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GPS Problem

howard

Howard Holzapfel
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Has anyone seen this warning about GPS Failure this Saturday
21st August? I have an Autohelm GPS and had quick look at their
web site and found no information. I am cruising the French
coast at the moment and can't find out anymore. The UK
government have made no effort to warn yachtsmen and say it's a
US Government system and we use it at our own risk! 'The rollover problem, also know as EOW (End of Week), is a
problem with the Global Positioning System network of satellites
and ground receivers.On Aug. 21, at 13 seconds before midnight GMT many GPS could
stop working or malfunction thanks to a design quirk. Consumer GPS systems are most at risk, say experts.Week Number Rollover refers to the way dates are processed in
GPS satellites. They track the date by counting weeks -- up to a
total of 1,024. At week 1,024, the counter rolls over to zero
and it will begin counting again. The GPS calendar started Jan.
6, 1980 and will reset for the first time on Aug. 21. If a receiver has difficulty determining the correct date at,
before, during and after this rollover, it may process data
incorrectly. "It is probably safe to say that all receivers with the latest
firmware versions currently on the market will not experience
problems during or after the rollover," explains Richard
Langley, a GPS expert at the University of new Brunswick in a
column in GPS World magazine."Older receivers may or may not have trouble, and the severity
of the problem could vary from manufacturer to manufacturer and
model to model. Some manufacturers are offering firmware
upgrades for selected older receivers to cure rollover problems."In an interview, Langley said most receivers manufactured after
1994 should be able to handle the rollover without incident.'
''''' "GPS receiver problems could range from minor to serious," said
John Lovell, Director of Quality, at Trimble Navigation Ltd., a
Sunnyvale, Calif.-based GPS company."Some receivers and associated application equipment, such as
electronic charting systems, could inaccurately process GPS
satellite signals and produce incorrect positions, possibly
unknown to the user."Some receivers may not be able to locate the satellites and not
work at all and receivers may appear to be working while
displaying an inaccurate date.On the water, there's a slightly higher risk for both commercial
and pleasure craft operators. Everyone with GPS equipment is
being advised to check their systems.

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Depending on when you bought the Autohelm GPS, and the date that Raytheon took over Autohelm your GPS may be ok. But then again, by now you may have found out that it is counting the correct week. Raytheon has said that all of their later models handle the rollover without problems.I do not know the Raytheon web site, but it is probably Raytheon.com. I purchased mine in 1996 and it has handled the rollover just fine. JHH
 
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