The GPS accuracy issue has been impacting Garmin, Suunto and Polar watches over the past week

GPS wrong

In the last 7 days there was a a crowd of people Certain GPS watches experience accuracy issues, causing the GPS track to deviate from reality (usually in a specific direction). This often results in GPS tracks where the visual pattern might be correctbut it is not in the right place. That means it’s as if someone Your route slightly shifted to the sidethat ultimately let you walk on water, or walk through buildings. Alternatively, it could just have or be weird gaps downright dumpster fire wrong. In theory, the problem should have been fixed by last night.

This The problem particularly affected those with Sony GPS chipsetswhich is essentially a repetition of a problem that occurred 18 months ago that was far broader (for various reasons). The issue first emerged over the New Year’s holiday weekend and was the first time these companies saw it, significantly slowing down the response rate (and also increasing the number of people affected).

This time the impact was certainly measurable (as my inbox can attest) but the duration was more limited. It first affected last Tuesday/Wednesday (June 28/29), then again last weekend and early in the week (July 1-July 5). The number of watches affected here is huge and essentially every Garmin watch that has come out in recent years (but not most in 2022 as they use a different chipset), as well as all Suunto/Polar watches and theoretically all COROS watches except the Vertix 2 (although I haven’t seen any COROS reports so maybe they put a different filter in place).

GPS wrong

Roughly speaking these would be the following watches (plus the 29 million variants of these watches that Garmin has):

– Garmin Forerunner 45/245/745/945/945 LTE/Fenix ​​6/MARQ/Vivoactive 3/4/Venu
– Garmin Edge 130 Plus, Edge 530/830/1030 Plus
– Garmin Enduro watch
– Garmin Instinct Series 1 & Series 2 watches
– Polar Vantage, Grit and Pacer series watches
– Suunto 5/5 Peak and Suunto 9/9 Peak

Again, the above list is not all-inclusive. Countless other watches are affected, most notably from Garmin, which uses near-identical watches in various other fields such as marine, golf, and aviation. Additionally, this would theoretically affect the Wahoo RIVAL & COROS watches (other than the Vertix 2), although I can’t find any instances of people having problems there. That means they’ve either been reported or they’ve implemented damage controls.

Meanwhile the Garmin and COROS watches are not affected:

Garmin Fenix ​​7 & Tactix 7 series
Garmin EPIX series
Garmin Forerunner 255 series
Garmin Forerunner 955 series
Garmin Edge 1040 series
CHORUS Vertix 2

All of these watches use a different multi-band chipset from MediaTek/Airoha, which is not affected here.

The problem has to do with that Ephemeris data file, also known as an Extended Prediction Orbit (EPO) file or Connected Predictive Ephemeris (CPE). Or just the satellite pre-cache file. This is the file that is sent to your device on a regular basis (usually every few days). This file allows your watch to find GPS satellites almost instantly when you go outside. It’s basically a cheat sheet of where the satellites are in the next few days or up to a week or so.

Your watch or bike computer will automatically receive this file via Bluetooth Smart from your phone, WiFi or USB depending on how you connect your watch. Most companies ship it whenever your watch syncs and needs a new version. So you never do anything on your part – it just happens quietly in the background. The data in that file was incorrect, and therefore the data your watch uses for the first few minutes is also incorrect – leading to the offsets.

That The good news is that the solution is simple: Just Sync your clock to get an updated copy. For example, Garmin says that if your watch has been connected to your phone since last night, a new EPO file should/will be downloaded, which will fix the problem. Garmin also says they have locks in place to ensure this doesn’t happen again. However, they also said that 18 months ago, so I’m assuming whatever Sony did this time in a new and special way that wasn’t the same as last time.

With that, hopefully it helps people understand what’s going on and how to fix it.

Thank you for reading!

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