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Old 18-04-2019, 07:59   #1
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Join Date: Aug 2009
Location: charleston
Boat: bristol 27
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gps rollover

I think I have two afflicted devices.

The rollover issue itself is caused by the fact that GPS systems count weeks using a ten-bit parameter. This means they start counting at week zero and reset when they hit week 1,024. The first count (or “GPS epoch”) started on January 6th, 1980, and the first reset took place on August 21st, 1999. That means the next one is due April 6th this year.
They both report the year as 1999 now.

Neither can get a fix very easily under the deck anymore when they both used to, but in clear view, they still both work and seem just as accurate as before. Why?
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Old 18-04-2019, 09:22   #2
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Boat: Rangeboat 39
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Re: gps rollover

If they are, you may find your receivers start to behave strangely on – or more likely at some point after – 6 April 2019. The data they output may suddenly jump backwards in time, putting timestamps on your timing and navigation data that are nearly 20 years out of date.

This won’t affect the receiver’s ability to navigate and/or calculate precise time from the day level down to the microsecond level. But it will create week, month and year timestamps that are wildly wrong, which could seriously impact any systems and applications that rely on GPS data at that level.

Critical after effects and what you should do

On Saturday 6 April 2019 the behavior of an erroneous GPS receiver may vary: from providing incorrect date/time information (e.g. incorrect UTC Time due to failure on the GPS Time-to-UTC conversion algorithm) to leading up to the complete failure of the receiver. Also be aware that some manufactures implement the week number referenced to a date different than 6 January 1980 (e.g. the firmware date is used as reference). These devices would not be affected by the GPS Week Rollover on the 6 April 2019, but rather the problem would occur on a different date.
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