Niels Bohr Institutet > Kalender - det sker på NBI > 2009 > The American Global Po...

Kollokvium by Jan Valentin

For the American Global Positioning System (GPS), first order relativistic corrections are found to be in the range of up to 50 nanoseconds, which comes to a miscalculation of up to 15 meters.

After a short introduction on how the GPS network determines position on the surface of the Earth, orbital motion and relativistic effects are deduced.

Firstly we deduce the GPS satellite clock rate offset. Secondly the eccentric anomaly time evolution equation is deduced. This equation serves two purposes: 1) Able prediction of a satellite's exact position in a given orbit. 2) Creating the tools needed for deducing some first order relativistic effects. From the latter the variable satellite clock rate aberrations are found.

Thirdly the Sagnac correction to light signals in the rotating frame is found.

Lastly the GPS network and receiver relevant relativistic corrections are presented in a simulation.

No new theory is presented in this lecture.

Supervisor: Mogens Høgh Jensen