For those of you who haven't noticed, your GPS may have become a time traveler this week.
The GPS system was invented in the 1980s and uses an epoch of Jan 1, 1980 as the starting point for calculating dates. Many computers represent dates as a 32-bit count of seconds, which rolls over in 2038, but work is happening to extend the range before that happens.
The GPS system uses a 10-bit field for the week number. 10 bits can express a number from 0 to 1023, which is 19.6 years.
Jan 1 1980 plus 19.6 years = August 1999. We have had one rollover event.
Various companies dealt with this in various ways, much like we handled the year 2000 debacle.
The usual way to deal with this is to write a kludge into the firmware saying, "add 1024 to the week number received from the satellite".
You can see the problem with this particular trick: It only works after the rollover.
If you are shipping a unit that is going to span the roll over period, you write a hack like this: "if week number less than 950, add 1024 to it" The number 950 would allow you to ship units about 1.5 years before the rollover, and not get caught.
This is what DeLorme did, I think with an 8 month lead.
I don't know what DeLorme models were affected. My PN-60w is one of the affected ones. It started time traveling last summer.
Addendum: After two hours under an open sky it has not been able to get a fix
Addendum 2: It was going to sleep before getting a fix. Told it to not go to sleep while immobile, and it locked in a few minutes.
I don't know how this affects SPOT devices.
In the intervening years, DeLorme was bought by Garmin.
On another forum, I found someone who contacted Garmin, and basically was told, "Sucks to be you, we're not giving support on a discontinued brand" They phased it more politely than that.
To be sure: This does NOT affect the accuracy of the GPS location. But recorded tracks will be transfered to your computer 19.6 years older than reality.