How Does It Work?
Satellite Navigation devices utilise the United States' Global Positioning System (GPS), which as of 2007 is the only fully functional, fully available global navigation satellite system.
It consists of up to 32 medium Earth orbit satellites in six different orbital planes, with the exact number of satellites varying as older satellites are retired and replaced. Operational since 1978 and globally available since 1994, GPS is currently the world's most utilized satellite navigation system.
The satellites continuously co-ordinate their position with one another and with fixed stations. This enables each satellite to know its exact position in relation to the ground. The Sat Nav device is then continuously updated by these satellites about its exact position on the ground.
