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Consistent single altitude drop during the training sessions

The Enabler
over 2 years ago

I use ForeRunner 745 and I noticed that for the past 2-3 weeks, unless I'm doing an absolutely flat run (along the beach), during each of the training sessions there is a moment when the altitude suddenly drops 30-100m and then it stays there and it's wrong so I have to recalibrate. I have Auto Calibration on and sensor is set to Auto.

I run with a friend who uses Fenix 6 with the identical settings and there are no problems with their device.

Is that normal? Expected? What should I try to fix it?

  • 0 over 2 years ago in reply to lucab

    Hi lucab,

    mine is the Rev.B

  • 0 over 2 years ago in reply to Garmin-Kevin

    1 - Yes

    2 - Yes

    3 - USA

    I don't get the elevation jump on every outdoor run, but it does show up frequently.  Most recent runs with the jump were Oct 4 and 10.

  • 0 over 2 years ago in reply to Garmin-Kevin
    1.  Yes
    2.  Yes
    3.  Ireland

    Also doesn't happen every time, but at least 50%.  And for those who asked Rev A (007 version).

  • 0 over 2 years ago in reply to Conor.N

    This 300m jump is from yesterday's (8 Nov) run.  Standing around between reps, session was at sea level.

  • 0 over 1 year ago

    I received an exchange/RMA watch yesterday and did a first (albeit short) run with it and the issue did not appear. I will keep on monitoring if it reappears or if there is indeed a hardware-related component to this problem, i.e. that it does not occur in certain batches/revisions.

  • 0 over 1 year ago in reply to lucab

    Hi, @lucab I went through my activities, and unfortunately I can't confirm that it happens during notifications, I run the same sections and the error appears differently...

    But what's interesting, if I didn't miss it, it's always only once per activity. Although I have many notifications during the activity. That's weird.

    If it was related to the barometer, then the pressure changes would be about 1hPa per 10m height. Interestingly, after that mistake, the wrong height remains there, even after the activity ends. That probably rules out that the error happened due to a GPS reload, in which case the altitude should be ok, right?

    L. 

  • 0 over 1 year ago in reply to 9824669

    Yes - please keep us posted! I am skeptical about this being a hardware problem.

    I think since normally people seem to be getting an elevation drop, they do not realize it when looking at their post-activity-stats (usually only look at meters climbed, right?). I mean how would you explain that all of our watches worked perfectly fine until around software update 11 and then this thread with many people having the same problem begins? Before this, I could not be happier with the 745 altitude/elevation exactness (during activity).

    My conspiracy theory is that Garmin merged/consolidated the updates file-packages between the 945 and 745 starting with release at 10.40 or 11.03 to being the same for both. And when they merged these, they did not account for differences in the hardware or the fact the 945 has built-in maps - which I believe to be the cause.

    The problem is not every run, but 50% I would say.

    FYI - I have a rev. A product.

  • 0 over 1 year ago

     and @JS thank you both for your latest replies.

    In my case, the problem occurs in 90% of cases. 10/15 minutes walks may not get affected, but 30m runs usually do. On longer activities, the chance is 99%. And I also do confirm the elevation drop/jump is only one per activity and then persists also once the activity has been saved.

    I'm really not a GPS expert to make assumptions about which should be the root cause of the problem. However, I do agree it must be a software issue rather than a hardware one. What really bugs me is that we've all been told the problem seems to be affecting just a small group of users. That's simply hard to believe - yes we're just a small bunch of people complaining about it on this forum, but the problem is well spread. The majority of users just haven't realized it yet. If you have time to waste, just pick a major event on Strava, say a marathon, find an athlete who recorded the activity with a FR745, and there you go - you'll find a straight vertical line somewhere in the elevation plot.

  • 0 over 1 year ago in reply to JS

    Second run in now with the new 745. Around 9km in 45min and the issue still did not reappear. I will do a long run on Sunday - I am already curious.