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Will your GPSr know what time it is?

Discuss GPS Hardware, Technical Issues, etc. here.
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Will your GPSr know what time it is?

Post by littleblkdog »

I thought I had already seen a thread on here about this issue. Since I can't find it, here is some info:

Bottomline: You should check with your GPSr manufacturer to make sure you have the most up-to-date software version before April 6th. If you don't, your GPSr might not know what time it is or might not work at all particularly for older models after April 6th, 2019. GPS chips/software in phones should NOT be affected (cue superiority claims from phone geocachers). Updating the software in your GPSr is usually pretty easy and most manufacturers have a program to help or you download a file, connect your GPSr and then run the file which will automatically update your GPSr.

More technical details interesting but not super important: On April 6th, 2019 GPS will enter its third epoch. GPS uses a system of numbering the weeks to tell what time it is referenced from the starting week. With a 10 bit date field, there is a 1024 week limit which means every 19.7 years you need to start over. Older GPSr may not process this week rollover correctly causing time issues and other unpredictable behavior. This may or not affect navigation but will almost certainly affect the unit time in an unpredictable way. So you might still be able to find geocaches if your unit works but the time stamp on the found it log would be incorrect.

This article has some good details: SAVE THE DATE: GPS WEEK NUMBER ROLLOVER EVENT – APRIL 6TH 2019
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Re: Will your GPSr know what time it is?

Post by joejackson »

Thanks for posting that! I read about this a couple of weeks ago. My first thought was "How can this happen right in the middle of CAM?!?!?!" Then I realized the Air Force and those guys out in Colorado probably aren't concerned about CAM. Nor were they 2,040 or so weeks ago when 10 bits seemed like a lot.

Anyway, I installed the most recent GPSMap 64 update and after a second reboot everything seems OK. See you on the CAM trail. Or maybe in some South American version of Allegany County when the epoch rolls over...
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