Gentle Reminder Gps Failures

[Meantime]

Just a reminder that some older style GPS systems that cannot, or do not accept a firmware upgrade may fail on the 6th April due to a bug that means they can not handle the forthcoming epoch rollover properly. So if your GPS stops working you will know why!

[TheQ]

And for once that one is NOT an April fool..

[LizG]

I mentioned this topic to my husband this afternoon.  He now knows why the date on our GPS keeps reverting to 1999 - a few months back he spent a long time wondering why!!!!

[Meantime]

I'm not sure why it's failing now, but some are due to fail on the 6th April. This is because GPS signals from the satellites include a timestamp that is needed to calculate your position and part of this, the week number, is stored using ten binary bits. This means that the week number can have 2 to the power of 10 or 1024 values, counting from zero to 1023. Every 1024 weeks or roughly every 20 years the counter rolls over from 1023 to zero.

The first Saturday in April will mark the end of the 1024th week, after which the counter will spill over from 1023 to zero. The last time the week number overflowed like this was in 1999, nearly two decades on from the first epoch in January 1980.

Newer GPS devices will have been designed with this roll over in mind, older ones may not have taken it into account and may behave unpredictably. Its a bit like the famous Y2K bug.

I have a very old Garmin eTrex, I'll let you know on Sunday if it is junk, or still works.

[LizG]

It was noticed back in November when we downloaded the waypoints from our recent holiday in India - suddenly all the dates had reverted to 1999!

[grendel]

I always thought the gps got its time and date from the satellites.

[Matt]

I have a very old Garmin eTrex, I'll let you know on Sunday if it is junk, or still works.

Thanks- saves me digging it out the loft to check!


Sent from my iPhone using Norfolk Broads Network

[Meantime]

59 minutes ago, grendel said:

I always thought the gps got its time and date from the satellites.

It gets a timestamp from the satellites that it uses to work out your location. The timestamp is effectively an incremental time from the last epoch. The week number part of that is stored using a limited number of digits which means the week number can never be greater than 1024, at which point it has to roll over. Very similar to the Y2K bug where no one thought to reserve 4 digits for the year, only 2 digits to represent the bit that went after 19. Off course in the year 2000, for a lot of old systems they rolled over to 1900. The GPS bug is more about it will probably fail to work out your location, or give you a wrong location,  if it cannot handle the roll over, as opposed to displaying the wrong date.

[Meantime]

23 minutes ago, Matt said:

 

 

Thanks- saves me digging it out the loft to check!


Sent from my iPhone using Norfolk Broads Network

 

Hey, if it still does the job, why replace it. That's my motto. Mind you at nearly 15 years old it doesn't owe me anything, so I have scraped together a few pennies for a replacement if needed.

[SteveO]

Our 15 year old Garmin still works perfectly. 

[Bluebell]

So does our 16 year old Garmin. 

Any advance on that?

[Smoggy]

My main chartplotter is fine, as my old etrex and 60csx, good old garmin.

I've heard of a few lowrance units having a hard time but I think the problem is the update that was meant to fix them.

[grendel]

i went on the tom tom site and there was an update to prevent failure, but it told me mine was fine.

[Meantime]

Yep mine is still chugging away fine!

[FrankHughes]

As I understand as stated earlier due to the binary system, and unexpected use many many years ago as to what all systems work today then infinity has been kind of defined and systems etc will need updated or changed, esp older chipsets,  based on older algorithms , then digital or whatever. My 12 year old son has been trying to 3xplain it to me. I am not sure if it’s tru3 or just trying to confuse me to fork out more money . In order to allow him to stay in a darkened smelly room, talking to virtual friends ,living in a virtual world. ... sorry  I am digressing and having a wee daddy rant. 

Try your phon3 and some up to date apps. There is a chap . I have seen many of his blogs, Captain somthing. He seems cool and appears to have apps on his phone. 

Keep on chugging. 

Kind regards 

Frank

 

 

[MauriceMynah]

I wonder if this is linked or just a coincidence. I had to go somewhere on the 12th of this month and needed to use my garmin (a baby at just 14 years old.) It got me where I wanted to go ok but shortly after couldn't find any satalites. It was out of touch with the satalites for about half an hour but suddenly found them again and seems to be working fine ever since. Was it doing the download?

[marshman]

Or was it some world/alien power blocking everything just to throw us all out of kilter???

How I love a conspiracy theory!!!!! Don't believin them though!!!

[MauriceMynah]

Of course MM, I should have realised, the Worlds satnav system has been reprogramed to show the Broads as a full fledged National park.

Who on earth could have committed such a dastardly deed ??!

[Vaughan]

I'm all right. All my Michelin road maps are still working perfectly.