5 sec with GPS Broadcast Corrections for orbits, clocks and code biases in 'RTNET' stream format.

- With 'Sampling Orb' set to '0' BNC will produce

- Every 5 sec a 1059 message for GPS code biases,
- Every 5 sec a 1060 message for combined orbit and clock corrections to GPS Broadcast Ephemeris.

- With 'Sampling Orb' set to '5' BNC will produce

- Every 5 sec a 1057 message for GPS orbit corrections to Broadcast Ephemeris,
- Every 5 sec a 1058 message for GPS clock corrections to Broadcast Ephemeris,
- Every 5 sec a 1059 message for GPS code biases.

- With 'Sampling Orb' set to '10' BNC will produce

- Every 10 sec a 1057 message for GPS orbit corrections to Broadcast Ephemeris,
- Every 5 sec a 1058 message for GPS clock corrections to Broadcast Ephemeris,
- Every 10 sec a 1059 message for GPS code biases.

Note that only when specifying a value of zero '0' (default) for 'Sampling Orb', BNC produces combined orbit and clock correction messages.

#### 2.15.11.2 SP3 - mandatory if 'SP3 File' is specified

Select the SP3 orbit file sampling interval in minutes. A value of 15 min may be appropriate. A value of zero '0' tells BNC to store all available samples into SP3 orbit files.

#### 2.15.11.3 RINEX (RNX) - mandatory if 'RNX File' is specified

Select the Clock RINEX file sampling interval in seconds. A value of 10 sec may be appropriate. A value of zero '0' tells BNC to store all available samples into Clock RINEX files.

#### 2.15.11.4 SINEX (BSX) - mandatory if 'BSX File' is specified

Select the SINEX Bias file sampling interval in seconds. A value of 10 sec may be appropriate. A value of zero '0' tells BNC to store all available samples into SINEX Bias files.

#### 2.15.11 Custom Trafo - optional if 'Upload Table' entries specified

Hit 'Custom Trafo' to specify your own 14 parameter Helmert Transformation instead of selecting a predefined transformation through 'System' button. .

#### 2.15.12 ANTEX File - mandatory if 'SP3 File' is specified

IGS provides a file containing absolute phase center offsets and variations for GNSS satellite and receiver antennas in ANTEX format. Entering the full path to such an ANTEX file is required here for referring the SP3 file content to the satellite's Center of Mass (CoM). If you do not specify an ANTEX file, the SP3 file will contain orbit information which is referred to Antenna Phase Center (APC) instead of CoM.

The following screenshot shows the encoding and uploading of several Broadcast Ephemeris correction streams combined from different AC streams. Combined streams using different SSR formats are uploaded to different Ntrip Broadcasters and referred to different reference systems. Different SSR Provider IDs, SSR Solution IDs and Issue of Data IDs are specified. Required Broadcast Ephemeris are received via stream 'BCEP00BKG0'.

Figure 31: BNC uploading a combined Broadcast Correction stream

#### 2.16 Upload Ephemeris

BNC can generate streams carrying only Broadcast Ephemeris in RTCM Version 3 format and upload them to an Ntrip Broadcaster. The satellite system(s) that shall be part of the uploaded stream can be specified using the 'System' parameter. This can be done:

- for an individual satellite system, specifying e.g. 'G' for GPS or 'E' for Galileo, etc. or
- for a seclection of satellite systems, specifying e.g. 'GRE' for GPS and GLONASS and Galileo or
- for all satellite systems, specifying 'ALL'.

Note that Broadcast Ephemeris received in real-time have a system specific period of validity in BNC, which is defined in accordance with the update rates and validity intervals of the navigation messages. For this, the time difference dt of Time of Clock (TOC) with respect the current time is determined:

       dt = currentTime - TOC [sec]

Hence,

- GPS ephemeris will be interpreted as outdated and ignored when dt > 14400.0 or dt < -7200.0.
- GLONASS ephemeris will be interpreted as outdated and ignored when dt > 3900.0 or dt < -2100.0.
- Galileo ephemeris will be interpreted as outdated and ignored when dt > 14400.0 or dt < 0.0.
- BDS ephemeris will be interpreted as outdated and ignored when dt > 3900.0 or dt < 0.0.
- SBAS ephemeris will be interpreted as outdated and ignored when dt > 600.0 or dt < -600.0.
- QZSS ephemeris will be interpreted as outdated and ignored when dt > 7200.0 or dt < -3600.0.
- IRNSS ephemeris will be interpreted as outdated and ignored when fabs(dt > 86400.0).

A note 'OUTDATED EPHEMERIS' will be given in the logfile and the data will be disregarded when necessary.

Furthermore, received Broadcast Ephemeris parameters pass through a plausibility check in BNC which allows to ignore incorrect ephemeris data when necessary, leaving a note 'WRONG EPHEMERIS' in the logfile. Unhealthy Broadcast Ephemeris will not be excluded. A note 'UNHEALTHY EPHEMERIS' will be added in the logfile.

#### 2.16.1 Host & Port - optional

Specify the 'Host' IP number or URL of an Ntrip Broadcaster to upload the stream. An empty option field means that you do not want to upload Broadcast Ephemeris.

Enter the Ntrip Broadcaster's IP 'Port' number for stream upload. Note that Ntrip Broadcasters are often configured to provide access through more than one port, usually ports 80 and 2101. If you experience communication problems on port 80, you should try to use the alternative port(s).

#### 2.16.2 Mountpoint, Ntrip Version, User, Password - mandatory if 'Host' is set

BNC uploads a stream to the Ntrip Broadcaster by referring it to a dedicated mountpoint that has been set by its operator. Specify the mountpoint based on the details you received for your stream from the operator. It is often a 9-character ID (capital letters) plus an integer number.

For stream upload the Ntrip Version can be chosen. An Ntrip version 1 upload is protected through an upload 'Password' only. For an Ntrip Version 2 upload an upload 'User' is required in addition. Enter the user name and the password you received from the Ntrip Broadcaster operator along with the mountpoint.

#### 2.16.3 Satellite System - mandatory if 'Host' is set

Specify the satellite system(s) that shall be part of the uploaded stream (e.g. 'G' for GPS or 'GRE' for GPS+GLONASS+Galileo, or 'ALL').

#### 2.16.4 Sampling - mandatory if 'Host' is set

Select the Broadcast Ephemeris repetition interval in seconds. Default is '5', meaning that a complete set of Broadcast Ephemeris is uploaded every 5 seconds.

Figure 32: BNC producing Broadcast Ephemeris streams from globally distributed RTCM streams; upload in RTCM format to an Ntrip Broadcaster

#### 2.17 Streams Canvas

Each stream on an Ntrip Broadcaster (and consequently on BNC) is defined using a unique source ID called mountpoint. An Ntrip Client like BNC accesses the desired stream by referring to its mountpoint. Information about streams and their mountpoints is available through the source-table maintained by the Ntrip Broadcaster.

Streams selected for retrieval are listed under the 'Streams' canvas on BNC's main window. The list provides the following information either extracted from source-table(s) produced by the Ntrip Broadcasters or introduced by BNC's user:

'resource loader' | Ntrip Broadcaster URL and port, or TCP/IP host and port, or UDP port, or Serial input port specification.
'mountpoint' | Mountpoint introduced by Ntrip Broadcaster, or Mountpoint introduced by BNC's user.
'decoder' | Name of decoder used to handle the incoming stream content according to its format; editable.
'lat' | Approximate latitude of reference station, in degrees, north; editable if 'nmea' = 'yes'.
'long' | Approximate longitude of reference station, in degrees, east; editable if 'nmea' = 'yes'.
'nmea' | Indicates whether or not streaming needs to be initiated by BNC through sending NMEA-GGA message carrying position coordinates in 'lat' and 'long'.
'ntrip' | Selected Ntrip transport protocol version (1, 2, 2s, R, or U), or 'N' for TCP/IP streams without Ntrip, or 'UN' for UDP streams without Ntrip, or 'S' for serial input streams without Ntrip.
'bytes' | Number of bytes received.

#### 2.17.1 Edit Streams

- BNC automatically allocates one of its internal decoders to a stream based on the stream's 'format' and 'format-details' as given in the source-table. However, there might be cases where you need to override the automatic selection due to an incorrect source-table for example. BNC allows users to manually select the required decoder by editing the decoder string. Double click on the 'decoder' field, enter your preferred decoder and then hit Enter. Accepted decoder strings are 'RTCM_2.x', 'RTCM_3.x' and 'RTNET'.
- In case you need to log the raw data as it is, BNC allows users to by-pass its decoders and directly save the input in daily logfiles. To do this, specify the decoder string as 'ZERO'. The generated filenames are created from the characters of the streams mountpoints plus two-digit numbers each for year, month, and day. Example: Setting the 'decoder' string for mountpoint WTZZ00DEU0 to 'ZERO' and running BNC on December 01, 2022 would save raw data in a file named WTZZ00DEU0_221201.
- BNC can also retrieve streams from virtual reference stations (VRS). To initiate these streams, an approximate rover position needs to be sent in NMEA format to the Ntrip Broadcaster. In return, a user-specific data stream is generated, typically by Network RTK software. VRS streams are indicated by a 'yes' in the source-table as well as in the 'nmea' column on the 'Streams' canvas in BNC's main window. They are customized exactly to the latitude and longitude transmitted to the Ntrip Broadcaster via NMEA GGA sentences. If NMEA GGA sentences are not coming from a serially connected GNSS rover, BNC simulates them from the default latitude and longitude of the source-table as shown in the 'lat' and 'long' columns on the 'Streams' canvas. However, in many cases you would probably want to change these defaults according to your requirement. Double-click on 'lat' and 'long' fields, enter the values you wish to send and then hit Enter. The format is in positive north latitude degrees (e.g. for northern hemisphere: 52.436, for southern hemisphere: -24.567) and eastern longitude degrees (example: 358.872 or -1.128). Only streams with a 'yes' in their 'nmea' column can be edited. The position should preferably be a point within the VRS service area of the network. RINEX files generated from these streams will contain an additional COMMENT line in the header beginning with 'NMEA' showing the 'lat' and 'long' used. Note that when running BNC in a Local Area Network (LAN), NMEA strings may be blocked by a proxy server, firewall or virus scanner when not using the Ntrip Version 2 transport protocol.

#### 2.17.2 Delete Stream

To remove a stream from the 'Streams' canvas in the main window, highlight it by clicking on it and hit the 'Delete Stream' button. You can also remove multiple streams simultaneously by highlighting them using +Shift or +Ctrl.

#### 2.17.3 Reconfigure Stream Selection On-the-fly

The streams selection can be changed on-the-fly without interrupting uninvolved threads in the running BNC process.

Window mode: Hit 'Reread & Save Configuration' while BNC is in window mode and already processing data to let changes of your stream selection immediately become effective.

No window mode: When operating BNC online in 'no window' mode (command line option -nw), you force BNC to reread its 'mountPoints' configuration option from disk at pre-defined intervals. Select '1 min', '1 hour', or '1 day' as 'Reread configuration' option to reread the 'mountPoints' option every full minute, hour, or day. This lets a 'mountPoints' option edited in between in the configuration file become effective without terminating uninvolved threads. See section 'Configuration Examples' for configuration file examples and section 'Reread Configuration' for a list of other on-the-fly changeable options.

#### 2.18 Logging Canvas

The 'Logging Canvas' above the bottom menu bar on the main window labeled 'Log', 'Throughput', 'Latency', and 'PPP Plot' provides control of BNC's activities. Tabs are available for continuously showing logfile content, for a plot controlling the bandwidth consumption, a plot showing stream latencies, and for time series plots of PPP results.

#### 2.18.1 Log

Records of BNC's activities are shown in the 'Log' tab. They can be saved into a file when a valid path is specified in the 'Logfile (full path)' field.

#### 2.18.2 Throughput

The bandwidth consumption per stream is shown in the 'Throughput' tab in bits per second (bps) or kilobits per second (kbps). The following figure shows an example for the bandwidth consumption of incoming streams.

Figure 33: Bandwidth consumption of RTCM streams received by BNC

#### 2.18.3 Latency

The latency of observations in each incoming stream is shown in the 'Latency' tab in milliseconds or seconds. Streams not carrying observations (e.g. those providing only Broadcast Ephemeris messages) or having an outage are not considered here and shown in red color. Note that the calculation of correct latencies requires the clock of the host computer to be properly synchronized. The next figure shows an example for the latency of incoming streams.

Figure 34: Latency of RTCM streams received by BNC

#### 2.18.4 PPP Plot

Precise Point Positioning time series of North (red), East (green) and Up (blue) coordinate components are shown in the 'PPP Plot' tab when a 'Mountpoint' option is defined under PPP (4). Values are referred to a priori reference coordinates. The time as given in format [hh:mm] refers to GPS Time. The sliding PPP time series window covers a period of 5 minutes. Note that it may take up to 30 seconds or more until the first PPP solutions becomes available. The following figure shows the screenshot of a PPP time series plot of North, East and Up coordinate displacements.

Figure 35: Example for time series plot of displacements produced by BNC

#### 2.19 Bottom Menu Bar

The bottom menu bar allows to add or delete streams to or from BNC's configuration and to start or stop it. It also provides access to BNC's online help function. The 'Add Stream' button opens a window that allows users to select one of several input communication links, see figure below.

Figure 36: Steam input communication links accepted by BNC

#### 2.19.1 Add Stream

Button 'Add Stream' allows you to pull streams either from an Ntrip Broadcaster or from a TCP/IP port, UPD port, or serial port.

#### 2.19.1.1 Add Stream - Coming from Caster

Button 'Add Stream' > 'Coming from Caster' opens a window that allows users to select data streams from an Ntrip Broadcaster according to their mountpoints and show a distribution map of offered streams.

#### 2.19.1.1.1 Caster Host and Port - mandatory

Enter the Ntrip Broadcaster host IP and port number. Note that EUREF and IGS operate Ntrip Broadcasters https://euref-ip.net/home, https://igs-ip.net/home and https://products.igs-ip.net/home.

#### 2.19.1.1.2 Casters Table - optional

It may be that you are not sure about your Ntrip Broadcaster's host and port number or you are interested in other broadcaster installations operated elsewhere. Hit 'Show' for a table of known broadcasters maintained at https://rtcm-ntrip.org/home . A window opens which allows selecting a broadcaster for stream retrieval, see figure below.

Figure 37: BNC's 'Select Broadcaster' table

#### 2.19.1.1.3 User and Password - mandatory for protected streams

Streams on Ntrip Broadcasters may be protected. Enter a valid 'User' ID and 'Password' for access to protected streams. Accounts are usually provided per Ntrip Broadcaster through a registration procedure. Register through https://register.rtcm-ntrip.org for access to protected streams from EUREF and IGS.

#### 2.19.1.1.4 Get Table

Use the 'Get Table' button to download the source-table from the Ntrip Broadcaster. Pay attention to data fields 'format' and 'format-details'. Keep in mind that BNC can only decode and convert streams that come in RTCM Version 2, RTCM Version 3, or RTNET format. For access to observations, Broadcast Ephemerides and Broadcast Corrections in RTCM format, streams must contain a selection of appropriate message types as listed in the Annex; cf. data field 'format-details' for available message types and their repetition rates in brackets. Note that in order to produce RINEX Navigation files, RTCM Version 3 streams containing message types

- 1019 (GPS) or
- 1020 (GLONASS) or
- 1041 (IRNSS) or
- 1042 (BDS/BeiDou) or
- 1043 (SBAS) or
- 1044 (QZSS) or
- 1045 (Galileo F/NAV) or
- 1046 (Galileo I/NAV).

are required. Select your streams line by line, use +Shift and +Ctrl when necessary. The figure below provides an example source-table.

The content of data field 'nmea' tells you whether a stream retrieval needs to be initiated by BNC through sending an NMEA-GGA message carrying approximate position coordinates (Virtual Reference Station, VRS).

Hit 'OK' to return to the main window. If you wish, you can click on 'Add Stream' and repeat the process of retrieving streams from different casters.

Figure 38: Broadcaster source-table shown by BNC

#### 2.19.1.1.5 Ntrip Version - mandatory

Some limitations and deficiencies of the Ntrip Version 1 stream transport protocol are solved in Ntrip Version 2. Improvements mainly concern a full HTTP compatibility in view of requirements coming from proxy servers. Version 2 is backwards compatible to Version 1. Options implemented in BNC are:

Option | Meaning
1 | Ntrip Version 1, TCP/IP
2 | Ntrip Version 2 in TCP/IP mode
2s | Ntrip Version 2 in TCP/IP mode via SSL
R | Ntrip Version 2 in RTSP/RTP mode
U | Ntrip Version 2 in UDP mode

Try using option '2' if your streams are otherwise blocked by a proxy server operated in front of BNC.

When using Ntrip Version 2 via SSL (option '2s') you need to specify the appropriate 'Caster port' for that. It is usually port number 443. Clarify 'SSL' options offered in panel 'Network'.

Option 'R' or 'U' may be selected if latency is more important than completeness for your application. Note that the latency reduction is likely to be in the order of 0.5 sec or less. Note further that options 'R' (RTSP/RTP mode) and 'U' (UDP mode) are not accepted by proxy servers and a mobile Internet Service Provider may not support it.

#### 2.19.1.1.6 Map - optional

Button 'Map' opens a window to show a distribution map of the caster's streams. You may like to zoom in or out using the mouse. Left button: draw a rectangle to zoom, right button: zoom out, middle button: zoom back.

Figure 39: Stream distribution map shown by BNC as derived from Ntrip Broadcaster source-table

#### 2.19.1.2 Add Stream - Coming from TCP/IP Port

Button 'Add Stream' > 'Coming from TCP/IP Port' allows to retrieve streams via TCP directly from an IP address without using the Ntrip transport protocol. For that you:

- Enter the IP address of the stream providing host.
- Enter the IP port number of the stream providing host.
- Specify a mountpoint. Recommended is a 9-character station ID. Example: FFMJ00DEU
- Specify the stream format. Available options are 'RTCM_2', 'RTCM_3', 'RTNET', and 'ZERO'.
- Enter the approximate latitude of the stream providing rover in degrees. Example: 50.09.
- Enter the approximate longitude of the stream providing rover in degrees. Example: 8.66.

Streams directly received from a TCP/IP port show up with an 'N' for 'No Ntrip' in the 'Streams' canvas on BNC's main window. Latitude and longitude are to be entered just for informal reasons.

Note that this option works only if no proxy server is involved in the communication link.

#### 2.19.1.3 Add Stream - Coming from UDP Port

Button 'Add Stream' > 'Coming from UDP Port' allows to pick up streams arriving directly at one of the local host's UDP ports without using the Ntrip transport protocol. For that you:

- Enter the local port number where the UDP stream arrives.
- Specify a mountpoint. Recommended is a 9-character station ID. Example: FFMJ00DEU
- Specify the stream format. Available options are 'RTCM_2', 'RTCM_3', 'RTNET', and 'ZERO'.
- Enter the approximate latitude of the stream providing rover in degrees. Example: 50.09.
- Enter the approximate longitude of the stream providing rover in degrees. Example: 8.66.

Streams directly received at a UDP port show up with a 'UN' for 'UDP, No Ntrip' in the 'Streams' canvas section on BNC's main window. Latitude and longitude are to be entered just for informal reasons.

#### 2.19.1.4 Add Stream - Coming from Serial Port

Button 'Add Stream' > 'Coming from Serial Port' allows to retrieve streams from a GNSS receiver via serial port without using the Ntrip transport protocol. For that you:

- Specify a mountpoint. Recommended is a 9-character station ID. Example: FFMJ00DEU
- Specify the stream format. Available options are 'RTCM_2', 'RTCM_3', 'RTNET', and 'ZERO'.
- Enter the approximate latitude of the stream providing rover in degrees. Example: 50.09.
- Enter the approximate longitude of the stream providing rover in degrees. Example: 8.66.
- Enter the serial 'Port name' selected on your host for communication with the receiver. Valid port names are

  Windows: | COM1, COM2
  Linux: | /dev/ttyS0, /dev/ttyS1
  FreeBSD: | /dev/ttyd0, /dev/ttyd1
  Digital Unix: | /dev/tty01, /dev/tty02
  HP-UX: | /dev/tty1p0, /dev/tty2p0
  SGI/IRIX; | /dev/ttyf1, /dev/ttyf2
  SunOS/Solaris: | /dev/ttya, /dev/ttyb

- Select a 'Baud rate' for the serial input. Note that using a high baud rate is recommended.
- Select the number of 'Data bits' for the serial input. Note that often '8' data bits are used.
- Select the 'Parity' for the serial input. Note that parity is often set to 'NONE'.
- Select the number of 'Stop bits' for the serial input. Note that often '1' stop bit is used.
- Select a 'Flow control' for the serial link. Select 'OFF' if you do not know better.

When selecting one of the serial communication options listed above, make sure that you pick those configured to the serially connected GNSS receiver.

Streams received from a serially connected GNSS receiver show up with an 'S' (for Serial Port, no Ntrip) in the 'Streams' canvas section on BNC's main window. Latitude and longitude are to be entered just for informal reasons.

The following figure shows a BNC example setup for pulling a stream via serial port on a Windows operating system.

Figure 40: BNC configuration for pulling a stream via serial port

#### 2.19.2 Delete Stream

Button 'Delete Stream' allows you to delete streams previously selected for retrieval as listed under the 'Streams' canvas on BNC's main window.

#### 2.19.3 Map

Button 'Map' opens a window to show a distribution map of the streams selected for retrieval as listed under the 'Streams' canvas. You may like to zoom in or out using the mouse. Left button: draw a rectangle to zoom, right button: zoom out, middle button: zoom back.

#### 2.19.4 Start

Hit 'Start' to start retrieving, decoding or converting GNSS data streams in real-time. Note that 'Start' generally forces BNC to begin with fresh RINEX files which might overwrite existing files when necessary unless option 'Append files' is ticked.

#### 2.19.5 Stop

Hit the 'Stop' button in order to stop BNC.

#### 2.19.6 Help? = Shift+F1

BNC comes with a What's This help system providing information about its functionality and usage. Short descriptions are available for any widget and program option. Focus to the relevant object and press Shift+F1 to request help information. A help text appears immediately; it disappears as soon as the user does something else. The dialogs on some operating systems may provide a '?' button that users can click; click the relevant widget to pop up the help text.

#### 2.20 Command Line Options

Command line options are available to run BNC in 'no window' mode or let it read previously recorded input offline from one or several files for debugging or post processing purposes. It is also possible to introduce a specific configuration filename instead of using the default filename 'BNC.bnc'. The self-explaining content of the configuration file can easily be edited.

In addition to reading processing options from the involved configuration file, BNC can optionally read any configuration option from command line. Running BNC with command line option 'help'

Example:
bnc --help (MS Windows: bnc.exe --help | more)

provides a list of all available command line options.

#### 2.20.1 Version - optional

Command line option '--version' lets BNC print its version number.

Example:
bnc --version (MS Windows: bnc.exe --version | more)

#### 2.20.2 Display - optional

On systems which support graphics, command line option '--display' forces BNC to present the BNC window on the specified display.

Example:
bnc.exe --display localhost:10.0

#### 2.20.3 No Window Mode - optional

Apart from its regular windows mode, BNC can be started on all systems as a batch job with command line option '-nw'. BNC will then run in 'no window' mode, using processing options from its configuration file on disk. Terminate BNC using Windows Task Manager when running it in 'no window' mode on Windows systems.

Example:
bnc.exe --nw

The following Linux command line produces RINEX QC plots (see Estey and Meertens 1999) offline in 'no window' mode and saves them in directory '/home/user'. Introducing a dummy configuration file /dev/null makes sure that no configuration options previously saved on disc are used: It is obvious that BNC requires graphics support when started in interactive mode. However, note that graphics support is also required when producing plots in batch mode (option -nw). Windows and Mac OS X systems always support graphics. For producing plots in batch mode on Linux systems you must make sure that at least a virtual X-Server such as 'Xvfb' is installed and the '-display' option is used. The following is an example shell script to execute BNC in batch mode for producing QC plots from RINEX files. It could be used via 'crontab':

    #!/bin/bash

    ../bnc -nw -conf /dev/null -display :1 --platform offscreen\
           -key reqcAction Analyze \
           -key reqcObsFile Input/MAO000USA_R_20221720000_01D_30S_MO.rnx \
           -key reqcNavFile Input/MAO000USA_R_20221720000_01D_MN.rnx \
           -key reqcSkyPlotSignals "G:1&2&5 R:1&2 E:1&5&7 C:2&6 J:1&2" \
           -key reqcOutLogFile Output/RinexQc.log \
           -key reqcPlotDir Output 2>/dev/null

#### 2.20.4 File Mode - optional

Although BNC is primarily a real-time online tool, for debugging purposes it can be run offline to read data from a file previously saved through option 'Raw output file' (Record & Replay functionality). Enter the following command line option for that

--file <inputFileName>

and specify the full path to an input file containing previously saved data. Example:
./bnc --file /home/user/raw.output_221202

Note that when running BNC offline, it will use options for file saving, interval, sampling, PPP etc. from its configuration file.

Note further that option '--file' forces BNC to apply the '-nw' option for running in 'no window' mode.

#### 2.20.5 Configuration File - optional

The default configuration filename is 'BNC.bnc'. You may change this name at startup time using command line option '--conf <confFileName>'. This allows running several BNC jobs in parallel on the same host using different sets of configuration options. confFileName stands either for the full path to a configuration file or just for a filename. If you introduce only a filename, the corresponding file will be saved in the current working directory from where BNC is started.

Example:
./bnc --conf MyConfig.bnc

This leads to a BNC job using configuration file 'MyConfig.bnc'. The configuration file will be saved in the current working directory.

#### 2.20.6 Configuration Options - optional

BNC applies options from the configuration file but allows updating every one of them on the command line while the content of the configuration file remains unchanged. Note the following syntax for Command Line Interface (CLI) options:

--key <keyName> <keyValue>

Parameter <keyName> stands for the key name of an option contained in the configuration file and <keyValue> stands for the value you want to assign to it. The following is a syntax example for a complete command line:

bnc --nw --conf <confFileName> --key <keyName1> <keyValue1> --key <keyName2> <keyValue2> ...

Configuration options which are part of the configuration files PPP section must be prefixed by 'PPP/'. As an example, option 'minObs' from the PPP section of the BNC configuration file would be specified as

'PPP/minObs'

on a command line.

Values for configuration options can be introduced via command line exactly as they show up in the configuration file. However, any value containing one or more blank characters must be enclosed by quotation marks when specified on command line.

### 3. Annex

#### 3.1 RTCM Standards

The Radio Technical Commission for Maritime Services (RTCM) is an international non-profit scientific, professional and educational organization. Special Committees provide a forum in which governmental and non-governmental members work together to develop technical standards and consensus recommendations in regard to issues of particular concern. RTCM is engaged in the development of international standards for maritime radionavigation and radiocommunication systems. The output documents and reports prepared by RTCM Committees are published as RTCM Recommended Standards. Topics concerning Differential Global Navigation Satellite Systems (DGNSS) are handled by the Special Committee SC 104.

Personal copies of RTCM Recommended Standards can be ordered through https://rtcm.myshopify.com/collections/differential-global-navigation-satellite-dgnss-standards

#### 3.1.1 Ntrip Version 1

'Networked Transport of RTCM via Internet Protocol' Version 1.0 (Ntrip) stands for an application-level protocol streaming Global Navigation Satellite System (GNSS) data over the Internet. Ntrip is a generic, stateless protocol based on the Hypertext Transfer Protocol HTTP/1.1. The HTTP objects are enhanced to GNSS data streams.

Ntrip Version 1 is an RTCM standard designed for disseminating differential correction data (e.g. in the RTCM-104 format) or other kinds of GNSS streaming data to stationary or mobile users over the Internet, allowing simultaneous PC, Laptop, PDA, or receiver connections to a broadcasting host. Ntrip supports wireless Internet access through Mobile IP Networks like GSM, GPRS, EDGE, or UMTS.

Ntrip is implemented in three system software components: Ntrip Clients, Ntrip Servers and Ntrip Broadcasters. The Ntrip Broadcaster is the actual HTTP server program whereas Ntrip Client and Ntrip Server are acting as HTTP clients.

Ntrip is an open none-proprietary protocol. Major characteristics of Ntrip's dissemination technique are:

- Based on the popular HTTP streaming standard; comparatively easy to implement when having limited client and server platform resources available;
- Application not limited to one particular plain or coded stream content; ability to distribute any kind of GNSS data;
- Potential to support mass usage; disseminating hundreds of streams simultaneously for thousands of users possible when applying modified Internet Radio broadcasting software;
- Considering security needs; stream providers and users do not necessarily get into contact, streams often not blocked by firewalls or proxy servers protecting Local Area Networks;
- Enables streaming over mobile IP networks because of using TCP/IP.

The Ntrip Broadcaster maintains a source-table containing information on available Ntrip streams, networks of Ntrip streams and Ntrip Broadcasters. See at https://software.rtcm-ntrip.org/wiki/Sourcetable for details.

Source-table records are dedicated to one of the following:

- Data Streams (record type STR, for details see at: https://software.rtcm-ntrip.org/wiki/STR
- Casters (record type CAS, for details see at: https://software.rtcm-ntrip.org/wiki/CAS
- Networks of streams (record type NET, for details see at: https://software.rtcm-ntrip.org/wiki/NET

The source-table is sent to an Ntrip Client on request.

#### 3.1.2 Ntrip Version 2

The major changes of Ntrip Version 2 compared to Version 1.0 are:

- Cleared and fixed design problems and HTTP protocol violations;
- Replaced nonstandard directives;
- Chunked transfer encoding;
- Improvements in header records;
- Source-table filtering;
- RTSP communication.

Ntrip Version 2 allows to communicate either in TCP/IP mode or in RTSP/RTP mode or in UDP mode whereas Version 1 is limited to TCP/IP only.

It furthermore allows using the Transport Layer Security (TLS) for secure Ntrip communication over the Internet.

#### 3.1.3 RTCM Version 2

Transmitting GNSS carrier phase data can be done through RTCM Version 2 messages. Please note that only RTCM Version 2.2 and 2.3 streams may include GLONASS data. Messages that may be of interest here are:

- Type 1 message is the range correction message and is the primary message in code-phase differential positioning (DGPS). It is computed in the base receiver by computing the error in the range measurement for each tracked SV.
- Type 2 message is automatically generated when a new set of satellite ephemeris is downloaded to the base receiver. It is the computed difference between the old ephemeris and the new ephemeris. Type 2 messages are used when the base station is transmitting Type 1 messages.
- Type 3 and 22 messages are the base station position and the antenna offset. Type 3 and 22 are used in RTK processing to perform antenna reduction.
- Type 6 message is a null frame filler message that is provided for data links that require continuous transmission of data, even if there are no corrections to send. As many Type 6 messages are sent as required to fill in the gap between two correction messages (type 1). Message 6 is not sent in burst mode.
- Type 9 message serves the same purpose as Type 1, but does not require a complete satellite set. As a result, Type 9 messages require a more stable clock than a station transmitting Type 1 's, because the satellite corrections have different time references.
- Type 16 message is simply a text message entered by the user that is transmitted from the base station to the rover. It is used with code-phase differential.
- Type 18 and 20 messages are RTK uncorrected carrier phase data and carrier phase corrections.
- Type 19 and 21 messages are the uncorrected pseudo-range measurements and pseudo-range corrections used in RTK.
- Type 23 message provides the information on the antenna type used on the reference station.
- Type 24 message carries the coordinates of the installed antenna's ARP in the GNSS coordinate system coordinates.

#### 3.1.4 RTCM Version 3

RTCM Version 3 has been developed as a more efficient alternative to RTCM Version 2. Service providers and vendors have asked for a standard that would be more efficient, easy to use, and more easily adaptable to new situations. The main complaint was that the Version 2 parity scheme was wasteful of bandwidth. Another complaint was that the parity is not independent from word to word. Still another was that even with so many bits devoted to parity, the actual integrity of the message was not as high as it should be. Plus, 30-bit words are awkward to handle. The Version 3 standard is intended to correct these weaknesses.

RTCM Version 3 defines a number of message types. Messages that may be of interest here are:

- Type 1001, GPS L1 code and phase.
- Type 1002, GPS L1 code and phase and ambiguities and carrier-to-noise ratio.
- Type 1003, GPS L1 and L2 code and phase.
- Type 1004, GPS L1 and L2 code and phase and ambiguities and carrier-to-noise ratio.
- Type 1005, Station coordinates XYZ for antenna reference point.
- Type 1006, Station coordinates XYZ for antenna reference point and antenna height.
- Type 1007, Antenna descriptor and ID.
- Type 1008, Antenna serial number.
- Type 1009, GLONASS L1 code and phase.
- Type 1010, GLONASS L1 code and phase and ambiguities and carrier-to-noise ratio.
- Type 1011, GLONASS L1 and L2 code and phase.
- Type 1012, GLONASS L1 and L2 code and phase and ambiguities and carrier-to-noise ratio.
- Type 1013, Modified Julian Date, leap second, configured message types and interval.
- Type 1019, GPS ephemeris.
- Type 1020, GLONASS ephemeris.
- Type 1041 IRNSS ephemeris.
- Type 1042, BDS/BeiDou ephemeris.
- Type 1043, SBAS ephemeris.
- Type 1044, QZSS ephemeris.
- Type 1045, Galileo F/NAV ephemeris.
- Type 1046, Galileo I/NAV ephemeris.
- Type 4076, Proprietary messages of the International IGS Service.

The following are so-called 'State Space Representation' (SSR) messages defined or proposed within RTCM SC-104:

- Type 1057, GPS orbit corrections to Broadcast Ephemeris
- Type 1058, GPS clock corrections to Broadcast Ephemeris
- Type 1059, GPS code biases
- Type 1060, Combined orbit and clock corrections to GPS Broadcast Ephemeris
- Type 1061, GPS User Range Accuracy (URA)
- Type 1062, High-rate GPS clock corrections to Broadcast Ephemeris
- Type 1063, GLONASS orbit corrections to Broadcast Ephemeris
- Type 1064, GLONASS clock corrections to Broadcast Ephemeris
- Type 1065, GLONASS code biases
- Type 1066, Combined orbit and clock corrections to GLONASS Broadcast Ephemeris
- Type 1067, GLONASS User Range Accuracy (URA)
- Type 1068, High-rate GLONASS clock corrections to Broadcast Ephemeris
- Type 1240, Galileo orbit corrections to Broadcast Ephemeris
- Type 1241, Galileo clock corrections to Broadcast Ephemeris
- Type 1242, Galileo code biases
- Type 1243, Combined orbit and clock corrections to Galileo Broadcast Ephemeris
- Type 1244, Galileo User Range Accuracy (URA)
- Type 1245, High-rate Galileo clock corrections to Broadcast Ephemeris
- Type 1246, QZSS orbit corrections to Broadcast Ephemeris
- Type 1247, QZSS clock corrections to Broadcast Ephemeris
- Type 1248, QZSS code biases
- Type 1249, Combined orbit and clock corrections to QZSS Broadcast Ephemeris
- Type 1250, QZSS User Range Accuracy (URA)
- Type 1251, High-rate QZSS clock corrections to Broadcast Ephemeris
- Type 1252, SBAS orbit corrections to Broadcast Ephemeris
- Type 1253, SBAS clock corrections to Broadcast Ephemeris
- Type 1254, SBAS code biases
- Type 1255, Combined orbit and clock corrections to SBAS Broadcast Ephemeris
- Type 1256, SBAS User Range Accuracy (URA)
- Type 1257, High-rate SBAS clock corrections to Broadcast Ephemeris
- Type 1258, BDS orbit corrections to Broadcast Ephemeris
- Type 1259, BDS clock corrections to Broadcast Ephemeris
- Type 1260, BDS code biases
- Type 1261, Combined orbit and clock corrections to BDS Broadcast Ephemeris
- Type 1262, BDS User Range Accuracy (URA)
- Type 1263, High-rate BDS clock corrections to Broadcast Ephemeris
- Type 1264 SSR Ionosphere VTEC Spherical Harmonics
- Type 1265 SSR GPS Satellite Phase Bias
- Type 1266 SSR Satellite GLONASS Phase Bias
- Type 1267 SSR Satellite Galileo Phase Bias
- Type 1268 SSR Satellite QZSS Phase Bias
- Type 1269 SSR Satellite SBAS Phase Bias
- Type 1270 SSR Satellite BDS Phase Bias

The following are so-called 'Multiple Signal Messages' (MSM) defined within RTCM SC-104:

- Type 1071, Compact GPS pseudo-ranges
- Type 1072, Compact GPS carrier phases
- Type 1073, Compact GPS pseudo-ranges and carrier phases
- Type 1074, Full GPS pseudo-ranges and carrier phases plus signal strength
- Type 1075, Full GPS pseudo-ranges, carrier phases, Doppler and signal strength
- Type 1076, Full GPS pseudo-ranges and carrier phases plus signal strength (high resolution)
- Type 1077, Full GPS pseudo-ranges, carrier phases, Doppler and signal strength (high resolution)
- Type 1081, Compact GLONASS pseudo-ranges
- Type 1082, Compact GLONASS carrier phases
- Type 1083, Compact GLONASS pseudo-ranges and carrier phases
- Type 1084, Full GLONASS pseudo-ranges and carrier phases plus signal strength
- Type 1085, Full GLONASS pseudo-ranges, carrier phases, Doppler and signal strength
- Type 1086, Full GLONASS pseudo-ranges and carrier phases plus signal strength (high resolution)
- Type 1087, Full GLONASS pseudo-ranges, carrier phases, Doppler and signal strength (high resolution)
- Type 1091, Compact Galileo pseudo-ranges
- Type 1092, Compact Galileo carrier phases
- Type 1093, Compact Galileo pseudo-ranges and carrier phases
- Type 1094, Full Galileo pseudo-ranges and carrier phases plus signal strength
- Type 1095, Full Galileo pseudo-ranges, carrier phases, Doppler and signal strength
- Type 1096, Full Galileo pseudo-ranges and carrier phases plus signal strength (high resolution)
- Type 1097, Full Galileo pseudo-ranges, carrier phases, Doppler and signal strength (high resolution)
- Type 1101, Compact SBAS pseudo-ranges
- Type 1102, Compact SBAS carrier phases
- Type 1103, Compact SBAS pseudo-ranges and carrier phases
- Type 1104, Full SBAS pseudo-ranges and carrier phases plus signal strength
- Type 1105, Full SBAS pseudo-ranges, carrier phases, Doppler and signal strength
- Type 1106, Full SBAS pseudo-ranges and carrier phases plus signal strength (high resolution)
- Type 1107, Full SBAS pseudo-ranges, carrier phases, Doppler and signal strength (high resolution)
- Type 1121, Compact BeiDou pseudo-ranges
- Type 1122, Compact BeiDou carrier phases
- Type 1123, Compact BeiDou pseudo-ranges and carrier phases
- Type 1124, Full BeiDou pseudo-ranges and carrier phases plus signal strength
- Type 1125, Full BeiDou pseudo-ranges, carrier phases, Doppler and signal strength
- Type 1126, Full BeiDou pseudo-ranges and carrier phases plus signal strength (high resolution)
- Type 1127, Full BeiDou pseudo-ranges, carrier phases, Doppler and signal strength (high resolution)
- Type 1111, Compact QZSS pseudo-ranges
- Type 1112, Compact QZSS carrier phases
- Type 1113, Compact QZSS pseudo-ranges and carrier phases
- Type 1114, Full QZSS pseudo-ranges and carrier phases plus signal strength
- Type 1115, Full QZSS pseudo-ranges, carrier phases, Doppler and signal strength
- Type 1116, Full QZSS pseudo-ranges and carrier phases plus signal strength (high resolution)
- Type 1117, Full QZSS pseudo-ranges, carrier phases, Doppler and signal strength (high resolution)

#### 3.2 Command Line Help

Command line option '--help' provides a complete list of all configuration parameters which can be specified via BNC's Command Line Interface (CLI). Note that command line options overrule configuration options specified in the configuration file. The following is the output produced when running BNC with command line option '--help':

    Usage:
       bnc --help (MS Windows: bnc.exe --help | more)
           --nw
           --version (MS Windows: bnc.exe --version | more)
           --display {name}
           --conf {confFileName}
           --file {rawFileName}
           --key  {keyName} {keyValue}

    Network Panel keys:
       proxyHost         {Proxy host, name or IP address [character string]}
       proxyPort         {Proxy port [integer number]}
       sslCaCertPath     {Full path to SSL certificates [character string]}
       sslClientCertPath {Full path to client SSL certificates [character string]}
       sslIgnoreErrors   {Ignore SSL authorization errors [integer number: 0=no,2=yes]}

    General Panel keys:
       logFile          {Logfile, full path [character string]}
       rnxAppend        {Append files [integer number: 0=no,2=yes]}
       onTheFlyInterval {Configuration reload interval [character string: no|1 day|1 hour|5 min|1 min]}
       autoStart        {Auto start [integer number: 0=no,2=yes]}
       rawOutFile       {Raw output file, full path [character string]}

    RINEX Observations Panel keys:
       rnxPath        {Directory for RINEX files [character string]}
       rnxIntr        {File interval [character string: 1 min|2 min|5 min|10 min|15 min|30 min|1 hour|1 day]}
       rnxSampl       {File sampling rate [character string: 0.1 sec|1 sec|5 sec|10 sec|15 sec|30 sec|60 sec]}
       rnxSkel        {RINEX skeleton file extension [character string: skl|SKL]}
       rnxSkelPath    {Directory for local skeleton files [character string]}
       rnxOnlyWithSKL {Using RINEX skeleton file is mandatory [integer number: 0=no,2=yes]}
       rnxScript      {File upload script, full path [character string]}
       rnxVersion     {Specifies the RINEX version of the file contents [integer number: 2|3|4]}
       rnxV2Priority  {Priority of signal attributes for RINEX version 2 [character string, list separated by blank character,
                       example: G:12&PWCSLX G:5&IQX R:12&PC R:3&IQX R:46&ABX E:16&BCXZ E:578&IQX J:1&SLXCZ J:26&SLX J:5&IQX C:267&IQX C:18&DPX I:ABCX S:1&C S:5&IQX]}

    RINEX Ephemeris Panel keys:
       ephPath        {Directory [character string]}
       ephIntr        {File interval [character string: 1 min|2 min|5 min|10 min|15 min|30 min|1 hour|1 day]}
       ephOutPort     {Output port [integer number]}
       ephVersion     {Specifies the RINEX version of the file contents [integer number: 2|3|4]}

    RINEX Editing and QC Panel keys:
       reqcAction            {Action specification [character string:  Blank|Edit/Concatenate|Analyze]}
       reqcObsFile           {Input observations file(s), full path [character string, comma separated list in quotation marks]}
       reqcNavFile           {Input navigation file(s), full path [character string, comma separated list in quotation marks]}
       reqcOutObsFile        {Output observations file, full path [character string]}
       reqcOutNavFile        {Output navigation file, full path [character string]}
       reqcOutLogFile        {Output logfile, full path [character string]}
       reqcLogSummaryOnly    {Output only summary of logfile [integer number: 0=no,2=yes]}
       reqcSkyPlotSignals    {Observation signals [character string, list separated by blank character,
                              example: G:1&2&5 R:1&2&3 E:1&7 C:2&6 J:1&2 I:5&9 S:1&5]}
       reqcPlotDir           {QC plots directory [character string]}
       reqcRnxVersion        {RINEX version [integer number: 2|3|4]}
       reqcSampling          {RINEX output file sampling rate [character string: 0.1 sec|1 sec|5 sec|10 sec|15 sec|30 sec|60 sec]}
       reqcV2Priority        {Version 2 priority of signal attributes [character string, list separated by blank character,
                              example: G:12&PWCSLX G:5&IQX R:12&PC R:3&IQX R:46&ABX E:16&BCXZ E:578&IQX J:1&SLXCZ J:26&SLX J:5&IQX C:267&IQX C:18&DPX I:ABCX S:1&C S:5&IQX]}
       reqcStartDateTime     {Start time [character string, example: 1967-11-02T00:00:00]}
       reqcEndDateTime       {Stop time [character string, example: 2099-01-01T00:00:00]}
       reqcRunBy             {Operators name [character string]}
       reqcUseObsTypes       {Use observation types [character string, list separated by blank character, example: G:C1C G:L1C R:C1C RC1P]}
       reqcComment           {Additional comments [character string]}
       reqcOldMarkerName     {Old marker name [character string]}
       reqcNewMarkerName     {New marker name [character string]}
       reqcOldAntennaName    {Old antenna name [character string]}
       reqcNewAntennaName    {New antenna name [character string]}
       reqcOldAntennaNumber  {Old antenna number [character string]}
       reqcNewAntennaNumber  {New antenna number [character string]}
       reqcOldAntennadN      {Old north eccentricity [character string]}
       reqcNewAntennadN      {New north eccentricity [character string]}
       reqcOldAntennadE      {Old east eccentricity [character string]}
       reqcNewAntennadE      {New east eccentricity [character string]}
       reqcOldAntennadU      {Old up eccentricity [character string]}
       reqcNewAntennadU      {New up eccentricity [character string]}
       reqcOldReceiverName   {Old receiver name [character string]}
       reqcNewReceiverName   {New receiver name [character string]}
       reqcOldReceiverNumber {Old receiver number [character string]}
       reqcNewReceiverNumber {New receiver number [character string]}

    SP3 Comparison Panel keys:
       sp3CompFile       {SP3 input files, full path [character string, comma separated list in quotation marks]}
       sp3CompExclude    {Satellite exclusion list [character string, comma separated list in quotation marks, example: G04,G31,R]}
       sp3CompOutLogFile {Output logfile, full path [character string]}
       sp3SummaryOnly    {Output only summary of logfile [integer number: 0=no,2=yes]}

    Broadcast Corrections Panel keys:
       corrPath {Directory for saving files in ASCII format [character string]}
       corrIntr {File interval [character string: 1 min|2 min|5 min|10 min|15 min|30 min|1 hour|1 day]}
       corrPort {Output port [integer number]}

    Feed Engine Panel keys:
       outPort  {Output port, synchronized [integer number]}
       outWait  {Wait for full observation epoch [integer number of seconds: 1-30]}
       outSampl {Sampling rate [character string: 0.1 sec|1 sec|5 sec|10 sec|15 sec|30 sec|60 sec]}
       outFile  {Output file, full path [character string]}
       outUPort {Output port, unsynchronized [integer number]}

    Serial Output Panel:
       serialMountPoint         {Mountpoint [character string]}
       serialPortName           {Port name [character string]}
       serialBaudRate           {Baud rate [integer number: 110|300|600|1200|2400|4800|9600|19200|38400|57600|115200]}
       serialFlowControl        {Flow control [character string: OFF|XONXOFF|HARDWARE}
       serialDataBits           {Data bits [integer number: 5|6|7|8]}
       serialParity             {Parity [character string: NONE|ODD|EVEN|SPACE]}
       serialStopBits           {Stop bits [integer number: 1|2]}
       serialAutoNMEA           {NMEA specification [character string: no|Auto|Manual GPGGA|Manual GNGGA]}
       serialFileNMEA           {NMEA filename, full path [character string]}
       serialHeightNMEA         {Height [floating-point number]}
       serialHeightNMEASampling {Sampling rate [integer number of seconds: 0|10|20|30|...|280|290|300]}

    Outages Panel keys:
       adviseObsRate {Stream observation rate [character string: 0.1 Hz|0.2 Hz|0.5 Hz|1 Hz|5 Hz]}
       adviseFail    {Failure threshold [integer number of minutes: 0-60]}
       adviseReco    {Recovery threshold [integer number of minutes: 0-60]}
       adviseScript  {Advisory script, full path [character string]}

    Miscellaneous Panel keys:
       miscMount    {Mountpoint [character string]}
       miscIntr     {Interval for logging latency [character string: Blank|2 sec|10 sec|1 min|5 min|15 min|1 hour|6 hours|1 day]}
       miscScanRTCM {Scan for RTCM message numbers [integer number: 0=no,2=yes]}
       miscPort     {Output port [integer number]}

    PPP Client Panel 1 keys:
       PPP/dataSource  {Data source [character string: Blank|Real-Time Streams|RINEX Files]}
       PPP/rinexObs    {RINEX observation file, full path [character string]}
       PPP/rinexNav    {RINEX navigation file, full path [character string]}
       PPP/corrMount   {Corrections mountpoint [character string]}
       PPP/corrFile    {Corrections file, full path [character string]}
       PPP/crdFile     {Coordinates file, full path [character string]}
       PPP/logPath     {Directory for PPP log files [character string]}
       PPP/antexFile   {ANTEX file, full path [character string]}
       PPP/blqFile     {BLQ file, full path [character string]}
       PPP/ionoMount   {VTEC mountpoint, [char string]}
       PPP/ionoFile    {VTEC file, full path [char string]}
       PPP/nmeaPath    {Directory for NMEA output files [character string]}
       PPP/snxtroPath  {Directory for SINEX troposphere output files [character string]}
       PPP/snxtroIntr  {SINEX troposphere file interval [character string: 1 min|2 min|5 min|10 min|15 min|30 min|1 hour|1 day]}
       PPP/snxtroSampl {SINEX troposphere file sampling rate [character string: 1 sec|5 sec|10 sec|30 sec|60 sec|300 sec]}
       PPP/snxtroAc    {SINEX troposphere Analysis Center [3-char string]}
       PPP/snxtroSol   {SINEX troposphere solution ID [1-char]}

    PPP Client Panel 2 keys:
       PPP/lcGPS        {Select observations from GPS code and/or phase data [character string;     Pi&Li|Pi|Li|no]}
       PPP/lcGLONASS    {Select observations from GLONASS code and/or phase data [character string: Pi&Li|Pi|Li|no]}
       PPP/lcGalileo    {Select observations from Galileo code and/or phase data [character string: Pi&Li|Pi|Li|no]}
       PPP/lcBDS        {Select observations from BDS code and/or phase data [character string:     Pi&Li|Pi|Li|no]}
       PPP/modelObs     {select observation model [character string: Uncombined PPP|Ionosphere-free PPP|DCM with Code Biases|DCM with Phase Biases]}
       PPP/sigmaC1      {Sigma for code observations in meters [floating-point number]}
       PPP/sigmaL1      {Sigma for phase observations in meters [floating-point number]}
       PPP/maxResC1     {Maximal residuum for code observations in meters [floating-point number]}
       PPP/maxResL1     {Maximal residuum for phase observations in meters [floating-point number]}
       PPP/eleWgtCode   {Elevation dependent waiting of code observations [integer number: 0=no,2=yes]}
       PPP/eleWgtPhase  {Elevation dependent waiting of phase observations [integer number: 0=no,2=yes]}
       PPP/minObs       {Minimum number of observations [integer number: 4|5|6]}
       PPP/minEle       {Minimum satellite elevation in degrees [integer number: 0-20]}
       PPP/corrWaitTime {Wait for clock corrections [integer number of seconds: 0-20]}
       PPP/seedingTime  {Seeding time span for Quick Start [integer number of seconds]}
       PPP/pseudoOb     {Select pseudo observations [character string: no|Ionosphere]}
       PPP/sigmaGIM     {Sigma for GIM pseudo observations in meters [floating-point number]}
       PPP/maxResGIM    {Maximal residuum for GIM pseudo observations in meters [floating-point number]}

    PPP Client Panel 3 keys:
       PPP/staTable {Station specifications table [character string, semicolon separated list, each element in quotaion marks, example:
                    "WTZR00DEU0,100.0,100.0,100.0,100.0,100.0,100.0,0.1,3e-6,0,G:12&CWPSLX R:12&CP E:1&CBX E:5&QIX C:26&IQX;
                    FFMJ00DEU0,100.0,100.0,100.0,100.0,100.0,100.0,0.1,3e-6,0,G:12&CWPSLX R:12&CP E:1&CBX E:5&QIX C:26&IQX"]}

    PPP Client Panel 4 keys:
       PPP/plotCoordinates  {Mountpoint for time series plot [character string]}
       PPP/audioResponse    {Audio response threshold in meters [floating-point number]}
       PPP/mapWinDotSize    {Size of dots on map [integer number: 0-10]}
       PPP/mapWinDotColor   {Color of dots and cross hair on map [character string: red|yellow]}
       PPP/mapSpeedSlider   {Off-line processing speed for mapping [integer number: 1-100]}

    Combine Corrections Panel keys:
       cmbStreams      {Correction streams table [character string, semicolon separated list, each element in quotation marks, example:
                       "SSRA00ESA0 ESA 1.0;SSRA00BKG BKG 1.0"]}
       cmbMethodFilter {Combination approach [character string: Single-Epoch|Filter]}
       cmbBsxFile      {SINEX Bias file, full path [char string]}
       cmbMaxres       {Clock outlier residuum threshold in meters [floating-point number]
       cmbSampl        {Clock sampling rate [integer number of seconds: 0|10|20|30|40|50|60]}
       cmbGps          {GPS correction usage [integer number: 0=no,2=yes]}
       cmbGlo          {GLONASS correction usage [integer number: 0=no,2=yes]}
       cmbGal          {Galileo correction usage [integer number: 0=no,2=yes]}
       cmbBds          {Beidou correction usage [integer number: 0=no,2=yes]}
       cmbQzss         {QZSS correction usage [integer number: 0=no,2=yes]}
       cmbSbas         {SBAS correction usage [integer number: 0=no,2=yes]}
       cmbIrnss        {IRNSS correction usage [integer number: 0=no,2=yes]}

    Upload Corrections Panel keys:
       uploadMountpointsOut   {Upload corrections table [character string, semicolon separated list, each element in quotation marks, example:
                              "products.igs-ip.net,2101,SSRA02IGS1,2,usr,pass,IGS20,IGS-SSR,0,/home/user/BKG0MGXRTS${V3PROD}.SP3,/home/user/BKG0MGXRTS${V3PROD}.CLK,/home/user/BKG0MGXRTS${V3PROD}.BIA,258,1,0;
                              euref-ip.net,2101,SSRA02IGS1_EUREF,2,usr,pass,ETRF2000,RTCM-SSR,0,,,,258,2,0"]}
       uploadIntr             {Length of SP3, Clock RINEX and Bias SINEX file interval [character string: 1 min|2 min|5 min|10 min|15 min|30 min|1 hour|1 day]}
       uploadSamplRtcmEphCorr {Orbit corrections stream sampling rate [integer number of seconds: 0|5|10|15|20|25|30|35|40|45|50|55|60]}
       uploadSamplSp3         {SP3 file sampling rate [integer number of seconds: 0 sec|30 sec|60 sec|300 sec|900 sec]}
       uploadSamplClkRnx      {Clock RINEX file sampling rate [integer number of seconds: 0|5|10|15|20|25|30|35|40|45|50|55|60]}
       uploadSamplBiaSnx      {SINEX Bias file sampling rate [integer number of seconds: 0|5|10|15|20|25|30|35|40|45|50|55|60]}

    Custom Trafo keys:
       trafo_dx  {Translation X in meters [floating-point number]
       trafo_dy  {Translation Y in meters [floating-point number]
       trafo_dz  {Translation Z in meters [floating-point number]
       trafo_dxr {Translation change X in meters per year [floating-point number]
       trafo_dyr {Translation change Y in meters per year [floating-point number]
       trafo_dzr {Translation change Z in meters per year [floating-point number]
       trafo_ox  {Rotation X in arcsec [floating-point number]}
       trafo_oy  {Rotation Y in arcsec [floating-point number]}
       trafo_oz  {Rotation Z in arcsec [floating-point number]}
       trafo_oxr {Rotation change X in arcsec per year [floating-point number]}
       trafo_oyr {Rotation change Y in arcsec per year [floating-point number]}
       trafo_ozr {Rotation change Z in arcsec per year [floating-point number]}
       trafo_sc  {Scale [10^-9, floating-point number]}
       trafo_scr {Scale change [10^-9 per year, floating-point number]}
       trafo_t0  {Reference year [integer number]}

    Upload Ephemeris Panel keys:
       uploadEphMountpointsOut {Upload corrections table [character string, semicolon separated list, each element in quotation marks, example:
                               "products.igs-ip.net,443,BCEP00BKG0,2s,usr,pass,ALL;products.igs-ip.net,443,BCEP01BKG0,2s,usr,pass,G"]}
       uploadSamplRtcmEph      {Stream upload sampling rate [integer number of seconds: 0|5|10|15|20|25|30|35|40|45|50|55|60]}

    Add Stream keys:
       mountPoints   {Mountpoints [character string, semicolon separated list, example:
                     "//user:pass@igs-ip.net:2101/FFMJ00DEU0 RTCM_3.3 DEU 50.09 8.66 no 2;//user:pass@mgex.igs-ip.net:2101/CUT000AUS0 RTCM_3.0 ETH 9.03 38.74 no 2"}
       ntripVersion  {Ntrip Version [character string: 1|2|2s|R|U]}
       casterUrlList {Visited Broadcasters [character string, comma separated list]}

    Appearance keys:
       startTab  {Index of top panel to be presented at start time [integer number: 0-17]}
       statusTab {Index of bottom panel to be presented at start time [integer number: 0-3]}
       font      {Font specification [character string in quotation marks, example: "Helvetica,14,-1,5,50,0,0,0,0,0"]}

    Note:
    The syntax of some command line configuration options slightly differs from that
    used in configuration files: Configuration file options which contain one or more blank
    characters or contain a semicolon separated parameter list must be enclosed by quotation
    marks when specified on command line.

    Examples command lines:
    (1) /home/weber/bin/bnc
    (2) /Applications/bnc.app/Contents/MacOS/bnc
    (3) /home/userName/bin/bnc --conf /home/userName/MyConfigFile.bnc
    (4) bnc --conf /Users/userName/.config/BKG/BNC.bnc -nw
    (5) bnc --conf /dev/null --key startTab 4 --key reqcAction Edit/Concatenate --key reqcObsFile BRUX00BEL_S_20211251100_15M_01S_MO.rnx --key reqcOutObsFile BRUX00BEL_S_20211251100_15M_01S_MO_OUT.rnx --key reqcRnxVersion 2 --key reqcSampling "30 sec" --key reqcV2Priority "G:12&PWCSLX G:5&IQX"
    (6) bnc --conf /dev/null --key mountPoints "//user:pass@mgex.igs-ip.net:2101/CUT000AUS0 RTCM_3.0 ETH 9.03 38.74 no 2;//user:pass@igs-ip.net:2101/FFMJ00DEU1 RTCM_3.1 DEU 50.09 8.66 no 2"
    (7) bnc --conf /dev/null --key startTab 15 --key cmbStreams "SSRA00BKG1 BKG 1.0;SSRA00CNE1 CNES 1.0"
    (8) bnc --conf /dev/null --key startTab 16 --key uploadMountpointsOut "products.igs-ip.net,2101,SSRC00BKG1,2,usr,pass,IGS20,RTCM-SSR,2,/Users/userName/BKG0MGXRTS${V3PROD}.SP3,,,33,3,2;euref-ip.net,443,SSRA00BKG1_EUREF,2s,usr,pass,ETRF2000,IGS-SSR,0,,,,33,5,5"
    (9) bnc --conf /dev/null --key startTab 13 --key PPP/dataSource "Real-Time Streams" --key PPP/staTable "FFMJ00DEU1,100.0,100.0,100.0,100.0,100.0,100.0,0.1,3e-6,7777,G:12&CWPSLX R:12&CP E:1&CBX E:5&QIX C:26&IQX;CUT000AUS0,100.0,100.0,100.0,100.0,100.0,100.0,0.1,3e-6,7778,G:12&CWPSLX R:12&CP E:1&CBX E:5&QIX C:26&IQX"

#### 3.3 Further Reading Links:

Ntrip | https://igs.bkg.bund.de/ntrip/index
IGS Real-Rime Service (RTS) | https://igs.org/rts/
Ntrip Broadcaster overview | https://rtcm-ntrip.org/home
Ntrip Open Source software code | https://software.rtcm-ntrip.org
Radio Technical Commission for Maritime Services | https://www.rtcm.org/

Publications:

Caissy, M., L. Agrotis, G. Weber, M. Hernandez-Pajares and U. Hugentobler (2012) | The International GNSS Real-Time Service. GPS World, June 1, 2012.
Estey, L. H. and C. M. Meertens (1999) | TEQC: The Multi-Purpose Toolkit for GPS/GLONASS Data. GPS Solutions, Vol. 3, No. 1, pp. 42-49, 1999.
Huisman, L., P. Teunissen and C. Hu (2012) | GNSS Precise Point Positioning in Regional Reference Frames Using Real-time Broadcast Corrections. Journal of Applied Geodesy, Vol. 6, pp15-23, 2012.
Mervart, L., Z. Lukes, C. Rocken and T. Iwabuchi (2008) | Precise Point Positioning With Ambiguity Resolution in Real-Time. ION GNSS 2008.
RTCM SC-104 (2011) | Amendment 1 to RTCM Standard 10410.1 Networked Transport of RTCM via Internet Protocol (Ntrip) - Version 2.0. RTCM Papter 139-2011-SC104-STD, 2011.
Rupprecht, W. (2000) | DGPS-IP. http://www.wsrcc.com/wolfgang/gps/dgps-ip.html, 2000.
Stürze, A., L. Mervart, W. Söhne, G. Weber, G. Wübbena (2012) | Real-Time PPP using open CORS Networks and RTCM Standards. 3rd International Conference on Machine Control & Guidance, March 27-29, 2012
Weber, G., D. Dettmering and H. Gebhard (2005a) | Networked Transport of RTCM via Internet Protocol (NTRIP). In: Sanso F. (Ed.): A Window on the Future, Proceedings of the IAG General Assembly, Sapporo, Japan, 2003, Springer Verlag, Symposia Series, Vol. 128, p. 60-64, 2005.
Weber, G., D. Dettmering, H. Gebhard and R. Kalafus (2005b) | Networked Transport of RTCM via Internet Protocol (Ntrip), IP-Streaming for Real-Time GNSS Applications. ION GNSS 2005.
Weber, G., and M. Honkala (2004) | The future is talking Ntrip. Newsletter, Trimble GmbH Raunheim, Germany, 2004.
Weber, G. and L. Mervart (2009) | The BKG Ntrip Client (BNC), Report on EUREF Symposium 2007 in London. Mitteilungen des Bundesamtes fuer Kartographie und Geodaesie, Band 42, Frankfurt, 2009.
Weber, G. and L. Mervart (2010) | Real-time Combination of GNSS Orbit and Clock Correction Streams Using a Kalman Filter Approach. ION GNSS 2010.
Weber, G, L. Mervart, Z. Lukes, C. Rocken and J. Dousa (2007) | Real-time Clock and Orbit Corrections for Improved Point Positioning via Ntrip. ION GNSS 2007.
Weber, G., L. Mervart, A. Stürze, A. Rülke and D. Stöcker (2016) | BKG Ntrip Client, Version 2.12. Mitteilungen des Bundesamtes für Kartographie und Geodäsie, Vol. 49, Frankfurt am Main, 2016.

#### 3.4 Abbreviations

AC | Analysis Center
AFREF | IAG Reference Frame Sub-Commission for Africa
ANTEX | Antenna Exchange Format
APC | Antenna Phase Center
APREF | IAG Reference Frame Sub-Commission for Asia and Pacific
ARP | Antenna Reference Point
BKG | Bundesamt für Kartographie und Geodäsie
BNC | BNK Ntrip Client
BSW | Bernese GNSS Software
CC | Combination Center
CLI | Command Line Interface
CoM | Center Of Mass
DGNSS | Differential GNSS
DGPS-IP | Differential GPS via Internet Protocol
DMG | Disk Image, File
DREF91 | Geodetic Datum for Germany 1991
ECEF | Earth-Centred-Earth-Fixed
EDGE | Enhanced Data Rates for GSM Evolution
ETRF2000 | European Terrestrial Reference Frame 2000
EUREF | IAG Reference Frame Sub-Commission for Europe
EoE | End of Epoch
FKP | Flächen-Korrektur-Parameter
FTP | File Transfer Protocol
GDA2020 | Geodetic Datum Australia 2020
GNSS | Global Navigation Satellite System
GNU | GNU's Not Unix
GPL | General Public License
GPRS | General Packet Radio Service
GPSWD | GPS Week and Day
GSM | Global System for Mobile Communications
GUI | Graphical User Interface
HP MSM | High Precision Multiple Signal Messages
HR URA | High Rate User Range Accuracy
HTTP | Hypertext Transfer Protocol
HTTPS | Hypertext Transfer Protocol Secure
IAG | International Association of Geodesy
ICECAST | Streaming Media Server
IGS20 | IGS Reference Frame 2020
IGS | International GNSS Service
IOD | Issue of Data
IP | Internet Protocol
ITRF2020 | International Terrestrial Reference Frame 2020
L3 | Ionosphere-Free Linear Combination Of Phase Observations
LAN | Local Area Network
LC | Linea Combination
M-GEX | Multi GNSS-Experiment
MAC | Master Auxiliary Concept
MJD | Modified Julian Date
MSI | Microsoft Installer, File
MSM | Multiple Signal Messages
MW | Melbourne Wübbena Linear Combination
NAD83 | North American Datum 1983
NAREF | IAG Reference Frame Sub-Commission for North America
NMEA | National Marine Electronics Association Format
Ntrip | Networked Transport of RTCM via Internet Protocol
OSM | OpenStreetMap
OSR | Observation Space Representation
PDOP | Positional Dilution Of Precision
PNG | Portable Network Graphics
PPP | Precise Point Positioning
Qt | Cross-Platform Application Framework
REQC | RINEX Editing and Quality Checking
RINEX | Receiver Independent Exchange Format
RTCM SC-104 | Radio Technical Commission for Maritime Services, Special Committee 104
RTK | Real Time Kinematic
RTKPLOT | View and Plot Positioning Solutions Software, Part of RTKLIB
RTNET | Real-Time Network Format
RTP | Real-Time Transport Protocol
RTSP | Real-Time Streaming Protocol
SBAS | Space Based Augmentation System
SINEX TRO | Troposphere Solution Independent Exchange Format
SINEX | Solution Independent Exchange Format
SIRGAS2000 | Geodetic Datum for Latin America and Caribbean 2000
SIRGAS | IAG Reference Frame Sub-Commission for Latin America and Caribbean
SP3 | Standard Product # 3
SPP | Single Point Positioning
SSL | Secure Sockets Layer
SSR | State Space Representation
SVN | Subversion, Revision Control System
TCP | Transmission Control Protocol
TEQC | Translation, Editing and Quality Checking
TLS | Transport Layer Security
UDP | User Datagram Protocol
UMTS | Universal Mobile Telecommunications System
URA | User Range Accuracy
VRS | Virtual Reference Station
VTEC | Vertical Total Electron Content