The Global Positioning System (GPS) is a Satellite Navigation System consisting of a collection of 24 satellites; developed, owned, operated, and maintained by the U.S. Government Department of Defense; which orbits 10,900 Nautical Miles or 12,535 Miles above the earth. These satellites complete two orbits in 24 hours. These satellites transmit precise time and their position is space signals back to earth 24 hours a day. GPS Receivers on the earth surface, collect these signals from the satellites. The Receiver on earth can calculate its location and position on earth,with a high degree of accuracy, by calculating its distance and position from three to four of the satellites. The Receivers do this by determining the time it takes the signal to travel from the satellite's known position to the receiver.