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Bad GPS reception pace? Recalculates?

BowMaestro
over 4 years ago

Hi guys and gals :)

Maybe not the best forum, but i guess it calculates somewhere?
When i run in to an area with a little poorer GPS reception, ie trees overhanging in the forest or so.
My Pace on the watch can go way upp, from 5:00 ish /km, to 11:00 min per km for a little while.
Not really ideal.
But when i get out of the poor reception area, will the watch, or connect web, notice that i didn't at all run that slow since i arrived further ahead than interpreted before?

Or is the logged data not smart handled afterwards?

Any suggestions?

  • 0 over 4 years ago

    I double checked my history.

    never during this run I was down to 11min/km.

    but still it was recorded so.

    that must be a really bad calculation of the run then?

  • 0 over 4 years ago

    The data is not recalculated afterwards, but the average overall pace does seem to be calculated on final distance divided by time. I ran a 5k today witch shows up as 5:50/km (which is about right) but for most of the first kilometer the pace doesn't come above 7min/km. However when switching the view in web Connect from time to distance and back you can see that the 1km distance mark is around the 5:50 time mark. The pace however is not adjusted. When looking in Strava on the same run, the pace differs wildly, and seems more correct, possibly because Strava calculates the pace based on 'good' GPS location hits and time, instead of maybe on the guestimated 'step length' adn 'cadence', which I think Garmin might use (not sure on that though).

  • 0 over 4 years ago in reply to Drak

    Awesome analysis, and sounds about right.

    im waiting to hear back from Garmin support as well, let’s see how well they can explain.

    thanks mate!

  • 0 over 4 years ago in reply to BowMaestro

    If you post a link to the activity and make it public, we can have a look at it, and tell you better what happened.

  • 0 over 4 years ago in reply to trux

    Here's the link to my run. It's only the first km-and-a-bit that has really bad pace data, the rest seems more plausible. 

    Edit: Hmm, it seems not to accept my link.

    https://connect.garmin.com/modern/activity/6169552711   - ah there we go

  • 0 over 4 years ago

    The device won't recalculate. When running in areas with poor GNSS reception the recommendation is to use a foot pod sensor. Set the Speed and Distance options to "Always".

  • 0 over 4 years ago in reply to Drak
    Drak said:
    connect.garmin.com/.../

    Well, in your case it simply looks like the GPS was not locked properly yet, when you started. Perhaps due to an expired EPO / CPE file. So the watch needed a couple of minutes before catching up. Verify whether the starting point and time really match the reality.

  • 0 over 4 years ago in reply to trux

    The starting point is exactly right, and the time seems pretty much correct. Also, I walk a bit away from my house to get to the starting location and the GPS indicator generally turns green after about 15 seconds.

  • 0 over 4 years ago in reply to nradov

    Interesting that a 600 euro watch cannot perform calculations like this. And that when uploadeing the data to STRAVA the pace is much more consistent with reality for that first bit.

  • 0 over 4 years ago in reply to Drak
    Drak said:
    Interesting that a 600 euro watch cannot perform calculations like this. And that when uploadeing the data to STRAVA the pace is much more consistent with reality for that first bit.

    Im with you on this.
    I really hope Garmin will have a ok answer on this. And it might not be as bad as some of us think.
    As far as i know the data i get i good enough for my training, but i really want to know how it does the calculations så i know what i see. Ill get back with a few activities, if i found them not to make me too public.