Altimeter difference

[ksyrah]

I happen to have my 23 and 20 Telly's in the same location. I like to have the compass app on the screen. I got in the 23 and it stated that the elevation was 91ft. Later that day, I got in the 20 and it said 68ft. The 20 has been driven across multiple states and the altimeter has been really close to the posted elevation signs over passes. When I just drove the 23 to AZ, it was not as close. I know it's just an annoyance but, has anyone come across a way to reset the calibration? Is there actually an altimeter or is it calculated by GPS (which could make sense because it told me I was going the wrong way in a round-a-bout when I wasn't)?

 

[MNBackpacker]

Given there is no method to calibrate for changing atmospheric/barometric pressure, one can reasonably presume elevation is based on GPS.
Now, that could either be by using known map elevations and matching coordinates to that location, or, more likely, using GPS calculated elevations. In that case, at least 4 satellites need to be in view, with the more you have the more accurate you tend to be.
At any given time the number of satellites above you can change, so accuracy of elevation (and position, technically) can shift. I don't think there is any method of calibration; it just kinda is what it is...

 

[OldPilot]

Given there is no method to calibrate for changing atmospheric/barometric pressure, one can reasonably presume elevation is based on GPS.
Now, that could either be by using known map elevations and matching coordinates to that location, or, more likely, using GPS calculated elevations. In that case, at least 4 satellites need to be in view, with the more you have the more accurate you tend to be.
At any given time the number of satellites above you can change, so accuracy of elevation (and position, technically) can shift. I don't think there is any method of calibration; it just kinda is what it is...

Exactly. Before every flight in a light airplane have to set the altimeter to the current value, obtained from the tower or the broadcast ATIS information. Any barometric altimeter needs this. Re straight GPS altitude, it is not super accurate; not good enough for example to guide an airplane guide slope on an instrument approach. That takes a thing called WAAS and Kia is unlikely to add this option to its cars as the roadway pretty much establishes the correct glide slope.

Re "accurate" what is accurate? The sign on the highway that might tell the altitude of a nearby peak or the altitude measured a hundred yards up or down a hilly road? GPS or (maybe) space-based measurement? The guy installing the sign has no idea where the altitude number came from relative to where he's digging the hole for the sign post. And any measurement comes with an error tolerance, whether stated or not.

So, @ksyrah, WADR I think you are doing pretty well with what you have.