How does a navigation system work

This is how a navigation system works

27 satellites permanently on the air

The cornerstones of every navigation system are the digital road map, route planning and route guidance software and position determination using GPS. This global positioning system of the American military consists of 27 satellites orbiting the earth in fixed orbits. Every satellite constantly sends signals to earth: on the one hand its exact position, on the other hand the exact time. To achieve the greatest possible accuracy, every satellite has an atomic clock.

Four satellites for one trip

The GPS chip in a navigation system receives this data. The signal from the satellite requires a certain transit time, depending on the distance between the transmitter and receiver. The further away the navigation system is from the satellite, the later it will receive the transmitted data. If the navigation system knew the exact time to within a fraction of a second, it could calculate the distance directly from the difference to the time received from the satellite. Using the data from three satellites, it would then be possible to geometrically determine one's own position. Since you do not drive an atomic clock for a walk in your car, a navigation system can only determine its own position when it receives at least four satellites. The location can be calculated from the transmitted satellite positions and the differences between the times received. The change in position over time and the Doppler effect can then also be used to determine the speed and direction of travel.

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