GPS No Longer Accurate ?

[Alan de Enfield]

I have received a 'Notice To Mariners' from the Maritime & Coastguard Agency (MCA) as follows :


The MCA has issued a special safety bulletin to all mariners who use older GPS following a so-called 'week number rollover' event on 6th April 2019.


All GPS systems count time in weeks from 6th January 1980. The week number is stored as a 10-bit binary number which only allows for a maximum of 1,024 weeks before resetting itself to 0 (Zero). This rollover happened 6th April 2019 and all GPS receivers and systems using GPS Chips for both position and UTC which are 10 years old.


If it affected your GPS will show an incorrect date &/or time.



The US Department of Homeland Security has reported an error of one nano-second in the time equates to one foot of position error.


One Nano-second is one thousand -millionth of a second.
It wouldn't take much time difference/error to be a few miles off course.(one second would be 190,000 miles)

Edited May 25, 2019 by Alan de Enfield

[Momac]

My GPS devices are all a lot less than 10 years old. 

However this reminds me of the year 2000 thing which made loads of work for IT people . Apparently the IT people think they did a great job in avoiding a disaster. I say it was a job creation scheme.

What date is the next crisis?

[Alan de Enfield]

7 minutes ago, MartynG said:

What date is the next crisis?

Dunno, - but a walking form I am 'on' has had several members recently reporting their GPS showing weird dates and times so I posted it on there as well. Could be the answer they are looking for.

[dor]

I have an A10 Satmap - a gps device with OS maps which is mostly used by walkers.  I was one of the early adopters of this device, and I bought it in June 2008 so it is over ten years old.   It is showing the correct (UTC) time, and currently has a positional accuracy of 16 feet, which is about as good as you get without having a linked base station to compensate for the drift which is how the OS use the US gps (I understand the US military get positional accuracy down to a couple of centimetres).

 

I wonder if the people reporting errors on the walking forum are using an early Garmin, which was the only real alternative over ten years ago.  I've got a Garmin that is about twelve years old (only basic maps showing roads and rivers) but haven't used it for years (last time was in Australia about eight years ago).

 

I guess that as a result of Brexit we will have wasted many millions of pounds as we will get excluded from the European version of gps when (if?) we leave. We are apparently already developing our own version.

Edited May 25, 2019 by dor
Correct 'link' to 'drift'

[MtB]

1 hour ago, MartynG said:

Apparently the IT people think they did a great job in avoiding a disaster. I say it was a job creation scheme.

 

I think it was a lot more mundane than that, but the work had to be done. You'd be the first to complain if your council tax bill arrived with the wrong date on it, accompanied by a massive refund, I bet.

 

 

 

 

[IanD]

12 minutes ago, dor said:

I have an A10 Satmap - a gps device with OS maps which is mostly used by walkers.  I was one of the early adopters of this device, and I bought it in June 2008 so it is over ten years old.   It is showing the correct (UTC) time, and currently has a positional accuracy of 16 feet, which is about as good as you get without having a linked base station to compensate for the link which is how the OS use the US gps (I understand the US military get positional accuracy down to a couple of centimetres).

 

I wonder if the people reporting errors on the walking forum are using an early Garmin, which was the only real alternative over ten years ago.  I've got a Garmin that is about twelve years old (only basic maps showing roads and rivers) but haven't used it for years (last time was in Australia about eight years ago).

 

I guess that as a result of Brexit we will have wasted many millions of pounds as we will get excluded from the European version of gps when (if?) we leave. We are apparently already developing our own version.

We're only developing our own version in the minds of Brexiteers with no idea of how much it costs to put a constellation of navigation satellites into space and maintain them -- it's a big sum for the USA (GPS) or the whole of Europe (Galileo), it's a ludicrous one for the UK to pay on its own. A clue; it's not millions...

Edited May 25, 2019 by IanD

[nicknorman]

3 hours ago, Alan de Enfield said:

I have received a 'Notice To Mariners' from the Maritime & Coastguard Agency (MCA) as follows :


The MCA has issued a special safety bulletin to all mariners who use older GPS following a so-called 'week number rollover' event on 6th April 2019.


All GPS systems count time in weeks from 6th January 1980. The week number is stored as a 10-bit binary number which only allows for a maximum of 1,024 weeks before resetting itself to 0 (Zero). This rollover happened 6th April 2019 and all GPS receivers and systems using GPS Chips for both position and UTC which are 10 years old.


If it affected your GPS will show an incorrect date &/or time.



The US Department of Homeland Security has reported an error of one nano-second in the time equates to one foot of position error.


One Nano-second is one thousand -millionth of a second.
It wouldn't take much time difference/error to be a few miles off course.(one second would be 190,000 miles)

It won’t affect accuracy. If affected by the rollover issue it simply won’t get a fix. This is of course the second rollover event. We have an ancient GPS in our glider tug. At each rollover event it wouldn’t get a fix, but resetting it (clearing its almanac memory) fixed the problem.

[Alan de Enfield]

38 minutes ago, dor said:

I have an A10 Satmap - a gps device with OS maps which is mostly used by walkers.  I was one of the early adopters of this device, and I bought it in June 2008 so it is over ten years old.   It is showing the correct (UTC) time, and currently has a positional accuracy of 16 feet, which is about as good as you get without having a linked base station to compensate for the link which is how the OS use the US gps (I understand the US military get positional accuracy down to a couple of centimetres).

I have 3 of these (with UK 1:10,000 maps) Excellent devices.

When you connect it to your PC it downloads software updates which have overcome the 'roll over' problem.

[MoominPapa]

2 hours ago, MartynG said:

What date is the next crisis?

03:14:07 UTC on 19 January 2038, which is when the time in the Unix Epoch (seconds since midnight UTC on 1st Jan 1970) rolls over 2^31 and therefore the maximum that can be stored in a 32-bit signed integer. Lots of systems store the date using 32-bit integers.

 

MP.

 

[dor]

Having spent a fair chunk of my life managing a Unix system, I did, I'm afraid to say, maintain a certain smugness during the so called millennium bug period.

 

 

And in fact, it didn't affect any of my DOS-based systems either.

58 minutes ago, MoominPapa said:

03:14:07 UTC on 19 January 2038, which is when the time in the Unix Epoch (seconds since midnight UTC on 1st Jan 1970) rolls over 2^31 and therefore the maximum that can be stored in a 32-bit signed integer. Lots of systems store the date using 32-bit integers.

 

MP.

 

 

 

Having spent a fair chunk of my life managing a Unix system, I did, I'm afraid to say, maintain a certain smugness during the so called millennium bug period.

 

 

And in fact, it didn't affect any of my DOS-based systems either.

 

•  

• Quote
• Edit

---

 

 

Edited May 25, 2019 by dor
Don't ask me why it has done ithis!

[Murflynn]

 are you sure this isn't a scam?

 

this sentence doesn't make sense, and while I appreciate that US Homeland Security may be a bit of a joke, surely they can compose a simple sentence?  :

 

"This rollover happened 6th April 2019 and all GPS receivers and systems using GPS Chips for both position and UTC which are 10 years old."

[Momac]

4 minutes ago, Murflynn said:

 are you sure this isn't a scam?

I have seen this elsewhere and it seems to be a genuine issue. 

 

[Chewbacka]

Garmin state that some of their older systems will not get a software update to correct the roll over, however position is correct the date isn’t correct and the time might not be.  

 

I have a very very old garmin gps12 which indeed shows the correct location but the date is years out.

Edited May 25, 2019 by Chewbacka

[Alan de Enfield]

39 minutes ago, Murflynn said:

 are you sure this isn't a scam?

 

this sentence doesn't make sense, and while I appreciate that US Homeland Security may be a bit of a joke, surely they can compose a simple sentence?  :

 

"This rollover happened 6th April 2019 and all GPS receivers and systems using GPS Chips for both position and UTC which are 10 years old."

oops : I missed some out when typing it 

 

This rollover to 0 happened 6th April 2019 and had the potential to affect all GPS receivers and systems using GPS Chips for both position and UTC which are over 10 years old."

 

Edited May 25, 2019 by Alan de Enfield

[Wanderer Vagabond]

Curiously, and probably totally unconnected to this, I was travelling back from Leicester to Liverpool in a hire car on 7th May and between 1pm and 2pm whilst travelling along the A50 from the M1 all the way through to the M6 the satnav got itself lost and was showing the car travelling across fields with no sign of the roads we were actually on. To me I just thought it was a glitch on the set and didn't give it much thought, until I spoke to my daughter later the same day when she had been house-hunting in Oxford and her satnav had also crashed at much the same time so she had difficulty in finding the addresses that she was looking for. Coincidence? probably, but a bit odd nonetheless.

 

As far as Galileo goes, the UK aren't being stopped from using it (since anyone can), we are being stopped from controlling it since it was agreed that no third country would be given the access codes, we are going to be a third country so we are merely complying with conditions that we came up with and agreed to.

[nicknorman]

7 minutes ago, Chewbacka said:

Garmin state that some of their older systems will not get a software update to correct the roll over, however position is correct the date isn’t correct and the time might not be.  

 

I have a very very old garmin gps12 which indeed shows the correct location but the date is years out.

The GPS in our tug is a Garmin GPS100. This was the first GPS that Garmin built. Having reset it by clearing its memory, it is once again working fine with the correct date and time

[zenataomm]

This will explain why I missed the junction at Hawkesbury and only missed The Greyhound by a nanosecond. 

[reg]

4 hours ago, MartynG said:

My GPS devices are all a lot less than 10 years old. 

However this reminds me of the year 2000 thing which made loads of work for IT people . Apparently the IT people think they did a great job in avoiding a disaster. I say it was a job creation scheme.

What date is the next crisis?

Then it looks like you don't understand the genisis of the problem. 

However although the work was mundane it did pay well. 

[Murflynn]

I was walking the dogs this morning and I didn't get lost.  Don't know what all the fuss is about.

[tree monkey]

3 hours ago, MoominPapa said:

03:14:07 UTC on 19 January 2038, which is when the time in the Unix Epoch (seconds since midnight UTC on 1st Jan 1970) rolls over 2^31 and therefore the maximum that can be stored in a 32-bit signed integer. Lots of systems store the date using 32-bit integers.

 

MP.

 

I presume that's English 

[MoominPapa]

2 minutes ago, tree monkey said:

I presume that's English 

Don't worry about it. You should be drinking whisky by now.

 

MP.

 

[MtB]

13 minutes ago, MoominPapa said:

Don't worry about it. You should be drinking whisky by now.

 

MP.

 

 

Made perfect sense to me, AND I'm drinking whisky!!

 

 

[alan_fincher]

27 minutes ago, Mike the Boilerman said:

 

Made perfect sense to me, AND I'm drinking whisky!!

 

 

But that's the only reason it did make perfect sense to you!

[MtB]

6 minutes ago, alan_fincher said:

But that's the only reason it did make perfect sense to you!

 

Good whisky clarifies the mind, as any fule kno...

 

 

[tree monkey]

4 hours ago, Mike the Boilerman said:

 

Made perfect sense to me, AND I'm drinking whisky!!

 

 

It's morning and it still makes no sense