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Disable barometer to get GPS elevation ?

Bast M
over 4 years ago

Hi,

Is there a way to disable the barometer and get the elevation info from GPS ? I know we can set the altimeter mode to auto / barometer / altimeter. But this setting does not affect the activity elevation based on the barometer. And there are some problems because of that : on a track running activity (so 0 elevation ...), the activity has too much elevation gain (ie 150m).

This is annoying, I have to fix it manually in Garmin Connect and Strava.

  • 0 over 4 years ago

    I understand your problem, but using GPS for elevation would actually make your problem worse rather than better. There is much more noise in GPS-based elevation because of the small angles in the vertical direction. I think your method of correcting the elevation afterwards using their elevation model is probably your best choice.

  • 0 over 4 years ago in reply to Danny

    Hi Danny, you're probably right.

    But how the other watches (which don't have a barometer) do their elevation estimation ? Is it based on the GPS ? For example, my Polar Vantage M does not have a barometer, but show a correct elevation during an activity.

  • 0 over 4 years ago in reply to Bast M

    Its software is probably doing a lot of smoothing of the GPS data to get rid of noise.You might see this being more "accurate" on a level track as the errors kind of get cancelled out, but the downside is that it will be far less accurate in representing actual differences in altitude when not on a level track.

  • 0 over 4 years ago

    No one uses the GPS elevation. For watches without barometer, the elevation profile is generated using a DEM (digital elevation model, see e.g. Shuttle Radar Topography Mission). This is usually called "elevation correction" and works quite well in areas without many trees. In the forest the model often uses treetops as ground level, which lead to several "jumps" in the profile.

    It seems that your altimeter is broken. Perhaps enableing "elevation correction" in your activities will do the trick for you.