Author Topic: GPS WNRO. No, really!  (Read 64 times)

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Offline Phmode

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GPS WNRO. No, really!
« on: April 05, 2019, 10:44:55 am »
The satellites that provide the GPS signals for our sat nags is coming to one of its crunch points.

The clocks on board the sats have a limited number of fields for holding the week number data.

At midnight tonight, the fields will get full as the clock rolls over to 99999 whatever.

This means that at midnight tomorrow, Saturday, the clocks will roll-over, like an old-fashioned mechanical mileometer to 000001 whatever.

Now, here's the fun bit (pun intended) because older gadgets that use the GPS signal 'may' not be able to cope with Week Number Roll-Over. This roll-over happens every 21 years from memory (might jave been 19) but the last one was in the eighties. My tlescopes e.g. may well never find the heavens in the right place again as they were both made after the last roll-over so I don't know if they 'proofed' against it. Meade, who make the scopes, are burying their heads in the stars.

Some chip manufacturers ensured their devices could cope with the WNRO but others, and older ones, may not have done.

So, all sorts of things may or may not work come Sunday morning, the US air force may bomb Nevada, UK subs may fire Tridents willy-nilly at anything that doesn't move, older 747's may land on the M4. So, Y2K all over again  ::)

Unsurprisingly, Garmin are totally ignoring this event and have cast their older devices to the devil!

More surprisingly and even more unexpectedly, TomTom have issued a one-time update for most of their old and no longer supported gizmos, so if you get an e-mail about it, don't ignore it as a late April 1st jape.

You can check your devices at the TomTom website and much kudos to them for doing the right thing.

Brian (who 'may' never be able to find his way home again  ::) )

Offline Belco100

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Re: GPS WNRO. No, really!
« Reply #1 on: April 08, 2019, 09:33:01 am »
Also, amazingly, a lot of companies still have old IT kit that gets its time source from the GPS system, so there was a lot of checking this out going on over the last few weeks.  :o

Not seen anything bad happen over the weekend, so probably limited to old GPS kit as you say.