Thread: Heads up - GPS Week Rollover on April 6th

Just a heads up for those using older GPS units. What is happening is that the whole basis of how GNSS systems (including the US Navy system "GPS") work is the quality of timing. If the time information in the radio transmission fails or changes relative to the others, GPS doesn't work! They all need to be in sync. The Statilites only carry a 10-bit string for time and at the end of March this year, this week information is going to be reset from 1023 to 0 weeks. Since the original deployment of GPS in 1980, the week number has rolled over once in 1999 and will roll over again this year.

What does this mean to you? on the 6th of April, 00:00 UTC, the Week rollover will be reset. This means that your handheld GPS (especially older ones) may screw you over if you are using it for navigation.

How to prepare (if you care) in case it all goes tits up. You have some options:

1. Upgrade to newer unit
2. Don't rely of it for navigation around this time (mid roar for most of you)
3. Get the firmware of the unit upgraded to the latest - normal from the manufactures website
4. Have a map and compass and know how to use them

Happy to answer any questions I can, but some of this shit is pretty high on the geek level and above my head too.


https://www.usno.navy.mil/USNO/time/...umber-rollover

You prompted me to check the firmware updates on my 62s, there were two updates available so updated it. It'll be interesting to see if this rollover causes any trouble.

Like wise. Garmin had a GPS firmware update for my rino 750 which is quite new. Hopefully issue sorted.

Thanks for heads up

I know we have more pressing issues at the moment but I checked my old Garmin yesterday and it seems fine, Date correct, time correct, locked onto satellites fine.

My garmin Oregon 500 seems fine. It's about 10 years old and I dont recall doing firmware for a long time. I suppose garmin must have anticipated the rollover or else an updated firmware got it a while back.

I updated my software a while ago. Will see what it is like this weekend