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Northstar M121/M84 Installation and Operation Manual104
B-2 GPS navigation problems
2-1 No GPS fix or long time to get fix at
startup:
a May occur occasionally if the antenna does
not have a clear view of the sky. The satellite
positions are constantly changing.
b Antenna cable not connected to display
unit.
2-2 Instrument GPS position different from
true position by more than 10 m (33 ft):
a Instrument in simulate mode. Turn simulate
mode off (see section 19-16).
b The normal error in GPS position will exceed
10 m (33 ft) for about 5% of the time.
c Under special circumstances the US
Department of Defence may introduce a
deliberate and changing error in the GPS
positions of up to 300 m (1000 ft).
2-3 Instrument position different from
same position on local charts:
a Instrument in simulate mode. Turn simulate
mode off (see section 19-16).
b Incorrect chart datum. Select the correct
chart datum (see section 19-2).
c Map shift has been applied wrongly. Clear
map shift, then reapply if necessary (see
section 19-2).
2-4 Can not see boat on chart:
Press
ESC
to switch to centre on boat
mode (see section 3-2-1).
2-5 The time or date on satellite display is
wrong or off:
a No GPS fix.
b In simulate mode. Turn simulate mode off
(see section 19-16).
c Local time offset is wrong (see section 17-12).
The Local Time Offset must be changed
when daylight saving time starts or ends.
2-6 Autopilot not responding to
Instrument; no NMEA output:
a NMEA output disabled or the required
NMEA sentences are not turned on. Check
NMEA settings (see section 19-12).
b Check that the instrument is connected
correctly.
2-7 No DGPS fix or loss of DGPS fix:
a To receive a DGPS fix, WAAS/EGNOS must be
enabled or an optional DGPS antenna fitted
(see section 8).
b With WAAS/EGNOS: Boat out of coverage
area (see section 8).
c With WAAS: GPS antenna does not have
a clear view of the horizon towards the
equator.
b With beacon DGPS: boat out of range of a
DGPS beacon.
3-1 Fuel used or remaining seem
inaccurate:
a Instrument is not wired for auto power (see
section 20-4).
b In rough seas, fuel may surge back and forth
through the fuel transducer, resulting in
incorrect readings. Try installing a one-way
valve between the fuel transducer and the
fuel tank.
B-3 Fuel consumption problems
c The Set remaining fuel value must
be reset after every refuelling (see section
113 -1) .
d The fuel tank may not refill to the same
capacity each time due to air pockets.
This is particularly noticable with underfloor
tanks.
e Fuel transducers wear out over time and
should be replaced after every 5000 litres of
fuel.