SkyDemon Forums

Garmin Glo as external GPS on Android

http://forums.skydemon.aero/Topic23947.aspx

By FrancisHenninger - 7/16/2017 9:52:15 AM

I noticed a discrepancy between SkyDemon and my Garmin Glo of about 140ft; SkyDemon reports about 140ft less than it should be doing.

‌I have it setup for my tablet (Samsung Tab S2): Garmin Glo (bluetooth) -> Bluetooth GPS (acting as a Mock GPS provider) -> SkyDemon.
The reported altitude by Bluetooth GPS is correct (at least it corresponds with my altimeter and known altitudes/heights). The altitude reported is offset by about -140ft. See attached screenshots (from my phone, same problem).

D‌o you have any idea what the cause could be and if it could be corrected?‌
By FrancisHenninger - 7/30/2017 8:55:16 PM

ZMN - 7/27/2017 8:18:06 AM
FrancisHenninger - 7/19/2017 10:21:03 AM
Tim Dawson - 7/17/2017 11:57:27 AM
Your device is reporting the wrong sort of altitude. Providers of GPS data on Android should be providing altitude relative to the ellipsoid, which software such as SkyDemon corrects so it's relative to the geoid, i.e. above mean sea level. If your GPS or mock locations provider is already performing this correction, the data will end up being corrected twice, resulting in a discrepancy just like what you're seeing.

Since SkyDemon is correct i‌‌n expecting uncorrected altitude data, you'll need to find an option in your Bluetooth GPS provider software or mock location provider software which stops its own correction.

Thanks, I'll take a look into it and see if I can contact the author of the mock location provider.


Please try with the Bluetoth GPS Provider App. You have the option Geoid Correction there. I  use the same set you have with the good result.
Regards‌.

Thanks, that seemed to do the trick. Tried that combination today and the altitude was reported as I would have expected.