How accurate are height measurements in mobile phones?

Question

How accurate are height measurements from a GPS mobile phone? I realized that the lat / long length can vary by hundreds of meters, but is this the same level of uncertainty that is present in the height values?

In particular, I work with Windows Phone 7, but I'm sure this question applies to other mobile devices. I expect that there are only a few manufacturers of GPS chips, and the same chip will be used by different phones.

This question relates to how it is designed, but it does not say anything about accuracy or reliability.

Answer 1

Since triangulation returns a point in space, the same inaccuracies will apply to the Z axis, as well as to X and Y.

In other words, it is no more and no less accurate than the accuracy of LAT / LONG.

Answer 2

I don’t know specifically about the iPhone, but the altitude is often much less accurate than the X, Y information from GPS. There are some sources of information about this.

Answer 3

This requires sophisticated mathematics to fully understand it, but the absolute altitude at ANY gps is not as accurate as lat / long position.

http://weather.gladstonefamily.net/gps_elevation.html

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

http://www.sawmillcreek.org/showthread.php?83752-Do-civilian-GPS-unts-do-accurate-altitude

quote from the third link: “The altitude error is much higher because it is a satellite system. If you think about it, the best satellite positions for perfect reading will be evenly distributed in the imaginary sphere surrounding you. Unfortunately, since you are standing on the ground, this excludes half spheres, because you need direct line of sight on the satellite.In practice, this even eliminates the constellation with satellites located close to the horizon.So, your corrections will be overhead - this means that the cumulative error in is new in the vertical plane, so I think the preliminary estimate is vertical error = horizontal error 1.5x. "

Answer 4

Vertical error is indicated as horizontal error 1.5 *. You must also allow a local deviation between the geodetic model and the surface of the planet, since the geodesic flattened spheroid model is an approximation only when local correction tables are used.