Changeset 366 in ntrip for trunk/BNC/bnchelp.html
- Timestamp:
- Jan 17, 2007, 4:17:20 PM (18 years ago)
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trunk/BNC/bnchelp.html
r360 r366 60 60 B - 5.5. <a href=#rnxskeleton>RINEX Skeleton Extension</a><br> 61 61 B - 5.6. <a href=#rnxappend>Append Files</a><br> 62 B - 5.7. <a href=#approxlatlon>Approx. Lat./Lon.</a><br>63 62 B - 6. <a href=#mountpoints>Mountpoints</a><br> 64 63 B - 6.1. <a href=#AddMounts>Add Mountpoints</a><br> … … 119 118 <p> 120 119 BNC lets you output synchronized observations epoch by epoch. This output is made available in a plain ASCII format and in a binary format. The output comprises the following observations if available:</p> 121 StatID, SVPRN, GPSWeek, GPSWeeks, C1, P1, P2, L1, L2, SNR1, SNR2. 120 StatID, SVPRN, GPSWeek, GPSWeeks, C1, C2, P1, P2, L1, L2, SNR1, SNR2. 122 121 </p> 123 122 <p> … … 164 163 int GPSWeek; // Week of GPS-Time 165 164 double GPSWeeks; // Second of Week (GPS-Time) 166 double C1; // CA-code pseudorange (meters) 165 double C1; // C1-code pseudorange (meters) 166 double C2; // C2-code pseudorange (meters) 167 167 double P1; // P1-code pseudorange (meters) 168 168 double P2; // P2-code pseudorange (meters) … … 176 176 <p><a name="rinex"><h4>B - 5. RINEX</h4></p> 177 177 <p> 178 Observations are converted to RINEX Version 2.1. RINEX file names are derived by BNC from the first 4 characters of the corresponding mountpoint (4Char Station ID) while omitting the residual part of the mountpoint string. Thus, retrieving data from mountpoints FRANKFURT and WETTZELL leads to hourly RINEX observation files named</p> 178 Observations are converted to RINEX Version 2.11. RINEX file names are derived by BNC from the first 4 characters of the corresponding mountpoint (4Char Station ID) while omitting the residual part of the mountpoint string. Thus, retrieving data from mountpoints FRANKFURT and WETTZELL leads to hourly RINEX observation files named</p> 179 179 <p> 180 180 FRAN{ddd}{h}.{yy}O<br> … … 205 205 </p> 206 206 <p> 207 BNC's RINEX observation files generally contain C1, P1, P2, L1, and L2observations. In case an observation is unavailable, its value is set to zero '0.000'. Note that even if a RINEX file does not contain GLONASS data, the 'RINEX TYPE' field in the RINEX file header may be set to 'M (MIXED)'.207 BNC's RINEX observation files generally contain C1, C2, P1, P2, L1, L2, SNR1, and SNR3 observations. In case an observation is unavailable, its value is set to zero '0.000'. Note that even if a RINEX file does not contain GLONASS data, the 'RINEX TYPE' field in the RINEX file header may be set to 'M (MIXED)'. 208 208 </p> 209 209 … … 283 283 When starting BNC, new RINEX files are created by default. Probably existing files will be overwritten. However, it may be desirable to append observations to already existing RINEX files following a restart of BNC after an intentional 'Stop', a system crash or a crash of BNC. Hit 'Append files' to continue with already existing files and thus save what has been recorded so far. Note that the option 'Append files' also concerns the 'ASCII output file' and the 'Log' file. 284 284 </p> 285 286 <p><a name="approxlatlon"><h4>B - 5.7 Approx. Lat./Lon. - mandatory for Virtual Reference Stations (VRS)</h4></p>287 <p>288 BNC allows to retrieve streams from Virtual Reference Stations (VRS). For that an approximate rover position needs to be send in NMEA format to a VRS supporting NTRIP broadcaster. In return, an individual user-specific data stream is generated by a network RTK software. This stream is tailored exactly to the 'Approx. Lat./Lon.' you enter. The approximate position has to be introduced in northern latitude degrees (example for northern hemisphere: 52.436, example for eastern hemisphere: -24.567) and eastern longitude degrees (example: 358.872 or -1.128).289 </p>290 <p>291 Introducing an 'Approx. Lat./Lon.' is only necessary when retrieving a VRS stream. The approximate position must point to a location within the service area of the affected RTK network. Note that VRS streams that require an 'Approx. Lat./Lon.' are marked by the integer '1' in data field 'nmea' of the affected NTRIP broadcaster source-table. Note further that when working in a Local Area Network (LAN), NMEA messages may be blocked by a proxy server, firewall or virus scanner.292 </p>293 294 285 <p><a name="mountpoints"><h4>B - 6. Mountpoints</h4></p> 295 286 <p> 296 287 Each stream on an NTRIP broadcaster is defined through a unique source ID called mountpoint. An NTRIP client like BNC can access the data of a desired stream by its mountpoint. Information about mountpoints is available through the source-table maintained by the NTRIP broadcaster. Note that mountpoints could show up in BNC more than once when retrieving streams from several NTRIP broadcasters. 297 </p> 288 </p> 289 290 Streams selected for retrieval are listed in the 'Mountpoints' section on BNC's main window. The list provides the following information extracted from NTRIP broadcaster source-tables: 291 292 <table> 293 <tr></tr> 294 <tr><td>'mountpoint' </td><td>NTRIP broadcaster URL, port, and mountpoint.</td></tr> 295 <tr><td>'decoder' </td><td>Internal decoder used to handle the incoming stream content according to its format; editable.</td></tr> 296 <tr><td>'lat' </td><td>Latitude of reference station, degrees, north; editable for VRS streams.</td></tr> 297 <tr><td>'long' </td><td>Longitude of reference station, degrees, east; editable for VRS streams.</td></tr> 298 <tr><td>'type' </td><td>Mountpoint refers to physical Reference Station (RS) or Virtual Reference Station (VRS).</td></tr> 299 <tr><td>'bytes' </td><td>Number of bytes retrieved. 300 </table> 298 301 299 302 <p><a name="AddMounts"><h4>B - 6.1 Add Mountpoints</h4></p> … … 325 328 326 329 <p><a name="edit"><h4>B - 6.6 Edit Mountpoints</h4></p> 327 <p> 328 BNC automatically selects one out of several incorporated decoders for a stream based on its 'format' and 'format-details' as given in the source-table. It may happen that you need to overrule the automated decoder selection because of source-table setup deficiencies. Therefore BNC allows to edit (double-click) the decoder string for each stream shown under 'Mountpoints'. Accepted decoder strings allowed to be introduced are 'RTCM_2.x', 'RTCM_3', and 'RTIGS'. 329 </p> 330 <ul> 331 <li> 332 BNC automatically selects one out of several internal decoders for a stream based on its 'format' and 'format-details' as given in the source-table. It may happen that you need to overrule the automated decoder selection because of source-table setup deficiencies. Therefore BNC allows to edit the decoder string (first double-click, then edit field 'decoder', then hit Enter) for the streams shown under 'Mountpoints'. Accepted decoder strings allowed to be introduced are 'RTCM_2.x', 'RTCM_3', and 'RTIGS'. 333 </li> 334 <li> 335 BNC allows to retrieve streams from Virtual Reference Stations. Whether a stream comes from a physical Reference Station (RS) or a Virtual Reference Station (VRS) is indicated in column 'type' under 'Mountpoints' as well as in column 'type' of the affected source-table. For retrieving a VRS stream, an approximate rover position is required to be send in NMEA format to the NTRIP broadcaster. In return, an individual user-specific data stream is generated, usually by a network RTK software. This stream is tailored exactly to the latitude and longitude shown in the 'lat' and 'long' columns under 'Mountpoints'. Default values for 'lat' and 'long' are taken from the source-table. You may change these values (first double-click, then edit fields 'lat' and/or 'long', then hit Enter) according to your needs. The position has to be introduced in northern latitude degrees (example for northern hemisphere: 52.436, example for eastern hemisphere: -24.567) and eastern longitude degrees (example: 358.872 or -1.128). Editing the 'lat' and 'long' values under 'Mountpoints' is only possible for VRS streams. The position must point to a location within the service area of the affected RTK network. Note that when running BNC in a Local Area Network (LAN), NMEA strings may be blocked by a proxy server, firewall or virus scanner. 336 </li> 337 </ul> 330 338 331 339 <p><a name="log"><h4>B - 7. Log - optional</h4></p> … … 358 366 </li> 359 367 <li> 360 So far BNC only handles GPS and GLONASS data while ignoring Galileo. Furthermore, its function is limited today to processing C1, P1, P2, L1, and L2 observations only.361 </li> 362 <li> 363 Due to a limitation of the RTIGS format and transport protocol, streams coming in that format can only contain GPS data.368 So far BNC only handles GPS and GLONASS data while ignoring Galileo. 369 </li> 370 <li> 371 BNC's function is limited today to processing C1, C2, P1, P2, L1, L2, SNR1, and SNR2 observations. Which observables become available through a specific stream depends on the setup of the affected receiver and the applied data format. Note that RTCM Version 2.x streams can not transport signal-to-noise ratios (SNR) and RTCM Version 3 streams can only transport one code observable per frequency. Note further that signal-to-noise ratios SNR1 and SNR2 are mapped to integer numbers 1 to 9. 364 372 </li> 365 373 <li> … … 367 375 </li> 368 376 <li> 369 If the ambiguity field is not set in RTCM Version 3 streams, the BNC output will be no valid RINEX. All values will be stored modulo 299792.458. A COMMENT line will tell you, when this happens. It would be necessary to approximately calculate the range to fix the ambiguity (needing ephemeris/almanac and easy positioning algorithm). 377 If the ambiguity field is not set in RTCM Version 3 streams (i.e. when sending message type 1003 but no 1004), the BNC output will be no valid RINEX. All values will be stored modulo 299792.458. (It would be necessary to approximately calculate the range to fix the ambiguity, needing ephemeris/almanac and an easy positioning algorithm). 378 </li> 379 <li> 380 As a consequence of the current implementation of the RTIGS format and transport protocol, streams coming in that format contain only GPS data. 370 381 </li> 371 382 <li>
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