NorthStar Navigation GM1708 961XD User Manual
Page 51
SECTION TWO - Installation
961 INSTALLATION MANUAL Revision A
Page 41
DGPS ANTENNA
(cont’d)
High beacon SNR or low signal.
When vessel interference is still present:
When the source of the interference is
found:
•
Turn off all electrical devices and
equipment on the vessel, then check
for improvement. Check fluorescent
lights, gauges, and so forth. Be cre-
ative! Check for power-line interfer-
ence by moving away from the dock
and/or the marina. Verify that the
antenna is mounted in accordance
with the recommendations shown in
Figure 5.
•
Isolate to the interfering device, with
breaker panel if necessary.
•
Experiment with different grounding
locations (the best ground is the
ocean). Drop a temporary wire
attached to 8410 black wire over the
side of the vessel to see if the interfer-
ence source can be fixed by ground-
ing techniques.
•
Disconnect shore power and move
away from the dock and/or marina
(power lines and lights can cause
interference).
•
Temporarily relocate the 8410 or
combo antenna as far away from the
interfering source as possible, and
monitor the effect on reception. If it
improves, consider relocating the
antenna or try to determine if the inter-
ference can be eliminated at its
source.
•
Normally, noise that affects an 8410
DGPS coupler won’t affect a combo
antenna and vice versa. Consider
temporarily changing antenna types
to determine the effects on signal
reception.
DGPS ANTENNA
(cont’d)
Poor, intermittent, or no beacon signal using
a known-good loop or combo antenna.
•
Check the proximity of the antenna to
radar antennas or other transmitting
devices, such as INMARSAT. A
radome can affect H-field antennas
even when power is off. Hint: To test
for the best location, move the
antenna and coax to temporary loca-
tions using an over-the-deck length of
coax, then relocate as necessary.
a. The GPS receiver AA180 supplies the 5.5 VDC to the AN150 active GPS antenna.
Table 3: Troubleshooting the GPS/DGPS antenna installation (continued)
Antenna
Symptom
Possible Solutions/Reasons