NorthStar MX500, Operator'S & Installation Manual

Page: 185 / 284

Version 3.0
171
Engineering Mode Operator’s Manual
A common source of memory corruption is an aged Lithium memory
back-up battery. This will result in either a slow deterioration of memory
retention or it may abruptly dump all its memory.
BNT-ME recommends the battery be changed every 2 to 3 years of
operation by an authorized technical dealer. Marine electronics deal-
ers or radio shops will typically stock the replacement battery, Lithium
type TL-5902, 3.6V (1/2 AA).
GPS - GPS CDU Troubleshooting
GPS3 - Visible Satellite Information
This screen provides some basic information about the MX smart GPS
antenna performance, in that it is basically an extension of
GPS1 screen.
It tells you what satellites are available to track at the moment under
the PRN number. The signal strength of satellites under track is in the
second column labeled S/N. The weakest signal strength that the GPS
receiver can track is 25. However, any satellite with a signal strength
under 32 is considered
troubled , and the GPS receiver will not use that
satellite in the navigation solution. Troubled satellites tend to cause
position jumps and greatly reduce the accuracy of the GPS position fix.
The
EL , AZ , and STA values represent the satellite’s Elevation and
Azimuth , and Almanac Status respectively.
Low signal to noise (S/N) quality numbers may be an indication of
local interference from on-board electronic equipment such as Radar,
INMARSAT, VHF, SSB and other high power transmitters. Review
the installation of the entire system to ensure you have followed proper
procedures for cabling, power, and, most importantly, grounding and
antenna placement. The majority of these problems will be resolved by
better grounding and antenna location selection. Regarding ground-
ing, the water intake for the engine, or any other electrical ground
relying on the engine or generator for Earth ground, is not good for the
GPS and
especially the beacon receiver.