User's Manual

4
2.2 Global Positioning System (GPS)
The GPS system is a satellite array which enables a receiver located anywhere on
Earth to determine its exact position, usually to within 100m.
The array uses 24 satellites (plus spares) orbiting the Earth in six orbital planes, four
satellites per plane, as shown below. These are arranged so that at least five satellites
are within range of any receiver (which can be anywhere) at all times.
Each satellite transmits information which enables its position and distance from the
receiver to be calculated. By combining these data for multiple satellites, the exact
position of the receiver can be determined.
GPS satellite orbital planes
Operation of GPS receiver
(
size exaggerated for clarity)