How does it work? | Satellite navigation system
the Idea of creating a satellite navigation system was born in the 50-ies of the last century. American scientists led by Richard Kershner watched the signal coming from the Soviet satellite, and found that due to the Doppler effect the frequency of the received signal increases with the approach of the satellite and decreases with its distance. Thus, just knowing your coordinates on Earth, you can measure the position and velocity of the satellite, and Vice versa, knowing the position of the satellite, it is possible to define own speed and coordinates.