I have a pretty good GPS receiver. Trimble R8 with a Yuma data collector. Normally we use it only for lats and longs. It is corrected in real time with a cellular data modem and a RTK/VRS ground station network.
Yesterday we did a shot from a hill that did not exist when shuttle radar data was taken. It was way off in elevation. So we took a shot from our parking lot and compared it with what we think we know to be the altitude as well as our cell phones and google earth. Turns out the R8 has an ellipsoid height as well as another height associated with the northing and easting values. The second one seems to be more in line with what I was expecting. The local dealer sent me a drawing showing this. (attached) So now I am super confused. Not sure what number to use when working with Radio Mobile. Do I add the geoid height to the ellipsoid height? Was hoping Brian Webster may know or others may know. Googling google earth elevation talks about different versions of geoid. Not sure if their elevations are geoid elevations or not. So, rather than dig into it any more I am taking the lazy approach and posting the question here.
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