Shiva2012 wasn&#x27;t exactly correct, there is no &quot;clock-sync&quot; from ground stations, each satellite has a specifically fined tune atomic clock that is designed to adjust the drift and each adjustment is unique for each satellite based on it&#x27;s position in the constellation.<p>Some additional GR related shifts are corrected in the receivers however GR isn&#x27;t the only thing that can affect the accuracy of GPS and since it&#x27;s constant (although cumulative) it could be potentially corrected by other means if GR was not known at the time.<p>And there are of course other issues that cause errors in GPS many of them were discovered post launch and the system was fine tuned to correct for them mainly on the receiver side.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Error_analysis_for_the_Global_Positioning_System" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Error_analysis_for_the_Global_...</a>