Changeset 6918 in ntrip for trunk/BNC/src/bnchelp.html


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Timestamp:
Jun 18, 2015, 10:44:21 AM (9 years ago)
Author:
weber
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Documentation completed

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  • trunk/BNC/src/bnchelp.html

    r6917 r6918  
    13311331<p><a name="correct"><h4>3.8. Broadcast Corrections</h4></p>
    13321332<p>
    1333 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 is using 'observation space' information. The representation with the RTCM standard can be called 'ObservationSpace Representation' (OSR).
     1333Differential 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 is using 'observation space' information. The representation with the RTCM standard can be called 'Observation Space Representation' (OSR).
    13341334</p>
    13351335<p>
    … …  
    13411341<li>Orbit corrections to Broadcast Ephemeris</li>
    13421342<li>Clock corrections to Broadcast Ephemeris</li>
    1343 <li>Code biases</li>
    13441343<li>Combined orbit and clock corrections to Broadcast Ephemeris</li>
    13451344<li>User Range Accuracy (URA)</li>
     1345<li>High Rate User Range Accuracy (HR URA)</li>
     1346<li>Code biases</li>
     1347<li>Phase biases</li>
    13461348<li>High-rate GPS clock corrections to Broadcast Ephemeris</li>
     1349<li>Vertical Total Electron Content (VTEC)</li>
    13471350</ul>
    13481351<p>
    … …  
    13621365
    13631366<p>
    1364 The orbit and clock corrections do not include local effects (like Ocean Loading or Solid Earth Tides) or atmospheric effects (Ionosphere and/or troposphere). Depending on the accuracy of your application you should correct for such effects by other means. There is currently no RTCM SSR message for ionospheric state parameters. Such messages are needed for accurate single frequency applications. The development of Iono messages will be the next step in the schedule of the RTCM State Space Representation Working Group.
    1365 </p>
    1366 
    1367 <p>
    1368 Broadcast Corrections can be saved by BNC in files. The file name convention for Broadcast Correction files follows the convention for RINEX files except for the last character of the file name suffix which is set to &quot;C&quot;.
    1369 </p>
    1370 
    1371 <p>
    1372 Saved files contain blocks of records in plain ASCII format where - separate for each GNSS, message type, stream, and epoch - the begin of a block is indicated by a line like (examples):
    1373 </p>
    1374 <p>
    1375 ! Orbits/Clocks: 30 GPS 0 Glonass CLK11<br>
    1376 or<br>
    1377 ! Orbits/Clocks: 0 GPS 19 Glonass CLK11
    1378 <p>
    1379 Such line informs you about the number of records (here 30 and 19) carrying GPS or GLONASS related parameters you should receive next.
    1380 </p>
    1381 <p>
    1382 The first five parameters in each Broadcast Corrections record are:
    1383 </p>
    1384 <p>
    1385 <ul>
    1386 <li>RTCM Version 3 message type number</li>
     1367The 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 correct for global ionospheric effects using so-call VTEC messages for global ionospheric state parameters.
     1368</p>
     1369
     1370<p>
     1371While we have a plain ASCII standard for saving broadcast ephemeris in RINEX Navigation files, we don't have an equivalent standard for corrections to broadcast ephemeris. Hence BNC saves Broadcast Corrections files following its own format definition. The file name convention for Broadcast Correction files follows the convention for RINEX Version 2 files except for the last character of the file name suffix which is set to &quot;C&quot;.
     1372</p>
     1373
     1374<p>
     1375Saved files contain blocks of records in plain ASCII format. The first record in each block contains the following 10 parameters:
     1376</p>
     1377<p>
     1378<ul>
     1379<li>SSR message type indicator:<br>ORBIT, CLOCK, CODE_BIAS, PHASE_BIAS, or VTEC</li>
     1380<li>Year, GPS time</li>
     1381<li>Month, GPS time</li>
     1382<li>Day, GPS time</li>
     1383<li>Hour, GPS time</li>
     1384<li>Minute, GPS time</li>
     1385<li>Second, GPS time</li>
    13871386<li>SSR message update interval indicator</li>
    13881387<ul>
    … …  
    14041403<li>15 = 10800 sec</li>
    14051404</ul>
    1406 <li>GPS Week</li>
    1407 <li>Second in GPS Week</li>
     1405<li>Number of following satellites (records) in this block</li>
     1406<li>Mountpoint, stream indicator</li>
     1407</ul>
     1408Each 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 &quot;0.000&quot;.
     1409<p>
     1410<b>Example for block 'ORBIT' carrying orbit corrections</b>
     1411</p>
     1412<pre>
     1413> ORBIT 2015 06 17 11 43 35.0 2 53 CLK93
     1414G01   9     0.5134     0.3692     0.6784        0.0000    -0.0000    -0.0000
     1415G02  25    57.6817   139.0492   -91.3456        0.5436    -0.6931     1.0173
     1416G03  79   -32.1768   191.8368  -121.6540        0.2695     0.2296     0.4879
     1417...
     1418G32  82     1.8174     1.1704     0.2200       -0.0002    -0.0000    -0.0001
     1419R01  59     0.7819    -0.6968     0.7388       -0.0001     0.0004     0.0004
     1420R02  59     0.5816    -0.5800    -0.2004        0.0001    -0.0006     0.0001
     1421R03  59     0.4635    -0.9104    -0.3832        0.0001     0.0001     0.0005
     1422...
     1423R24  59     0.5935     2.0732    -0.6884       -0.0000     0.0004     0.0003
     1424</pre>
     1425
     1426<p>
     1427The 'satellite records' in this block provide the following information:
     1428<ul>
    14081429<li>GNSS Indicator and Satellite Vehicle Pseudo Random Number</li>
    1409 </ul>
    1410 </p>
    1411 <p>
    1412 In case of RTCM message types 1057 or 1063 (see Annex) these parameters are followed by
    1413 </p>
    1414 <p>
    1415 <ul>
    14161430<li>IOD referring to Broadcast Ephemeris set</li>
    14171431<li>Radial Component of Orbit Correction to Broadcast Ephemeris [m]</li>
    … …  
    14211435<li>Velocity of Along-track Component of Orbit Correction to Broadcast Ephemeris [m/s]</li>
    14221436<li>Velocity of Cross-track Component of Orbit Correction to Broadcast Ephemeris [m/s]</li>
    1423 <p>
    1424 </ul>
    1425 </p>
    1426 <p>
    1427 Undefined parameters would be set to zero &quot;0.000&quot;.<br>Example:
    1428 <pre>
    1429 ...
    1430 1057 0 1686 283200.0 G02    21      1.062   -0.791    1.070     -0.00025   -0.00031   -0.00005
    1431 1057 0 1686 283200.0 G03    25      1.765   -2.438   -0.290     -0.00009   -0.00060    0.00028
    1432 1057 0 1686 283200.0 G04    14      1.311   -0.862    0.334      0.00005   -0.00038   -0.00015
    1433 
    1434 ...
    1435 1063 0 1686 283200.0 R01    39      0.347    1.976   -1.418      0.00048   -0.00091    0.00008
    1436 1063 0 1686 283200.0 R02    39      0.624   -2.092   -0.155      0.00005   -0.00054    0.00053
    1437 1063 0 1686 283200.0 R03    39      0.113    5.655   -1.540      0.00003   -0.00079   -0.00003
    1438 1063 0 1686 283200.0 R05    39      0.237    1.426   -1.282      0.00054   -0.00020    0.00027
    1439 ...
    1440 </pre>
    1441 <p>
     1437</ul>
     1438</p>
     1439
     1440<p>
     1441TBC<br>
    14421442In case of RTCM message types 1058 or 1064 (see Annex) the first five parameters in each record are followed by
    14431443</p>
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