Maretron GPS100 - Manual (Page 19)

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Revision 1.2 Appendix A – NMEA 2000 ® Interfacing Page A3
PGN 129029 – GNSS Position Data
The GPS100 uses this PGN to convey a comprehensive set of Global Navigation Satellite
System (GNSS) parameters, including position information. The factory default for periodic
transmission rate is once per second. The transmission of this PGN can be disabled (see PGN
126208 – NMEA Request Group Function – Transmission Periodic Rate).
Field 1: SID – The sequence identifier field is used to tie related PGNs together. For
example, the GPS100 will transmit identical SIDs for 126992 (System Time), 128259
(Speed), 129026 (COG and SOG, Rapid Update), 129029 (GNSS Position Data),
129539 (GNSS DOPs), and 129540 (GNSS Satellites in View) to indicate that the
readings are linked together (i.e., the data from each PGN was taken at the same
time although they are reported at slightly different times).
2: Position date –UTC Date in resolution of 1 day (The number of days since January
1, 1970).
3: Position time – UTC Time in resolution of 1x10 -4 s (24 hour clock, 0.0000 =
midnight).
4: Latitude – Latitude in 1x10 -16 degrees ("-" = south, “+” = north)
5: Longitude – Longitude in 1x10 -16 degrees ("-" = west, “+” = east)
6: Altitude – Altitude referenced to WGS-84 in (resolution of 1x10 -6 m)
7: Type of System – This field is used to indicate type of GPS system. The GPS100 will
show either 0 (GPS) or 3 (GPS+SBAS, factory default) dependent on whether the
user has enabled SBAS.
8: Method, GNSS – This field is used to indicate the quality of GNSS information. The
GPS100 indicates one of the following values: 0=no GPS, 1=GNSS fix, 2=DGNSS
fix, 6=Estimated (dead reckoning).
9: Integrity – This field always contains a value of 0 (no integrity checking).
10: Reserved (6 bits) – This field is reserved by NMEA; therefore, this field always
contains a value of 0x3F (the GPS100 sets all reserved bits to a logic 1)
11: Number of SVs – This field is used to indicate the number of satellites used in
solution.
12: HDOP – This field is used to indicate the horizontal dilution of precision with a
resolution of 1x10 -2 (unitless).
13: PDOP – This field is used to indicate the positional dilution of precision with a
resolution of 1x10 -2 (unitless).
14: Geoidal Separation – This field is used to indicate the Geoidal Separation in
resolution of 1x10 -2 m.
15: Number of Reference Stations – This field always contains a value of 0
16: Reference Station Type "1" – This field always contains a value of 0xF (Null)
17: Reference Station ID "1" – This field always contains a value of 0xFFF (data not
available)
18: Age of DGNSS Corrections "1" – This field always contains a value of 0xFFFF (data
not available)
PGN 129539 – GNSS DOPs
The GPS100 uses this PGN to provide a single transmission containing GNSS status and
dilution of precision components (DOP) that indicate the contribution of satellite geometry to
the overall positioning error. There are three DOP parameters reported, horizontal (HDOP),
Vertical (VDOP) and time (TDOP). The factory default for periodic transmission rate is once