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4 Message Formats
52 MiLLennium GPSCard SW Version 4.503/4.52 Command Descriptions Manual Rev 2
station generating this Type 1 log. The log is of variable length, depending on the number of satellites visible and
pseudoranges corrected by the reference station. Satellite specific data begins at word 3 of the message.
Structure:
(Follows RTCM Standard for Type 1 message)
Type 1 messages contain the following information for each satellite in view at the reference station:
• Satellite ID
• Pseudorange correction
• Range-rate correction
• Issue of Data (IOD)
When operating as a reference station, the GPSCard must be in FIX POSITION mode before the data can be
correctly logged.
When operating as a remote station, the GPSCard COM port receiving the RTCM data must have its ACCEPT
command set to "ACCEPT port RTCM".
NOTE: Upon a change in ephemeris, GPSCard reference stations will transmit Type 1 messages based on the
old ephemeris for a period of time defined by the DGPSTIMEOUT command. After the timeout, the
reference station will begin to transmit the Type 1 messages based on new ephemeris.
RTCMA or RTCM1A
This log contains the same data available in the RTCM Standard Format Type 1 messages, but has been modified
to allow flexibility in using the RTCM data. The RTCM data has been reformatted to be available in ASCII
hexadecimal, utilizing a NovAtel header and terminates with a checksum.
This message was designed so that RTCM data can be intermixed with other NovAtel ASCII data over a common
communications port. The log is not in pure RTCM SC104 format. The header (
$RTCM) and terminator (*xx) must
be stripped off at the receiving end, then the data will need to be converted from hexadecimal to binary before the
RTCM information is retrieved. The RTCM data is further defined by the RTCM rule (see the RTCMRULE
command, Page 116).
The RTCMA log can be directly decoded by other NovAtel GPSCard receivers operating as remote stations. They
will recognize the $RTCM header as a special data input command and the differential corrections data will be
directly applied. The GPSCard remote station receiving this log must have the ACCEPT command set to
"ACCEPT port COMMANDS".
Structure:
Example:
$RTCM,664142406B61455F565F7140607E5D526A5366C7C7F6F5A5B766D587D7F535C4B697F54594
060685652625842707F77555B766558767F715B7746656B*54[CR][LF]
RTCMB or RTCM1B
This log contains the same data available in the RTCM Standard Format Type 1 messages, but has been modified
to allow flexibility in using the RTCM data. The RTCM data has been reformatted to be available in NovAtel
Binary Format, utilizing a NovAtel binary header.
$RTCM rtcm data *xx [CR][LF]
Field # Field Type Data Description Example
1 $RTCM NovAtel format ASCII header $RTCM
2 rtcm data hexadecimal representation of binary
format RTCM SC104 data
664142406B61455F565F7140607E5D526A5366C7
C7F6F5A5B766D587D7F535C4B697F54594060685
652625842707F77555B766558767F715B7746656B
3 *xx Checksum *54
4 [CR][LF] Sentence terminator [CR][LF]