by MacM: Ronald R. Hatch:"But these statements are patently untrue of GPS. It may appear to be a subtle difference, but it is very important to note that the GPS satellites' clock rate and the receiver's clock rate are not adjusted as a function of their velocity relative to one another. Instead, they are adjusted as a function of their velocity with respect to the chosen frame of reference—in this case the earth-centered, non- rotating, (quasi) inertial frame." Emphasis added by MacM. Now GR clearly has a many factor affect over velocity at this range but I think it would be hard for you to explain why the velocity calculation I did matches the calibration cited by the manufacturer if it were not true. =============================================================== No Mac, it is not hard for me to explain at all. I have repeatedly linked to the true preset adjustment on the clocks in this and other threads. Have you forgotten, or did you just not understand what was being said? You fail to understand what is stated in the cut & paste above. He did NOT state 7.2 microseconds were being deducted from the tick rate of the satellite clocks. He stated they were adjusted with reference to the chosen Earth-centered, NON-ROTATING, (quasi), inertial reference frame. In that (quasi) frame of reference, their is no relative velocity between the Earth's center and the satellites, thus no adjustment to the tick rate in the clocks. It is a 'artificial' frame of reference in which the satellites do not move in relative to the Earth's center.