Installation guide

22 |
NSS | Addendum for RTM-2, RTM-2.5 and RTM-3
EN
Position update rate
Adjusted to suit the type of vessel the GPS receiver is fitted to, and to minimise unnecessary
NMEA 2000 data traffic. For high speed vessels and performance sail boats, the maximum
update rate will be desired for measuring performance to the highest possible accuracy. On
slower vessels and large networks with a lot of network traffic, high update rates may be of
little value. High update rate may be preferable to reduce the network load, as well as reduce
the visual distraction of constantly changing values.
COG/SOG Filter
This filtering smoothens the output data with averaging. The best setting will depend of type
of vessel and user preference.
Instance
If more than one device of the same type exists in the network, the instance number may be
changed to a unique number to allow easier identification.
GNSS
1. Return to the GS25 Antenna device information dialog
2. Select the GNSS panel button to access the GNSS setting
The GPS and GLONASS options may be enabled simultaneously, or one at a time. Generally
GPS offers the highest accuracy, but in certain circumstances a better fix may be achieved
with both or GLONASS only enabled. A basic indication of performance can be seen on the
Satellites page. Once a fix is acquired, EPE and HDOP should be noted and compared - lowest
values for each indicate the best position fix.
Compass calibration
Prior to configuring, the GS25 compass must be calibrated. This is done as described in the
GPS Antenna installation guide, or as described below.
Before the calibration is started, ensure that the compass is mounted securely in its’
permanent location.
The calibration should be done in calm sea conditions and with minimal wind to obtain good
results. Follow the on-screen instruction, and use about 60-90 seconds to make a full circle.
1. Start the calibration by selecting the Calibrate button in the device information dialog
2. Follow the online instructions
During the calibration, the compass will measure the magnitude and direction of the local
magnetic field.
• If the local magnetic field is stronger than the earth’s magnetic field (the local field is reading
more than 100%), the compass calibration will fail
• If the local field is reading more than 30%, you should look for any interfering magnetic
objects and remove them, or you should move the compass to a different location. The
(local) field angle will guide you to the local interfering magnetic object.
Compass conguration
1. Tap the GS25 Compass line in the device list to display the GS25 Compass device
information dialog.
Compass oset
The difference between the compass lubber line and the boat’s center line should be
compensated for.
2. Find the bearing from the boat position to a visible object. Use a chart or a chart plotter
3. Steer the boat so that the center line of the boat is aligned with the bearing line pointing
towards the object
4. Change the offset parameter so that the bearing to the object and the compass readout
becomes equal
¼ Note: Make sure that both the compass heading and the bearing to the object have the same
unit (Magnetic or True).