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- Oct 6, 2006, 5:11:19 PM (18 years ago)
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trunk/BNC/bnchelp.html
r212 r213 504 504 <p><h4>F - 3. RTIGS</h4></p> 505 505 <p> 506 Input from Ken? 506 RTIGS is a data format and transport protocol for GPS observable. It has been definde by the Real-Time IGS Working Group (RTIGS WG). Its definition is based on the SOC format. Every RTIGS record has one of the following numbers: 507 </p> 508 <p> 509 Station record number 100<br> 510 Observation record number 200<br> 511 Ephemeris record number 300<br> 512 Meteorological record number 400 513 </p> 514 <p> 515 Every station has one of the following unique numbers: 516 </p> 517 <p> 518 1-99 reserved for JPL<br> 519 100-199 reserved for NRCan<br> 520 200-299 reserved for NGS<br> 521 300-399 reserved for ESOC<br> 522 400-499 reserved for GFZ<br> 523 500-599 reserved for BKG<br> 524 600-699 reserved for GEOSCIENCE AUS<br> 525 700-799 others<br> 526 etc 527 </p> 528 <p> 529 The number of bytes in each real time message includes the header as well as the data content, but NOT the pointer. 530 </p> 531 <p> 532 For example: 533 </p> 534 <ul> 535 <li>A station message is output once per hour and is 20 bytes.</li> 536 <li>An observation message is output once per second. The header is 12 bytes long and the SOC data is 21 bytes per PRN. So a typical RTIGSO_T message will be 390 bytes if 8 sats are being tracked.</li> 537 <li>An ephemeris message is output when the ephemeris is decoded by the GPS receiver. The time in the Ephemeris header is the collected time. Only one ephemeris can be bundled in a RTIGSE_T message.<br> 538 A RTIGSE_T message contains one eph. The message consists of 12 header bytes and 72 ephemeris bytes, for a total of 84 bytes.</li> 539 <li>The RTIGSM_T (met) message should be issues once every 15 minutes. A basic met message consists of a 12 byte header and 3 longs (temp, press and relative humidity) for a total of 24 bytes.</li> 540 </ul> 541 <p> 542 All records are related to a station configuration indicated by the Issue of Data Station (IODS). The IODS will enable the user to identify the equipment and software that was used to derive the observation data. 543 </p> 544 <p> 545 Each record header contains the GPS Time in seconds which is continuous from 6 Jan-1980. 546 </p> 547 <p> 548 The data payload of each record consists of observations. The structures indicate a pointer to data but in fact the broadcast messages do not contain the pointer, only the data. Users will have to manage the data and the pointer is shown to illustrate where the data is located in the message and one possible data management option. 549 </p> 550 <p> 551 All record data are in network byte order (Big Endian), i.e. IA32 users have to swap bytes. 552 </p> 553 <p> 554 Visit <u>http://igscb.jpl.nasa.gov/mail/igs-rtwg/2004/msg00001.html</u> for further details. 507 555 </p> 508 556
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