Table of Contents
Advertisement
3 Operation
As shipped from the factory, the GPS200 automatically provides position, time, SOG, COG,
magnetic variation, and satellite information and requires no user configuration. However, some
of the GPS200 parameters are user configurable as described below:
Device Instance - If you have more than one GPS on the vessel, you can configure unique
instances so listening devices can distinguish one GPS from another.
Installation Description - You can configure a couple of special text fields within the
GPS200 with any text you desire. If you do configure these text fields, they will show up
with certain diagnostic tools (e.g., Maretron's N2KAnalyzer software) and are useful for
things like location or when and who installed the GPS200.
Periodic Rate of Transmission – As shipped from the factory, the GPS200 transmits
PGNs at a periodic rate. Alternatively, a PGN can be disabled by programming its periodic
rate to zero.
Label - Labels are useful for identifying particular products on the network. For example
you might have two GPSs, one labeled "Primary GPS" and the other labeled "Backup
GPS". When you go to build your favorite screens on Maretron's DSM250 dedicated
display or N2KView software, you can easily identify which GPS you want to use for that
favorite screen.
Satellite Based Augmentation System (SBAS) – the GPS200 may be programmed to use
differential correction or SBAS (WAAS in USA, EGNOS in Europe, MSAS in the Far East),
which is the factory default. You may disable the SBAS capability if desired.
These parameters may be configured using a Maretron display (DSM250), or the parameters
can be configured using a Maretron NMEA 2000
N2KAnalyzer software.
Users with direct access to the NMEA 2000
through the NMEA 2000
®
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).
Magnetic variation has different values at different locations on the earth with most areas
undergoing change to the magnetic variation over time.
The GPS200 indicates magnetic variation anywhere on Earth using the World Magnetic Model
(WWM). It is important to understand that the WMM geomagnetic model only characterizes that
portion of the Earth's magnetic field that is generated in the Earth's fluid outer core (the main
magnetic field). The portions of the geomagnetic field generated by the Earth's crust and upper
mantle, and by the ionosphere and magnetosphere, are not represented in the WMM.
Consequently, a magnetic sensor such as a compass or magnetometer may observe spatial
and temporal magnetic anomalies when referenced to the WMM. In particular, certain local,
regional, and temporal magnetic declination anomalies can exceed 10 degrees. Anomalies of
Revision 1.3
®
®
interface. Please refer to Appendix A for a description of the NMEA
/USB gateway (USB100) and Maretron's
®
interface may configure these parameters directly
Page 5
Advertisement
Table of Contents
