GPS Week Rollover First Casualty

On the left: Garmin eTrex H (aka eTrex High Sensitivity), the 2007 update of the iconic yellow eTrex. (BTW - The screen is much more readable head on).

On the right: Garmin eTrex 10, released in 2011 (but purchased by me in 2018).

Why is the device on the left displaying a date in 1999? Because GPS just had a little Y2K style problem of its own. The 10 bit week number just rolled over to zero for the second time since the GPS system was switched on. Aside from the date being completely wrong, the device still finds a GPS position but it takes significantly longer to acquire satellites.

This has happened before in 1999 but back then GPS was much less of a consumer product (the first eTrex was still a year away) and most devices were programmed to cope with it. This time around though, there’s a lot of older, lower cost GPS devices still in use that may well have outlasted their manufacturers.

Fortunately the newer GPS signals have a 13 bit week number meaning this won’t be a problem again until 2137. For older devices still reading the 10 bit date/time, it’ll happen again on the 20th of November 2038 - 10 months after dealing with the other 2038 problem.

I bought the eTrex 10 to replace it because I don’t think there’s a firmware update coming for such an old device.

So I guess my eTrex H outlasted the 10 bit counter - now I guess we see if the eTrex 10 lasts until 2038…

Update: There’s a firmware update!