Changeset 7709 in ntrip for trunk


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Timestamp:
Jan 24, 2016, 10:33:19 PM (4 years ago)
Author:
weber
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  • trunk/BNC/src/bnchelp.html

    r7708 r7709  
    1919To help justify funding the development of BNC,<sup>&nbsp;</sup>we kindly ask users to include a citation when applying the software results in a publication. We suggest:
    2020<br><br>
    21 Weber, G., L. Mervart, A. St&uuml;rze, A. R&uuml;lke and D. St&ouml;cker:<br>
     21Weber, G., L. Mervart, A. St&uuml;rze, A. R&uuml;lke and D. St&ouml;cker (2016):<br>
    2222&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; BKG Ntrip Client, Version 2.12. Mitteilungen des Bundesamtes<br>
    2323&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; f&uuml;r Kartographie und Geod&auml;sie, Vol. 49, Frankfurt am Main, 2016.
     
    10611061</p>
    10621062<p>
    1063 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 et al. 2004 & 2005) 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.
    1064 </p>
    1065 <p>
    1066 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. 2005). 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.
    1067 </p>
    1068 <p>
    1069 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 which 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. 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.
     1063To 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.
     1064</p>
     1065<p>
     1066For 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.
     1067</p>
     1068<p>
     1069With 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 which 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.
    10701070</p>
    10711071<p>
     
    28102810BNC can derive coordinates for rover positions following the Precise Point Positioning (PPP) approach. It uses code or code plus phase data from one or more GNSS systems in ionosphere-free linear combinations P3, L3, or P3&L3. Besides pulling streams of observations from dual frequency GNSS receiver, this also
    28112811<ul>
    2812 <li>Requires pulling in addition a stream carrying satellite orbit and clock corrections to Broadcast Ephemeris in the form of RTCM Version 3 'State Space Representation' (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 <u>http://igs.bkg.bund.de/ntrip/orbits</u>. Stream 'CLK11' on Ntrip Broadcaster 'products.igs-ip.net:2101' (Caissy et al. 2012) is an example.</li>
     2812<li>Requires pulling in addition a stream carrying satellite orbit and clock corrections to Broadcast Ephemeris in the form of RTCM Version 3 'State Space Representation' (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 <u>http://igs.bkg.bund.de/ntrip/orbits</u> (Caissy et al. 2012). Stream 'CLK11' on Ntrip Broadcaster 'products.igs-ip.net:2101' is an example.</li>
    28132813<li>May require pulling a stream carrying Broadcast Ephemeris available as RTCM Version 3 message types 1019, 1020, 1043, 1044, 1045, 1046 and 63 (tentative). 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 <u>http://igs.bkg.bund.de/ntrip/ephemeris</u>. Stream 'RTCM3EPH' on caster 'products.igs-ip.net:2101' is an example.</li>
    28142814</ul>
     
    33713371<p>
    33723372<p>
    3373 Specify on which ionosphere-free Linear Combinations (LCs) of observations you want to base ambiguity resolutions. This implicitly defines the kind of GNSS observations you want to use. The specification is to be done per GNSS system ('GPS LCs', 'GLONASS LCs', 'Galileo LCs', 'BDS LCs').
     3373Specify on which ionosphere-free Linear Combinations (LCs) of observations you want to base ambiguity resolutions (Mervart et al. 2008). This implicitly defines the kind of GNSS observations you want to use. The specification is to be done per GNSS system ('GPS LCs', 'GLONASS LCs', 'Galileo LCs', 'BDS LCs').
    33743374</p>
    33753375<p>
     
    35493549</p>
    35503550<p>
    3551 In view of IGS real-time products, the 'Combine Corrections' functionality has been integrated in BNC because
     3551In view of IGS real-time products, the 'Combine Corrections' functionality has been integrated in BNC (Weber and Mervart 2010) because
    35523552<ul>
    35533553<li>The software with its Graphic User Interface and wide range of supported Operating Systems represents a perfect platform to process many Broadcast Correction streams in parallel;</li>
     
    38063806</p>
    38073807<p>
    3808 From a theoretical point of view, this kind of approximation leads to inconsistencies between orbits and clocks and is therefore not allowed. 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. The Australian GDA94 transformation with its comparatively large scale parameter is an exception in this as discrepancies may reach up there to two centimeters.
     3808From 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. The Australian GDA94 transformation with its comparatively large scale parameter is an exception in this as discrepancies may reach up there to two centimeters.
    38093809</p>
    38103810
     
    51905190<tr><td><b>Publications</b></td></tr>
    51915191
    5192 <tr><td>Estey, Louis H. and Charles M. Meertens</td><td>TEQC: The Multi-Purpose Toolkit for GPS/GLONASS Data, GPS Solutions, Vol. 3, No. 1, pp. 42-49, 1999.</td></tr>
    5193 
    5194 <tr><td>Rupprecht, Wolfgang</td><td>DGPS-IP, <u>http://www.wsrcc.com/wolfgang/gps/dgps-ip.html</u>, 2000.</td></tr>
    5195 
    5196 <tr><td>Weber, G., and M. Honkala</td><td>The future is talking Ntrip. Newsletter, Trimble GmbH Raunheim, Germany, 2004.</td></tr>
    5197 
    5198 <tr><td>Weber, G., D. Dettmering and H. Gebhard</td><td>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.</td></tr>
    5199 
    5200 <tr><td>Weber, G., D. Dettmering, H. Gebhard and R. Kalafus </td><td>Networked Transport of RTCM via Internet Protocol (Ntrip), IP-Streaming for Real-Time GNSS Applications, ION GNSS 2005.</td></tr>
    5201 
    5202 <tr><td>Weber, G, L. Mervart, Z. Lukes, C. Rocken and J. Dousa </td><td>Real-time Clock and Orbit Corrections for Improved Point Positioning via Ntrip, ION GNSS 2007.</td></tr>
    5203 
    5204 <tr><td>Mervart, L., Z. Lukes, C. Rocken and T. Iwabuchi </td><td>Precise Point Positioning With Ambiguity Resolution in Real-Time, ION GNSS 2008.</td></tr>
    5205 
    5206 <tr><td>Weber, G. and L. Mervart </td><td>The BKG Ntrip Client (BNC), Report on EUREF Symposium 2007 in London, Mitteilungen des Bundesamtes fuer Kartographie und Geodaesie, Band 42, Frankfurt, 2009.</td></tr>
    5207 
    5208 <tr><td>Weber, G. and L. Mervart </td><td>Real-time Combination of GNSS Orbit and Clock Correction Streams Using a Kalman Filter Approach, ION GNSS 2010.</td></tr>
    5209 
    5210 <tr><td>RTCM SC-104</td><td>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.</td></tr>
    5211 
    5212 <tr><td>Caissy, M., L. Agrotis, G. Weber, M. Hernandez-Pajares and U. Hugentobler</td><td>The International GNSS Real-Time Service, GPS World, June 1, 2012.</td></tr>
    5213 
    5214 <tr><td>Huisman, L., P. Teunissen and C. Hu </td><td>GNSS Precise Point Positioning in Regional Reference Frames Using Real-time Broadcast Corrections, Journal of Applied Geodesy, Vol. 6, pp15-23, 2012.</td></tr>
    5215 
    5216 <tr><td>Mervart, L., A. St&uuml;rze, G. Weber, A. R&uuml;lke and D. St&ouml;cker</td><td>BKG Ntrip Client, Version 2.12 Mitteilungen des Bundesamtes f&uuml;r Kartographie und Geod&auml;sie, Vol. 49, Frankfurt am Main, 2016.</td><tr>
     5192<tr><td>Caissy, M., L. Agrotis, G. Weber, M. Hernandez-Pajares and U. Hugentobler (2012)</td><td>The International GNSS Real-Time Service, GPS World, June 1, 2012.</td></tr>
     5193
     5194<tr><td>Estey, L. H. and C. M. Meertens (1999)</td><td>TEQC: The Multi-Purpose Toolkit for GPS/GLONASS Data, GPS Solutions, Vol. 3, No. 1, pp. 42-49, 1999.</td></tr>
     5195
     5196<tr><td>Huisman, L., P. Teunissen and C. Hu (2012)</td><td>GNSS Precise Point Positioning in Regional Reference Frames Using Real-time Broadcast Corrections, Journal of Applied Geodesy, Vol. 6, pp15-23, 2012.</td></tr>
     5197
     5198<tr><td>Mervart, L., Z. Lukes, C. Rocken and T. Iwabuchi (2008)</td><td>Precise Point Positioning With Ambiguity Resolution in Real-Time, ION GNSS 2008.</td></tr>
     5199
     5200<tr><td>RTCM SC-104 (2011)</td><td>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.</td></tr>
     5201
     5202<tr><td>Rupprecht, W. (2000)</td><td>DGPS-IP, <u>http://www.wsrcc.com/wolfgang/gps/dgps-ip.html</u>, 2000.</td></tr>
     5203
     5204<tr><td>Weber, G., D. Dettmering and H. Gebhard (2005a)</td><td>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.</td></tr>
     5205
     5206<tr><td>Weber, G., D. Dettmering, H. Gebhard and R. Kalafus (2005b)</td><td>Networked Transport of RTCM via Internet Protocol (Ntrip), IP-Streaming for Real-Time GNSS Applications, ION GNSS 2005.</td></tr>
     5207
     5208<tr><td>Weber, G., and M. Honkala (2004)</td><td>The future is talking Ntrip. Newsletter, Trimble GmbH Raunheim, Germany, 2004.</td></tr>
     5209
     5210<tr><td>Weber, G. and L. Mervart (2009)</td><td>The BKG Ntrip Client (BNC), Report on EUREF Symposium 2007 in London, Mitteilungen des Bundesamtes fuer Kartographie und Geodaesie, Band 42, Frankfurt, 2009.</td></tr>
     5211
     5212<tr><td>Weber, G. and L. Mervart (2010)</td><td>Real-time Combination of GNSS Orbit and Clock Correction Streams Using a Kalman Filter Approach, ION GNSS 2010.</td></tr>
     5213
     5214<tr><td>Weber, G, L. Mervart, Z. Lukes, C. Rocken and J. Dousa (2007)</td><td>Real-time Clock and Orbit Corrections for Improved Point Positioning via Ntrip, ION GNSS 2007.</td></tr>
     5215
     5216<tr><td>Weber, G., L. Mervart, A. St&uuml;rze, A. R&uuml;lke and D. St&ouml;cker (2016)</td><td>BKG Ntrip Client, Version 2.12 Mitteilungen des Bundesamtes f&uuml;r Kartographie und Geod&auml;sie, Vol. 49, Frankfurt am Main, 2016.</td><tr>
    52175217
    52185218</table>
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