Terrible experience with elevation readings. Have calibrated to known elevation (using both GPS and manual entry of elevation), then tried both auto calibration on AND off. For a short time, readings are consistent but that doesn't last long. Same location elevation readings change +/- 60 feet or about 25%. Much better accuracy and consistency with non-ABC watches (eg 230). I don't want to have to calibrate before every run I do but that likely solves the problem. GPS elevation worked so much better for me on the 230, 220, 310xt, etc. Hopefully, this is a future firmware change. At the moment though, elevation and elevation gain are only accurate once I download watch data into Sporttracks (and elevation is auto adjusted).
Where are you doing the calibration? The barometer works off pressure changes and if you did the calibration indoors and then go out then that could throw things off especially if there is a large temperature change.
I haven't done any calibrations but did setup a screen with Elevation and GPS Elevation to see what happens. My elevation profiles seem pretty good.
Try that and go outside for a bit and observe that happens before you start the timer.
The barometer works off pressure changes and if you did the calibration indoors and then go out then that could throw things off especially if there is a large temperature change.
You're right about that. Tried it. Same of course after a run (if auto calibration chosen) when returning indoors, even with good GPS coverage. There will be a significant difference between Elevation and GPS Elevation.
I noticed however with outside calibration, upon the GPS lock prior to the start of a run, that the GPS elevation and the Elevation will have the same value. I assume therefore that the 935 auto calibrates to GPS upon the GPS lock prior to the start of a GPS activity like an outdoor run.
It seems to me therefore that if you want to use GPS in calculating elevation, one should always use autocalibration. The watch will automatically use GPS, upon the GPS lock prior to start of the activity, when determining initial elevation.
In contrast, if one chooses to use a known initial elevation, then they should manually calibrate to the known point elevation and then turn autocalibration OFF.
