Firmware 20 awful GPS accuracy on Fenix 5

Since I upgraded the Firmware from from 19.1 to 20, I get the most terrible GPS accuracy ever on my Fenix 5 Saphire. On a recent hiking tour I had about 15km on my display while my wife with the Fenix 5S Plus got about 12,5 for the same tour. Most of the time, my track was way off the street, many loops and jumps where there were in fact only a 180 degree turn of the street. When standing still during brakes the distance increased constantly as if I would walk around. During a run yesterday, it showed a pace of 5:45 at the first 500 m although I was running about 4:45-4:50. The watch is absolutely unusable. Considering updating to Forerunner 735 or 745 now. Any better ideas? How can I downgrade to 19.1?

Does anybody know if there.was also a GPS Software Update as Part of the Firmware 20? My watch shows GPS version 2.6.

Any help is appreciated!

Jens

0 reittila over 4 years ago in reply to Tschens

Done that. No problems with hiking GPS accuracy either.

0 Tschens over 4 years ago in reply to reittila

If you have the Fenix series: Just start the watch in hiking mode, lay it down somewhere and see what happens. You will see a track increasing about 10 meters per minute, although the watch is just lying there. No problem with Fenix Plus Series.

0 subra over 4 years ago in reply to Tschens

Tschens said:
Just start the watch in hiking mode, lay it down somewhere and see what happens. You will see a track increasing about 10 meters per minute, although the watch is just lying there. No problem with Fenix Plus Series.

This is well known and it's called GPS Drift

https://support.garmin.com/en-US/?faq=cs2qejGova0TocKbcwWQx9

It's simply the continuous accumulation of the GPS position error.

Please have a look at the pic Example 1: GPS Indoors on this page to see what is going on in this case.

0 Tschens over 4 years ago in reply to subra

I know what GPS drift is. But there is a huuuuge difference between Fenix 5 and Fenix 5 Plus:

Fenix 5, put somwhere in my garden, blue sky, no clouds, no trees. After 10 min it shows 100m total distance. Continuously increasing with aproximately 10m/min.

Fenix 5 PLUS, lying next to it: 0 m after 10 min.

I checked many older tracks, and it seems that this is a general problem of Fenix 5 and not related to the latest firmware version 20. I noticed it because I've been hiking a lot lately. As mentioned earlier, if you run or ride the bike, this drift is neglectable. But the drift has an extreme impact when hiking, the track looks awful in comparison to the track from Fenix 5 plus or to my good old Forerunner 110. By the way: the same is true for the pace during the firs 100-200 m of each kilometer during running. Completely wrong. The second part of each kilometer is quite OK, and the final pace is more or less correct. Total distance is OK.

After much research in different discussion groups I am quite sure that this is a general "Fenix 5 Problem", and not a specific one only for my personal watch. I consider to exchange it. Still searching for an alternative. I must admit that I was aware of the fact that Fenix 5 doesnt always measure distances and paces very precisely. But how wrong the measurement is, I only noticed since I got the direct comparison with the other watches.

Edit: I just came back from a hike through a canyon through the woods with my wife. While she has 4,4 km and a nice track on her Fenix 5S, I got 5,4 km on my Fenix 5 for the same route - and dont ask how the track looks like. Not a egrat result for a 600 Euro watch.

Regards,

Jens

0 subra over 4 years ago in reply to Tschens

Tschens said:
Fenix 5, put somwhere in my garden, blue sky, no clouds, no trees. After 10 min it shows 100m total distance. Continuously increasing with aproximately 10m/min.

Fenix 5 PLUS, lying next to it: 0 m after 10 min.

Be sure that the setting of Auto Pause is identical for F5 and F5+. Garmin recommends to switch Auto Pause to ON, especially if hiking with some stops on the way (see the link above).

Tschens said:
As mentioned earlier, if you run or ride the bike, this drift is neglectable.

Yes, that's right. According Garmin the absolute max. position error is 3m and of course the relative position error depends on the speed of moving.

Tschens said:
By the way: the same is true for the pace during the firs 100-200 m of each kilometer during running. Completely wrong. The second part of each kilometer is quite OK, and the final pace is more or less correct. Total distance is OK.

Because of the position error the track points must be filtered and smoothed and I'm sure that this is done by SW by default. May be it's a moving average of ~5-10s. If in an activity there is a sharp change in direction or speed, there is always some delay in the response of the corrected pace at the watch. If you use Auto Lap every 1km it may be that the smoothing isn't countinuously, but rather every lap starts again a new smoothing process. But 100-200m seems much to long for the correction.

0 Tschens over 4 years ago in reply to subra

Thx subra for your input. Both devices have autopause switched off. From another thread I know that Fenix 5 often has problems with autopause switched on since the GPS is so inaccurate that it either pauses without reason or it doesn’t realize the restart of a hiking tour. Never tried autopause myself but for me this doesn’t make sense as a workaround. Fenix 5 Plus shows that it is possible and accurate without autopause. Seems to be another GPS chip wich is more advanced.