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Fenix 6X unexpected behavior in Open Water Activity GPS distance as soon as I started the activity

Silvio Pola
10 months ago

I have a Garmin Fenix 6X Pro Sapphire updated to the latest released firmware 27.00.
This summer I started my open water activities but I encountered a very strange behavior in the "open water" activity that made me think something needs to be fixed.
These are the step to reproduce the issue:
1) Open the "Open water activity" activity in an open and dry situation -> no physical obstacles for satellites.
2) Wait the GPS connection and wait also a bit more
3) Without make a move -> Start the activity.

I'm absolutely immobile but the distance counter starts counting more or less 1 meter per second.
I create a video to better explain this experience:

Youtube - Garmin Fenix 6X - GPS open waters

At first I thought I have a problem in my watch, but yesterday I saw that my friend with the same model/firmware has the same problem.

I read several posts and suggestions for settings -> now I have GPS + GALILEO and recording every 1 second, but I also tried the other choices.

I read about the "Drift Effect" but really I can't undestand why my GPS when I'm absolutely still without any problem in GPS connection and I start the activity have to stat to count distance by itself. In this particular case there is nothing to compensate like GPS disconnection or "arm rotation effect" ... nothing, I cant understand :-(
This doesn't happen in running activity for example.

Are you sure it is not possible to improve/correct this Open Water activity ?
Although I don't understand why the GPS behaves this way, would it be possible to improve the app by involving also other sensors on the watch as probably happens for other activities ?

Thank you,
Silvio



  • 0 8 months ago in reply to Silvio Pola

    Bluefish I just only would like to deeply understand how to behave these devices and if something could be improved, I love Open Water and, if possible, I hope to have the best experience as possible with my Garmin watch (I love it too).
    For me this behaviours are not so clear.

    I made 3 different test, 4 minutes of tracks where I stopped and restarted activity in this way:
    Test1 -> no pause
    Test2 -> pause/restart every 60 seconds
    Test3 -> pause/restart every 20 seconds

    In all these test I remained still in the same position with GPS always connected (GPS + GALILEO)

    These are these Activity from Connect platform:


    These are the distance calculated with TCX/GPX/KML data:

    Test 1 -> Total distace: 29.44m


    Test 2 -> Total distace: 1.1 m


    Test3 -> 0.97 m


    From what i see:
    Test1 ->
    Real distance: 0
    GPX/TCX/KML Distance: 29.44 m
    Open Water Activity calculated distance: 41 m

    Test2 ->
    Real distance: 0
    GPX/TCX/KML Distance: 1.1 m
    Open Water Activity calculated distance: 164 m

    Test3 ->
    Real distance: 0
    GPX/TCX/KML Distance: 0.97 m
    Open Water Activity calculated distance: 205 m

    I would like to understand why it seems that the error on the distance is dependant to how many times I pause and restart the activity ?
    Is it started any filter (kalman or others) every time I pause and restarted the activity that adds errors in the beginning ?
    Is it the best approach to this problem ? Is really not possible to improve this ?

    Another question ... Garmin measure the distance in meters when it assumes an error (drift) that is higher than 1 meter, It seems strange (error higher than the accuracy), for example Running uses the scale 0.00 km so the accuracy is 10 meters, could it be better to cut off drift errors (with a more efficient filtering algorithm) ?

    Just to add more observations, just today i made a test with a guy with a Fenix 7X Pro Solar, I'm sure it doesn't have this problem  the same of one of my friend with the same Solar model (I linked the video in one of the post before), another friend instead, with a Fenix 7X Pro (Not solar), shows this issue. (all with the same 17.28 software version).

    Really not clear.

    Just ro compare the differences between Open Water and Running for example, same watch, same posizion, from connect platform:



    Has you can see
    - The running activity cut off the drift and the calculated distance remains zero, even if you pause and restart the activity
    - The open water calculate a wrong distance and is not able to manage drift as the running one moreover if you pause and restart activity the distance increase more and more , see the previuous tests

    For info the GPX/TXC/KML distance in the 3 test before are 
    - Test - Run - 2 min - pause every 20 secs: 6.71 m
    - Test - Open Water Swim - 2 min: 9.38 m
    - Test - Run - 2min: 2.99 m


    Thank you

  • 0 8 months ago in reply to Silvio Pola

    In the previous post a collected a lot of observations ... I really hope Garmin take care of them and improve the situation.