How the GPS Works
Posted on April 20, 2008
When a network of satellites is placed into orbit, Global Positioning System or GPS can be put to work. As GPS satellites circle the earth in a very precise orbit, it is able to transmit signal information to earth. The GPS receivers pick up this information and calculate the user’s exact location by triangulation. The GPS receiver compares the time of transmission of the signal by a satellite with the time it was received. How far away the satellite is can be determined by the GPS receiver through the time difference. With distance measurements provided by a few more satellites, the user’s position is determined by the receiver and displays it on the unit’s electronic map.
The calculation of a 2D position (latitude and longitude) and track movement can be done when a GPS receiver is locked on to the signal of at least three satellites. The user’s 3D position (latitude, longitude, altitude) on the other hand can be determined with at least four more satellites in view. The GPS can easily calculate other information such as speed, bearing, track and others once the user’s position is determined.
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