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Auto Calibrate Elevation to Location? Baro Altimeter?

gaijin
over 8 years ago
Here's another one:

On my Edge 800 it is possible to have the Elevation Auto Calibrate to my starting location. I saved the location, and every time I start a ride from that location I get the pop-up that says the Elevation has Auto Calibrated to that location.

I can not find the same feature on my Edge 820. As a workaround, before starting a ride I go to Navigation>Adjust Elevation and set the elevation immediately before a ride. It is a bit cumbersome, and doeasn't seem to do as good a job as the 800 in managing Elevation over the course of the ride.

The 800 has a barometric Altimeter which means it does not take all the Elevation data from GPS. This has proven very reliable.

The specs for the 820 say it also has a barometric Altimeter, but the recorded Elevation data look like all the data points come from GPS.

Does the 820 indeed have a barometric Altimeter?

TIA for any help.
  • Former Member
    0 Former Member over 8 years ago
    2016.10.14
    EGDE 820 ver.4.10

    Auto Calibrate Elevation to Location - OK !!
    Elevation to Location GPS - NOT OK -50m for me :mad: fix it Garmin please !!
    Manual height setting is well, not falling -50m
    I set manually 100m more, GPS enabled
    GPS does not set the correct height !!!
  • Former Member
    0 Former Member over 8 years ago
    If the device is turned on and the barometric sensor gives one elevation (which due to barometric changes could be significantly different to the last time it was used) and the GPS calculates a different elevation how is the device to know which elevation is correct (unless it has some kind of worldwide elevation basemap).
    It's always going to take some time for the two sensors to come to an agreement.
    If it's that much of a worry you can always take the trouble to find the elevation of your start point and enter it manually at the start of a ride, something I've done in the past with my 810.
  • 0 over 8 years ago
    If the device is turned on and the barometric sensor gives one elevation ... and the GPS calculates a different elevation how is the device to know which elevation is correct ...


    It should be able to calculate the GPS elevation uncertainty. It can't do that with the baro sensor. If the baro disagrees by more than the GPS uncertainty, I'd go with the GPS number. Using both GPS and GLONASS, the uncertainty in satellite calculated elevation should get pretty small pretty fast. I'm guessing that the 820 baro sensors are nowhere near as stable as old tech mechanical altimeters used in aircraft.
  • Former Member
    0 Former Member over 8 years ago
    It should be able to calculate the GPS elevation uncertainty.


    It should, but all my Garmin barometric sensor equipped devices have struggled with this, going right back the my 15 year old eTrex Vista.
  • 0 over 8 years ago
    Not solved. A hardware problem?

    I updated to 4.10. The problem continues: my home is at 100 m. and the device goes down quickly to 44m. After calibrating to 100m the devices goes back down to 44m very quickly. I wonder whether ithere is a hardware problem in the altimeter.
    However if the calibration is done at the start of a workout the altitude works more or less correctly during the ride. It seems that Garmin corrected the software but the altimeter hardware is wrong.
  • 0 over 8 years ago
    It should be able to calculate the GPS elevation uncertainty. It can't do that with the baro sensor. If the baro disagrees by more than the GPS uncertainty, I'd go with the GPS number. Using both GPS and GLONASS, the uncertainty in satellite calculated elevation should get pretty small pretty fast. I'm guessing that the 820 baro sensors are nowhere near as stable as old tech mechanical altimeters used in aircraft.
    If the problem were with baro sensor, the elevation wouldn't be consistently low by the same amount. Changing ambient pressure and an unstable baro sensor would result in the elevation being all over the place rather than being consistently off by the same amount. I think the problem must be in the data base for where mean sea level is in space. As I mention in my previous post, starting with the 520 (I believe it was first) displayed elevation and recorded elevation are not always the same. The displayed elevation is more closely linked to GPS elevation.
  • 0 over 8 years ago
    The posting below is a little old now, but it does help explain why the GPS elevation accuracy is not as good as the horizontal positional accuracy. Without accurate DEM maps for the area you in to use to supplement the level of vertical GPS accuracy we are getting we may be at the limitation of what is possible with low cost commercial grade GPS technology for determining elevation. The Edge models do not support the use WAAS/EGNOS.

    http://gpsinformation.net/main/altitude.htm
  • 0 over 8 years ago
    The posting below is a little old now, but it does help explain why the GPS elevation accuracy is not as good as the horizontal positional accuracy. Without accurate DEM maps for the area you in to use to supplement the level of vertical GPS accuracy we are getting we may be at the limitation of what is possible with low cost commercial grade GPS technology for determining elevation. The Edge models do not support the use WAAS/EGNOS.

    http://gpsinformation.net/main/altitude.htm



    Sounds ok, but doesn't explain why my 820 is measuring about 50-60 meter under sea level and my (broken) 1000 was measuring quitte well (minus 5-10 under sea level) wich is accurate for were I'm living in the Netherlands
  • 0 over 8 years ago
    2016.10.14
    EGDE 820 ver.4.10

    Auto Calibrate Elevation to Location - OK !!
    Elevation to Location GPS - NOT OK -50m for me :mad: fix it Garmin please !!
    Manual height setting is well, not falling -50m
    I set manually 100m more, GPS enabled
    GPS does not set the correct height !!!


    How can I Auto Calibrate the elevation? I can only manually.
  • 0 over 8 years ago
    You need to create a saved location and set the elevation for that point. If you start the timer within a given radius of that saved location it will use the elevation data for that location to set the barometer.