Maretron gps100 Manuale Utente

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Revision 1.2 
 
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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).