New 2021 GPS accuracy issue affecting some Garmin, Suunto and other GPS devices


#Just a super quick article to provide a little bit of context on an issue some (but not all) see where your saved GPS track is off by more than a hundred yards or more. #Usually the pattern of your route is correct, but it can be moved to one side or the other. #However, in many cases, at the end of the workout, it adjusts itself. #In other words, it’s mostly a one-off problem.
#Much of the problem seems to be affecting companies that use the #Sony GPS chipset in their devices, which are basically all new #Garmin devices in recent years, most new #Suunto devices in recent years, all #Polar devices in recent years. , all COROS devices, the #Wahoo RIVAL, etc. #More or less everyone except #Apple.

#Very rough list of impacted devices (I’m missing a ton here, these are just the most popular)

– COROS GPS watches (you have to check the original rhythm, however)
– #Garmin #Forerunner 45/245/745/945 / #Fenix ​​6 / MARQ / #Vivoactive 3/4 / #Venu
– #Garmin #Edge 130 #Plus 530/830/1030 #Plus
– #Polar #Vantage V / M / V2, #Grit X, #Ignite
– #Suunto 5 and #Suunto 9
– #Wahoo RIVAL

#Again, I’m missing a boat here, but it’s the big bills that come to mind.

#All of these companies have switched to the #Sony GPS chipset since around 2018, with #Polar and #Suunto initially on board, followed quickly by #Garmin, COROS, etc. The #Sony GPS chipset is widely used by these companies due to the power savings which allows for longer battery life.

#But – that’s anything but the point, not the cause of the problem. The issue is with the ephemeris data file, also known as the #Extended #Prediction #Orbit (EPO) or #Connected #Predictive #Ephemeris (CPE) file. #Or just the satellite pre-cache file. #This is the file that is delivered to your device on a frequent basis (usually every few days). #This file allows your watch to find GPS satellites almost instantly when you go out. #It’s basically a cheat sheet showing where the satellites are for the next few days, or up to a week or so.

#Your watch or bike computer automatically obtains this file via #Bluetooth #Smart from your phone, #WiFi or USB, depending on how you connect your watch. #Most companies deliver it every time your watch syncs and needs a new version. #So on your end, you never do anything – it just happens in the background.

#At the moment, the data in this file is in error, and therefore the data used by your watch during these first few minutes is also in error, resulting in offsets. #You can see an example below, from a DCR reader:


#And another:


#As the watch maintains its connection to the GPS satellites throughout the workout, it will usually correct itself because it pulls the updated data from above. #Most people report that resolve either at the end of the workout or at the next workout. #You can see it here from another DCR player:

#To help resolve this issue, you can just stick your bike watch / computer outside and let it record one hour of training, then throw it away after that. #He will have received the necessary satellite information to probably correct himself.

#But it will not impact everyone. #For example, I tried today with two #Sony-based watches (#Garmin FR745 and FR945) to get it to trace an incorrect trail – and it wouldn’t. I suspect this is because in my case the watch was repeatedly bumped while playing with my kids yesterday and today so I guess it had already downloaded again what it needed to be correct out of the door. I also tried with two non-Sony chipsets (#Fenix ​​5S and #Apple #Watch SE), and I didn’t see any issues either.

#Speaking to #Garmin today, they are working on a fix for the problemwhat they probably believe is that they are simply updating the satellite pre-cache data from the server, which in turn will capture your watch as it always does. #But first, they (and others) strive to figure out what exactly is wrong with the data that’s causing it.

#While chatting with another industry person dealing with the issue, they noted that technically 2020 is 53 weeks, and this is week 53. #As such, the suspicious #Sony data file issue could actually be related to this complexity.

#You see … just when you thought you had escaped 2020, he’s still waiting for you at the start of your run.

#With that – thanks for reading!


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