Just a super quick post to provide some context about an issue that some (but not all) people are seeing where their recorded GPS track is shifted by more than a hundred meters or more. In general, your route pattern is correct, but it can be shifted to one side or the other. However, in many cases, at the end of training, he calls himself. In other words, it is mainly a unique problem.
The problem appears to be largely affecting companies that take advantage of Sony’s GPS chipset on their devices, basically all the new Garmin devices in recent years, most new Suunto devices in recent years, all Polar devices in recent years, all devices COROS, the Wahoo RIVAL and much more. More or less everyone except Apple.
Very approximate list of impacted devices (I’m losing a ton here, these are just the most popular)
– COROS GPS watches (however, it is necessary to recheck the original Pace)
– 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 load here, but these are the most expensive right away.
All of these companies have switched to Sony’s GPS chipset since around 2018, with Polar and Suunto initially shipping, followed quickly by Garmin, COROS and more. Sony’s GPS chipset is widely used by these companies due to the energy savings that provide longer battery life.
But – this is beyond the point, and it is not the cause of the problem. The problem has to do with the ephemeris data file, also called the EPO (Extended Prediction Orbit) or Connected Predictive Ephemeris (CPE) file. Or simply the satellite’s pre-cache file. This is the file that is delivered to your device frequently (usually every few days). This file is what makes your watch find GPS satellites almost instantly when you leave the house. It’s basically a tip sheet of where the satellites will be in the next few days, or even a week or more.
Your watch or bike computer automatically obtains this file via Bluetooth Smart from your phone, WiFi or USB, depending on how you connect the watch. Most companies offer this whenever your watch is synchronized and needs a new version. So, on your side, you never do anything – it just happens quietly in the background.
At the moment, the data in this file is wrong and therefore the data that your watch uses during the first few minutes is also wrong – leading to shifts. You can see an example of this below, from a DCR reader:
As the watch maintains its connection to GPS satellites throughout training, will usually correct itself as it pulls the updated data from the top. Most people are reporting that resolve yourself at the end of training or the next training. You can see this here on another DCR reader:
The same here – identical errors at the starting point on my Fenix 6X Pro and my wife’s Forerunner 45S, so they resolve themselves – I walked, she ran, so my route is more accurate because I had more time to fix, I think … pic.twitter.com/tZ4ysgYPtW
– ac72 (@ ac72) January 2, 2021
To help resolve this, you can just put your bike watch / computer outside and let it record an hour of training and then discard it after that. He will have received the necessary satellite information to probably correct himself.
But it will not affect everyone. For example, I tried two Sony watches today (Garmin FR745 and FR945) to get him to set an incorrect track – and he wouldn’t. I suspect that it is because, in my case, the clock was struck a few times while playing with my children yesterday and today, so I think he had already downloaded again what needed to be corrected from the beginning. I also tried it with two non-Sony chipsets (Fenix 5S and Apple Watch SE), and I also found no problem.
When talking to Garmin today, they are working on a solution to the problem, which they believe will probably be that they just update the pre-cache data from the server satellite, which in turn your watch will capture as it always does. But first they (and others) are working to find out what exactly is wrong with the data that is causing it.
When talking to someone in the industry who is dealing with the problem, they noted that, technically, 2020 was 53 weeks old, and this is the 53rd week. Thus, the problem with Sony’s suspicious data file may actually be linked to this complexity.
See … just when you thought you escaped 2020, it’s still there waiting for you at the start of your run.
With that – thanks for reading!