Basic Principles of Satellite Navigation

Satellite Navigation Systems all use the same basic principles to determine coordinates:
• Satellites with a known position transmit a regular time signal.
• Based on the measured travel time of the radio waves (electromagnetic signals travel through space at the speed of light c = 300’000km/s) the position of the receiver is calculated.
We can see the principle more clearly using a simple model. Imagine that we are in a car and need to determine our position on a long and straight street. At the end of the street is a radio transmitter sending a time signal pulse every second. Onboard the car we are carrying a clock, which is synchronized to the clock at the transmitter. By measuring the elapsed travel time from the transmitter to the car we can calculate our position on the street .