Maretron GPS100 - Manual (Page 9)

® ®
Revision 1.2 Page 5
2.4.1 Checking Connections
Once the NMEA 2000 ® connection to the Maretron GPS100 has been completed, check to see
that heading information is being properly transmitted by observing an appropriate display.
Refer to Section 5, “Troubleshooting”, if no heading information appears.
3 Operation
As shipped from the factory, the GPS100 automatically provides position, time, SOG, COG,
magnetic variation, and satellite information and requires no user configuration. However,
some of the GPS100 parameters are user configurable as described below:
• Desired Operating Mode – the GPS100 may be programmed to operate in 2D mode, 3D
mode, or the best available operating mode (factory default)
• SBAS (WAAS) – the GPS100 may be programmed to use SBAS (WAAS) using the best
available SBAS satellite (factory default). A specific SBAS satellite may be specified, or
SBAS may be disabled altogether.
• SV Elevation Mask – as shipped from the factory, the GPS100 uses all visible satellites
in its position solution, regardless of the elevation (angle above the horizon). A user
may specify a SV Elevation Mask, such that only satellites with an elevation greater
than this value will be used in the position solution.
• PDOP Mask – as shipped from the factory, the GPS100 will report a GPS fix whenever
possible, regardless of the value of position dilution of precision (PDOP). A user may
specify a PDOP Mask, such that whenever the PDOP is above the specified value, the
GPS100 will report that no GPS fix is available.
• SNR Mask – As shipped from the factory, the GPS100 will use all detectable satellites
in its position solution, regardless of the signal-to-noise ratio (SNR). A user may specify
a SNR mask, such that such that only satellites with an SNR greater than this value will
be used in the position solution.
• Antenna Altitude – A user may specify an antenna altitude for use when the GPS100 is
operating in 2D mode. As shipped from the factory, the GPS100 will use the altitude
calculated when it was last operating in 3D mode.
• Periodic Rate of Transmission – As shipped from the factory, the GPS100 transmits
PGNs at a periodic rate. Alternatively, a PGN can be disabled by programming its
periodic rate to zero.
These parameters may be configured using a Maretron instrumentation display, such as the
Maretron DSM200, or other NMEA 2000
® chartplotters or instrumentation displays with GPS
configuration capability. Please refer to your chartplotter/display manual for details.
Users with direct access to the NMEA 2000
® interface may configure these parameters directly
through the NMEA 2000 ® interface. Please refer to Appendix A for a description of the NMEA
2000
®
messages used to configure these parameters.
3.1 Magnetic Variation
Magnetic variation is the angular difference between the true meridian (great circle connecting
the geographic poles) and the magnetic meridian (direction of the lines of magnetic flux).