Is our GPS losing it?

[samwise]

WE have an MLR FX 312 which has, so far behaved impeccably. However, this last week-end it suffered a couple of worrying lapses. In both cases when on the Nav setting it suddenly started to count down the SOG reading to zero and took out the course heading, which is the other component of that display.

In both cases it was restored with a re-boot i.e. switch off and start again. Any ideas why it should do this? Do we have a problem Houston or is the problem with the satellites?




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[MainlySteam]

There have been a number of posts on GPS user end reliability recently. While errors may indeed be due to a problem in the receiver, or with visibility of the satellites I am not sure how many are aware that other on board radio frequency generating equipment (does not have to be a transmitter, can be any of a wide variety of electronic equipment) can interfere with GPS receivers.

As one example, the US Coast Guard has a safety alert for various models of active TV/Radio receiving antennas which are known to have interfered with GPS receivers - that was a route we recently had to go down as a double check as we had specified an antenna from one of the affected manufacturers for two new build vessels (the specified antennas were "clean" however).

These things are not automatically a problem, our own GPS receiver/antenna is only 300-400 mm away from an active TV receiving antenna and there has never been an issue with it. Just something to keep in mind if you are getting unexplained GPS problems.

John

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[Alex_Blackwood]

It may not help you, but could be of interest and worth bearing in mind.
I remember a similar problem with a GPS unit. Allbeit on a merchant vessel, but similar sort of unit. After reading the hand book we found that it stated That small errors could become accumulative, causing all sorts of problems, shutting down and restarting with factory defaults was the answer. This was done and problem solved.
Without going into all the technical gobblydegook the errors were, basicaly, caused when the unit had been switched on with the vessel at anchor for a couple of weeks.


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