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Another GPS Y2K Problem Is Imminent

Article by: Darren Griffin
Date: 8 Mar 2019

Make a note of April 6th in your diary, on that date it's feared that many older GPS systems may stop working as yet another hard-coded date bug is triggered. The first such issue affecting GPS occurred on Aug 21, 1999.

Like the Y2K bug that caused a great deal of worry (but thankfully few issues), this one is caused by the exact same issue, a hard-coded 10-digit timestamp that will rollover on April 6th. When that happens, some older systems may be unable to calculate a positional fix.

The problem, like all these data bug problems, originates in the way that devices calculate time. Starting with the date of January 6, 1980, GPS devices count weeks using a 10-bit number field hard-coded into the software. With two to the tenth power being 1,024, that means that GPS devices with a 10-bit number field can count up to 19.7 years which was Aug 21, 1999 when calculated from January 1980. On that date, most GPS devices started counting from zero again without issue but some didn't. Now another 19.7 years has passed and the issue rears its head one again.

It should only affect old devices, certainly those manufactured since 2010 have used a system that won't roll over for more than 157 years, but if you have and still use an older GPS and it stops working this is why.

The U.S. Naval Observatory released a FAQ to forewarn of this issue in 2017 which is available here.

Source: gps.gov

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Posted by PeteB on Fri Mar 08, 2019 9:23 am Reply with quote

It's surprising how many people still say to me the whole Y2K thing was overhyped.

Sure, almost no real problems were widely reported, but that's because companies spent many millions checking systems where failure would be a serious problem and fixed the issues before the change of century. I worked in some such companies at the time and saw first hand just how much effort went into this.

In 1995 I actually discovered a real problem on a pocket electronic organiser, which, when syncing with a PC, changed all entries to the current century - I had noticed that a reminder to renew my passport in 2005 had suddenly become a reminder for 1905 - not much help. When I reported it to the manufacturer's (Casio) help line, at first I was met with disbelief - until I sent some detailed notes at which point their technical support guy sounded a bit more panicky. He later asked me to test an updated version of the sync software (via a floppy disk in the post!), and their workaround did the trick.

Hopton, UK

Posted by Kremmen on Fri Mar 08, 2019 9:54 am Reply with quote

I was also involved with fixing the Y2K problem before it hit.

The solution was easy once analysed.

Garmin DS61 LMT-D (In the car)
Garmin 2599 LMT-D (Indoor test rig)
Viofo A119 V3

Posted by datostar on Fri Mar 08, 2019 2:21 pm Reply with quote

My 2010 Renault Megane has the built-in TomTom Carminat SatNav, which fortunately uses an SD card for software and firmware updates along with the map data. TomTom recently advised individual registered users of this forthcoming problem and have provided new firmware for download to the card via the TomTom Home computer app. Bit of an involved procedure but I've now got it updated so should be OK come April. Might be more of a problem for vehicles with other systems not so accessible for updating.

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