GPS Week Rollover April 2019 - May affect older (pre-2010) GPS devices

CYYJ

CYYJ

Michael
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Toronto & Zürich
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None any more.
Hello All:

When the Navstar GPS constellation (operated by the US Military) went live in January of 1980, week numbers used by the satellites were based on a 10 bit parameter. This meant that 1024 'week numbers' were available before the numbering system rolled over and began counting up from 0 again.

The first epoch of 1024 week numbers ended in August of 1999 (1024 weeks after January 1980). I well remember the problems that happened with un-patched aviation GPS devices at that time - GPS didn't really take hold in the motorcycle and automotive community until about 2001. If the device wasn't 'patched' with updated software before the end of that first epoch, it simply stopped working.

Another 1024 weeks have nearly passed since then - the second epoch of week numbers will reach 1024 and roll over again to 0 in April of 2019.

If you use a GPS device that was manufactured after 2010, you probably don't need to worry. Beginning in 2010, most manufacturers began manufacturing devices that used a 13 bit parameter for week numbers, meaning that they won't be affected by a week number rollover until 2057 - long after the owner has turned to dust.

But, if you are using an older GPS device - one manufactured during or before 2010 - take a moment to check and see if there is a software update for your device available from the manufacturer. The software update will ensure that your device continues to work correctly after the second GPS week number epoch ends on April 6 2019.

Further information about the week number concept is available from the US Government's GPS website, https://www.gps.gov/

Michael
 
Thanks! Good info. Software on my 550 is as up to date as it can be so hopefully it doesn't play dead soon.
 
I am going to guess that any Garmin Zumo product with a number higher than 300 probably uses the 13 bit week number system and should be unaffected.

The GPS units that I think are at risk are all of the older monochrome ones (GPS V, etc.) and any unit with 'StreetPilot' in the name, because they were all released prior to 2010.

Michael
 
My Zumo 550 is post 300 series but it also pre-dates 2008. I acquired it in early 2008 so it was probably manufactured in 2007 sometime. Based on that I don't know if it would be affected or not? Within the past few weeks I did an update check on Garmin's site and there were no software updates. I hope that that means I am good to go.
 
Just curious, does anybody know why a GPS receiver counts weeks in the first place? Seems a bit odd.
 
Well, isn't THAT just jim dandy! I have a Garmin Nuvi 785T, bought in October 2009 and it isn't going to work come April?? Kinda need it for a trip in June!

To Andrew - I wanted to buy and load a new North American map - my last map upgrade was in 2015, but Garmin does not support this unit for new maps now, so I imagine that is why you also found no updates available. Simply not enough memory space in these old units, as I was told by Garmin support.

To Michael - will the unit simply stop working, or does it let you carry on a bit, then leave you stranded without guidance at some point? How do they fail? Thanks.
 
Forest;
What I meant is that there are currently no firmware or software updates available that are directly related to operating the receiver. There is currently a map update available for my 550- I just haven't down-loaded it as of yet. The maps have not fit on the internal memory for many years. I have long since been putting them on an SD card.
 
dwalby said:
...does anybody know why a GPS receiver counts weeks in the first place?
Click to expand...
It's kind of a complex explanation, but the gist of it is this: The receiver determines its position by measuring the time it takes for signals to arrive from the satellites. To make this calculation, the receiver needs to know where the satellites are. The satellites are not stationery, they orbit the earth. For that reason, the receiver needs to download what you could call a 'timetable' or 'schedule' of where the satellites will be at any given time in the future (the proper name for this 'timetable' or 'schedule' is the almanac).

The almanac tells the receiver approximately where the satellites are (or will be). In order to get an accurate position fix, the receiver needs to know the location of the satellites within 1 meter (1 yard), as well as any information affecting the health or (planned) position of the satellite. To do this the receiver downloads additional information for each satellite, known as the ephemeris.

But... there are tiny differences between what we think of as being a week (7 days of 24 hours consisting of 60 minutes of 60 seconds each) and what a week actually is, based on rotation of the earth. There's about a one-second difference every 6 to 18 months between the actual rotation of the earth and the 7 / 24 / 60 / 60 mathematical assumption. Periodically, 'leap seconds' are inserted to compensate for this difference.

For the above reasons, the receiver needs to know the exact (very precise) time and date. The week number is used to determine the date.

Michael
 
CYYJ said:
I well remember the problems that happened with un-patched aviation GPS devices at that time -
Click to expand...

Michael - will the unit simply stop working, or does it let you carry on a bit, then leave you stranded without guidance at some point? How do they fail? Thanks.
 
If I recall correctly (it was 19 years ago), the un-patched aviation panel mount units simply could not determine their position.

Back then, before the interweb brought us 'online updates' and stuff like that, we had to order a chip card from the manufacturer and stuff the chip into the device. I recall two aircraft were without GPS functionality for about 10 days, which is how long it took us to get a chip sent from Europe to the site where the aircraft were in Africa.

What I do remember well was all the "old greybeard" pilots fighting over who would get to fly the GPS-less plane... so they could demonstrate their dead-reckoning and map reading skills to the much younger co-pilots. It was really quite funny. The old guys (they were the same age I am now) were not very happy when the software update finally arrived and they had to go back to "following the magenta line".

Anyway, concerning automotive & motorcycle navigation units, I am pretty sure that if owners just hook their units up to their computer and ensure that they have the most recent version of the firmware for the device installed (even if the most recent version of the firmware is 6 years old), the unit should continue to work OK beyond the April 2019 week number rollover.

For those who have Garmin units, download the Garmin Express application - it checks for firmware updates and is super-easy to use.

For those who have TomTom units, go to this page of TomTom's website.

Michael
 
Well, that was odd. I had only been to Garmin Express just a couple of weeks ago and there were no software updates, or maps, showing as available to me. Just now, I went there again and I did get a software update, which took less than five seconds to complete, but still no maps updates. Maybe that software update was to alter this week numbering thing. Guess I'll find out in April.
 
13-bit should put the rollover closer to 2157. And GPS units made as early as late 1999 may be immune to the upcoming rollover. Forget updates and firmware patches. Play it safe and get new kit. You know you want one.

cf-lg-f084c725-d1b1-4c4a-912b-c9574fa365e3.jpg
 
Bush said:
Well, that was odd. I had only been to Garmin Express just a couple of weeks ago and there were no software updates, or maps, showing as available to me. Just now, I went there again and I did get a software update, which took less than five seconds to complete, but still no maps updates. Maybe that software update was to alter this week numbering thing. Guess I'll find out in April.
Click to expand...
Two weeks ago I ran an update on my Garmin and it only did a map update I ran Garmin Express last night to update my gps' and they both had a software update
 
CYYJ said:
Hello All:

When the Navstar GPS constellation (operated by the US Military) went live in January of 1980, week numbers used by the satellites were based on a 10 bit parameter. This meant that 1024 'week numbers' were available before the numbering system rolled over and began counting up from 0 again.

The first epoch of 1024 week numbers ended in August of 1999 (1024 weeks after January 1980). I well remember the problems that happened with un-patched aviation GPS devices at that time - GPS didn't really take hold in the motorcycle and automotive community until about 2001. If the device wasn't 'patched' with updated software before the end of that first epoch, it simply stopped working.

Another 1024 weeks have nearly passed since then - the second epoch of week numbers will reach 1024 and roll over again to 0 in April of 2019.

If you use a GPS device that was manufactured after 2010, you probably don't need to worry. Beginning in 2010, most manufacturers began manufacturing devices that used a 13 bit parameter for week numbers, meaning that they won't be affected by a week number rollover until 2057 - long after the owner has turned to dust.

But, if you are using an older GPS device - one manufactured during or before 2010 - take a moment to check and see if there is a software update for your device available from the manufacturer. The software update will ensure that your device continues to work correctly after the second GPS week number epoch ends on April 6 2019.

Further information about the week number concept is available from the US Government's GPS website, https://www.gps.gov/

Michael
Click to expand...

Thanks for the info, very informative.

Strip
 
Tom Tom says they no longer support updates for my 2006 720... it will be interesting to see when April rolls around and I have a new waterproof GPS on the way anyway.
I love when they say lifetime support and maps while in the small print tell you that the lifetime is the average lifetime of the device. That really means they are going to cut you loose in 5-8 years.
 
So if someone is going to invest in a unit soon.....me.... What unit do you guys recommend? I’m a big fan of eBay so maybe some used choices from the past few years?
 
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