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GPS oddity

Started by charliecoutas, Oct 21, 2024, 04:36 PM

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charliecoutas

Seventeen years ago I put my home-made heating/solar (hot water) controller into operation (PIC of course). It has undergone several changes and updates over the years and a GPS module, which was there from the start, provided the time of day, month etc. A later addition provided that same time in our bedroom via an HC-12 radio link.

Yesterday the time was one hour early and a date of Sunday 7 March 2005!  I spent ages ploughing through my code trying to discover my error. The time was correct for the time of year (British Summer Time). Eventually I got down to the GPS message that gives the date and it showed 070305.

Googling around revealed that there was a "rollover" error and that old versions of GPS receivers "might need updating". I couldn't identify the unit I had but a different one in my junk box now works as expected. The bad until went into the bin.

So if you get GPS problems, this might just be the reason.

Charlie


david

Sounds like the 10 bit week register roll over.

https://www.gpsalliance.org/post/gps-week-number-rollover-explained

Cheers,
David