Relativistic corrections

The engineers who designed the GPS system took these relativistic effects into account when they designed and deployed the system. One thing they did was to slow down the ticking frequency of the atomic clocks before they were launched so that once they were in their proper orbit stations their clocks would appear to tick at the correct rate as compared to the reference atomic clocks at the GPS ground stations. Further, each GPS receiver has built into it a microcomputer that (among other things) performs the necessary relativistic calculations when determining the user's location.