Maretron GPS200 - Manual (Page 21)

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Revision 1.2 Appendix A – NMEA 2000
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Interfacing Page A5
GPS200 NMEA 2000
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Non-Periodic Data Transmitted PGNs
PGN 129538 – GNSS Control Status
The GPS200 uses this PGN to provide the GNSS common satellite receiver parameter status.
GPS200 sends this PGN only when requested by PGN 059904 (ISO Request).
Field 1: SV Elevation Mask – If the elevation of a satellite (angle above the horizon) is below
this value, the GPS200 will not use that satellite in the solution. Units are 1x10
-4
radians. The GPS200 always indicates “data not available” for this field, indicating
that this parameter is not user configurable.
2: PDOP Mask – If the PDOP exceeds this value, the GPS200 will indicate “No GNSS
fix” or “Dead Reckoning Mode” in PGN 129029. Units are 1x10
-2
(unitless). The
GPS200 always indicates “data not available” for this field, indicating that this
parameter is not user configurable.
3: PDOP Switch – If the PDOP exceeds this value, a GPS receiver will switch from 3D
to 2D mode. For the GPS200, this field always contains a value of 0x7FFF,
indicating that the GPS200 will always attempt to operate in 3D mode. Units are
1x10
-2
(unitless). The GPS200 always indicates “data not available” for this field,
indicating that this parameter is not user configurable.
4: SNR Mask – If the SNR of a satellite is below this value, the GPS200 will not use
that satellite in the solution. Units are 1x10
-2
dB. The factory default is to use all
available satellites. The GPS200 always indicates “data not available” for this field,
indicating that this parameter is not user configurable.
5: GNSS Mode – This field is used to indicate the desired mode of operation: 0 = 1D, 1
= 2D, 2 = 3D, 3 = Auto (factory default), 4-5 = Reserved, 6 = Error, 7 = Null. The
GPS200 always returns a value of 3 (Auto) for this parameter, which is not user
configurable).
6: DGNSS Mode – This field is used to indicate the desired mode of operation of
DGNSS (0=do not use SBAS, 1 and 3=Use SBAS when available). The factory
default value for this field is 1 (use SBAS when available).
7: Position / Velocity Filter – This field always contains a value of 0x3, indicating that
the GPS200 does not allow configuration of the position / velocity filter.
8: Max Correction Age – This field always contains a value of 0xFFFF, indicating that
the GPS200 does not allow configuration of the maximum age of SBAS correction
data to be used.
9: Antenna Altitude for 2D Mode – This field is used to indicate the antenna altitude for
the GPS200 to use when operating in 2D mode in units of 1x10
-2
m. The factory
default for this field is 0.0 m, and is not user configurable.
10: Use Antenna Altitude for 2D Mode – This field is used to indicate whether the
GPS200 will use Antenna Altitude (Field 9) when operating in 2D mode. The
GPS200 returns a value of 1 for this parameter, indicating that it will always indicate
an Antenna Altitude of 0.0m when operating in 2D mode. This field is not user
programmable.
GPS200 NMEA 2000
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Received PGNs
PGN 126208 – NMEA Command Group Function – GNSS Control Status