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Fenix 6X problems with elevation data on flat runs

dima1109
over 4 years ago

I've recently started running in a new place that is very flat (Phoenix) compared to where I used to run before. I'm seeing weird issues with the altimeter/elevation data. Most of my running routes have no more than 30-40 feet of elevation change according to caltopo and google maps. When I do a running activity on the watch, it would track the elevation pretty well for the first 10-15 min of a run, and then the data would suddenly get very noisy. The average elevation level would still be relatively correct, but the watch records a large number of dips and spikes, which it then adds up at the end to come up with a 500ft elevation gain for the whole activity, which is completely wrong. This only seems to happen on flat road-running routes though. When I try to go on some trails with actual elevation changes, the watch tracks those very well and has never had any significant errors. I tried doing the altimeter calibration before each run, but that doesn't seem to make a difference. Here is an example - notice how the data becomes very noisy after about 12 minutes of good tracking:

  • 0 over 4 years ago

    todays run...disabled auto calibration, barometer settings changed from auto to barometer...still not good enough. Reported gain/loss is approx x3. I had no such problems untill somwhere mid june or around 9.92-9.94 beta...  

  • 0 over 4 years ago in reply to acajic14

    And it started in the middle of the activity - is that a constant thing? Is there a time limit you're seeing this behaviour suddenly switch on?

  • 0 over 4 years ago in reply to Ɛpsilon

    From those two graphs you've posted, am I right in saying it's doing that abut 25 mins in?

  • 0 over 4 years ago in reply to acajic14

    What are you using for GPS settings (GPS, GLONASS, GALILEO)

    I ask for if you've set the barometer to barometer only then the only thing it's getting altitude from would be GPS, so do the tracks (for example) start getting worse in quality around the same time in - is there something happening where it's no basically seeking for GPS position and getting it hideously wrong?

  • 0 over 4 years ago in reply to Ɛpsilon

    In my experience, it starts getting screwed around 15-20 minutes into it pretty consistently. I used GPS+GALILEO. The weird part is that is seems to be a gain error: it’s not that the recalibration (or whatever is happening) gets the altitude or positioning wrong once during the activity, it seems to suddenly start drastically amplifying small altitude differences that it was able to attenuate or filter through earlier.  

  • 0 over 4 years ago

    Update: second run with calibration set to “at start” got me 450 feet of elevation gain on a 45-foot route, so problem still exists. Will try the “barometer” watch mode next, but that’s a bad solution because a) a 700-dollar watch should be able to tell, and b) that probably messes up activities with actual elevation changes. 

  • 0 over 4 years ago in reply to dima1109

    Sounds weird, but try the next one as say GPS+GLONASS ? See if it is GPS related? (at least partially!)

  • 0 over 4 years ago

    Hello. I have the same exact problem. I already submitted some posts, if you look for my name. You can change any setting but no way, the issue continues. it seems the problem might appear with FW9.0.

    the problem could be the air flow into the barometer holes... try to use it on the right hand, to me it worked.

    maybe it’s a design gap, or the sw is not able to manage correctly the sensor, os some devices have the barometer sensor defective?

    anyway this is unacceptable, I am sending my Fenix 6x to the Garmin support, I am very upset after such expense

  • 0 over 4 years ago

    I have tried all GPS combinations so we can tick that off... and error starts randomly between 18 - 45 min into runs. went through all of them. In only 4 runs this kind of error did not happen - three times i've put watch on my right wrist and once - I don't know if that could somehow be connected - when temperature was below 18C and less than 80% humidity. All errors happened at higher temperatures / humidity...

  • 0 over 4 years ago in reply to paolo_costantini

    If it was air flow, I'd expect the issue to follow your cadence, as you swing your arms then you'd get positive pressure then negative pressure?

    REALLY odd thing to try, in case you haven't? Wash your watch gently in case of debris? I'll be honest, looking at the graph there's no obvious cyclicality toit....