> I have tried the proposed solutions to resolve the altitude error, without
> I have tried, one at a time, with : installing the night build release,
> installing last year release, reinstalling google play services.
> I am still getting very large cumulative elevation errors, i. e. 350 mt iso
> 50 mt, or 1200 mt iso 350 mt.
> Do you have other suggested solutions to resolve this issue ?
There are a lot of variables: Android API vs proprietary Google Play
API, and various phones may have bugs. Plus, elevation in the Android
API is defined as height above ellipsoid (HAE), which is not what people
think of as elevation -- they generally want to see orthometric height
(very roughly, above some sort of mean sea level).
I recommend running GPSTest, which will show HAE and orthometric height
using the Android API. It shows HAE, mislabeled Alt, and "WGS84
orthometric height", labeled not really wrong as "Alt (MSL)".
Depending on where you are these will be different. But certianly not
by 800m, and even 300m seems beyond the actual range. Around me,
northeast US, orthometric heights values are 29m higher than HAE.
(There is also MyLocation, useful for understanding network location
providers, but it does not show elevation.)
GPSTest is available on F-Droid. I am unfamiliar with the Google Play