Just a super quick post to provide some context on an issue that some (but not all) see where your recorded GPS track is offset by more than a hundred meters or more. In general, the pattern of the route is correct, but it can be shifted to one side or the other. However, in many cases, once the session is over, it is resolved. In other words, it is mostly a one-time problem.
The problem seems to greatly affect companies that take advantage of Sony’s 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 CHORUS devices, the Wahoo RIVAL and more. More or less everyone except Apple.
Very rough list of affected devices (I’m missing a ton here, only the most popular)
– COROS everything except the original COROS Pace
– Garmin Forerunner 45/245/945 / Fenix 5 Plus / Fenix 6 / MARQ / Vivoactive 3/4 / Venu
Garmin Edge 130/130 Plus 530/830/1030 Plus
Polar Vantage V / M / V2, Grit X
– Suunto 5 and Suunto 9
– Wahoo RIVAL
Again, I miss a ship load here, but this is the big ticket from my top.
All of these companies have switched to Sony’s GPS chipset since around 2018, with Polar and Suunto initially jumping on board, quickly followed by Garmin, COROS and more. These companies make extensive use of the Sony GPS chipset because of the power savings it provides with longer battery life.
But, that’s all apart from the point, not the cause of the problem. The problem has to do with the ephemeris data file, also called EPO (Extended Prediction Orbit) file or Connected Predictive Ephemeris (CPE). Or just the satellite cache file. This is the file that is delivered to your device frequently (usually every few days). This file is what makes the watch find GPS satellites almost instantly when you go outside. It is basically a sheet of deception where the satellites are in the next few days, or up to a week or so.
Your watch or bike computer receives this file automatically via Bluetooth Smart from your phone, WiFi, or USB, depending on how you connect the watch. Most companies deliver it every time the clock syncs and needs a new version. So, by your side, never do anything: go quietly to the bottom.
Right now, the data in this file is incorrect and therefore the data used by the watch during the first few minutes is also incorrect, which causes offsets. You can see an example of this below from a DCR reader:
While the watch maintains its connection with GPS satellites for the duration of the training, it will usually be corrected again while pulling updated data from above. Most people report that they will be resolved at the end of training or at the next workout. You can see it here from another DCR reader:
Same here: identical errors at the starting point of my Fenix 6X Pro and my wife’s Forerunner 45S, and then resolved: I walked, ran, so my route is more accurate as I guess that I had more time to fix it … pic.twitter.com/tZ4ysgYPtW
– ac72 (@ ac72) January 2, 2021
To help resolve this, You can put the bike and watch computer outside and let it record an hour of training and then discard it.. You will have received the satellite information you need to probably correct yourself.
But it will not affect everyone. For example, today I tried with two Sony-based watches (Garmin FR745 and FR945) to get it to set a wrong track, and it wouldn’t. I suspect this is because, in my case, the clock had been struck a few times while I was playing with my kids yesterday and today, so I guess I had already re-downloaded what I needed to be right through the door . I also tried with two chipsets that weren’t from Sony (Fenix 5S and Apple Watch SE), and I didn’t see any issues either.
Speaking with Garmin today, they are working on a solution to the problem, who believe that they are only likely to update the satellite cache data from the server, which in turn will take the clock as usual. But first, they (and others) are working to figure out what exactly is wrong with the data causing this.
Talking to another person in the industry who was dealing with the issue, they pointed out that technically 2020 was 53 weeks, and this is the 53rd week. As such, the suspicious problem with Sony data files could be really related to this complexity.
Look … just when you thought you had escaped 2020, it’s still there waiting for you at the beginning of your career.
With that, thanks for reading!