How does the navigation system find the way? For the electronic pathfinder to give the right route recommendations, the GPS (Global Positioning System) is essential. In this system, originally built for military purposes, 27 satellites (three of them in reserve) orbit the Earth on exact trajectories. These satellites continually transmit signals which are measured by GPS receivers.
For exact positioning with an accuracy of about ten metres, the signals from three satellites must be received. The navigation system in conjunction with the road map stored in its memory converts this information into route recommendations. Nowadays, using GPS, the location of stolen cars which are equipped with a special sensor can also be determined.