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Difference in altitude

frank-sport
20 days ago

My watch shows a too high altitude difference for gpx tracked tours. Example: Cycling tour with someone with Fenix. We both had identical distance values, but the difference in altitude was 500 meters for me and 350 meters for him. How can that be? I already tried the options: multi Satellite, best precision, but Same behaviour. Any idea?

  • 0 20 days ago

    was it rainy or extra humid day? maybe his Fenix's barometer hole was moisy a bit

  • 0 20 days ago

    Altitude uses barometric pressure not GPS.  Although in theory its a lot more accurate the Garmin implementation is not.

    If its a long ride the weather can change and cause errors,.  If its not that long things like wind can cause it.  I also suspect the sensor is not temperature compensated.

    Its got worse with recent updates.  If i do a 90 min run around a flat rugby field, its quite often to see 90m elevation gain reported on the watch.  The real figure is likely less than 9.

    A year ago it was quite a bit better but not perfect.

    You CAN try cleaning the sensor as outlined in the manual (ie soapy warm water).

  • 0 20 days ago in reply to RDW

    Example. Mine is 458m, his shows 253m. Is this really from barometer and not gpx?

    It Happens with my forerunner in a hiking group or biking group, in every weather, that i always have much bigger values than the others. 

  • 0 20 days ago

    Yes, the FR255 should be figuring ascent/descent from the barometric altimeter. Do you also get excess "floors climbed" figures in the regular health activity monitoring?

    It uses the GPS to calibrate the altimeter, but should be using the air pressure changes to figure the small, incremental ascent data.

    Try comparing the elevation profile charts from your activity and your friend's recording too.

  • 0 19 days ago

    It also happened to me with the 955 and I solved it with 2 maneuvers, the first was to immerse the watch in water at 40 degrees Celsius and dish soap for about ten minutes, I then shook it and rinsed it, the altitude improved a lot but the graph during the activities was jagged and therefore measured higher values ​​of ascent, I turned it off by holding down the light button and finally everything was back to normal