GPS & Relativity: Position Error Lower Than 38000 Feet?

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    Gps Relativity
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The discussion centers on the claim that GPS satellites experience a time difference of approximately 38,000 nanoseconds per day compared to ground clocks due to relativistic effects, potentially leading to a positional error of 38,000 feet per day if uncorrected. However, participants argue that this reasoning is flawed because GPS receivers continuously sync their clocks with satellite signals, preventing significant error accumulation. The consensus is that while relativistic effects exist, they are compensated for, and the actual positional error is much lower than the initial estimate. Calculations presented indicate that the error due to timing discrepancies would be negligible, around 8.9 mm, reinforcing the idea that GPS remains highly accurate. Overall, the thread concludes that the assumption of significant error accumulation in GPS positioning is incorrect.
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Even atomic clocks are not perfect. If they were then I think the OP would have been right. For everything to stay synchronized the clocks on each satellite must re-synchronize from time to time with a master clock. The master clock is ground based so if relativistic effects were not compensated for then a satellite that just had its clock synchronized would be out of sync with a satellite that had been synchronized less recently. having satellites out of sync would certainly cause error, though I don't know how much.

http://tycho.usno.navy.mil/gpsinfo.html

Also, the GPS system is designed to provide 4 co-ordinates, not 3. The 4'th being time. If the master clock were space based and time dilation were not accounted for the time co-ordinate would drift. A cheap receiver with a fallible clock would not know how much drift to account for.
 
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