Just a super quick message to give a little bit of context about an issue that some people (but not all) see where your GPS track is being compensated by more than a hundred yards or more. In general, the pattern of your route is correct, but it can be moved to one side or the other. In many cases, however, after the workout, it sorts itself out. In other words, it’s mostly a one-time issue.
It seems that the issue is largely influenced by companies that are using the Sony GPS chipset in their devices, which is basically all the new Garmin devices in the last few years, most new Suunto devices in the last few years, all Polar devices over the past few years all COROS devices, the Wahoo RIVAL, and more. More or less everyone except Apple.
Very rough list of devices affected (I miss a ton here, it’s just the most popular)
– COROS GPS watches (must check the original tempo)
– 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 miss a boatload here, but these are the big tickets on top of my head.
All of these companies have switched to the Sony GPS chipset since about 2018, with Polar and Suunto initially jumping on board, followed quickly by Garmin, COROS and more. The Sony GPS chipset is widely used by these companies because of the power saving that provides longer battery life.
But that’s all but the point, and not the cause of the problem. The issue has to do with the ephemeris data file, also called the EPO (Extended Prediction Orbit) file or Connected Predictive Ephemeris (CPE). Or simply the satellite-before-cache file. This is the file that is regularly delivered to your device (usually every few days). This file lets you watch GPS satellites almost instantly when you go outside. It’s basically a cheat sheet where the satellites are for the next few days, or up to a week or so.
Your watch or bike computer automatically gets this file via Bluetooth Smart from your phone, WiFi or USB, depending on how you connect your watch. Most businesses deliver it when your watch is in sync and needs a new version. For your part, you never do anything – it just happens quietly in the background.
At the moment, the data in this file is incorrect, and so the data that your watch uses for the first few minutes is also incorrect – leading to offsetting. You can see an example of this below from a DCR reader:
As the watch maintains its connection to GPS satellites over the duration of the workout, it will generally correct itself again if it retrieves updated data from above. Most people report that it will happen solves himself at the end of the workout or the next workout. You can see it here from another DCR reader:
Same here – identical bugs at the starting point on my wife’s Fenix 6X Pro and Forerunner 45S, then they sort themselves out – I walked, she ran, so my route is more accurate because I had more time to get a to get a solution, I think … pic.twitter.com/tZ4ysgYPtW
– ac72 (@ ac72) 2 January 2021
To solve it, you can simply put your watch / bike computer outside and have an hour-long workout recorded and then throw it away. It will receive the necessary satellite information to likely correct itself.
But it will not affect everyone. For example, today with two watches on Sony (Garmin FR745 and FR945) I tried to set it down incorrectly – and it would not work. I suspect it’s because in my case the clock was knocked out a few times while I was playing with my kids yesterday and today, so my guess is that it had already downloaded again what was needed to be correct out of the gate. I also tried with two non-Sony chipsets (Fenix 5S and Apple Watch SE), and also saw no problems.
In conversation with Garmin today, they are working on a solution to the problem, which they say is likely to be just updating the satellite pre-cache data from the server, which in turn grabs you, just like always. But first they (and others) are figuring out what exactly is wrong with the data it causes.
In a conversation with another person in the industry, they noted that 2020 technically had 53 weeks, and that is the 53rd week. As such, the suspicious issue with Sony’s data file may actually be related to its complexity.
See… just when you thought you should escape from 2020, it’s still waiting for you at the beginning of your run.
With that – thanks for reading!