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'''Global Positioning System''' ('''GPS''') is a [[United States]] [[satellite]] system that lets those on the ground, on the water or in the air determine their position with extreme accuracy using GPS receivers. These receivers rely on precisely timing signals sent from GPS satellites, with corrections for atmospheric attenuation and relativistic effects.

'''Global Positioning System''' ('''GPS''') is a [[United States]] [[satellite]] system that lets those on the ground, on the water or in the air determine their position with extreme accuracy using GPS receivers. These receivers rely on precisely timing signals sent from GPS satellites, with corrections for atmospheric attenuation and [[relativity|relativistic]] effects.

The system was developed by the US [[Department of Defense]] and made available to the general public in 1983 under orders of [[Ronald Reagan | President Reagan]]. GPS for civilian use used to include a mechanism called Selective Availability that intentionally limited the accuracy of GPS, a mechanism originally intended to confuse potential enemies who might launch a missile attack, but Selective Availability was disabled in 2000, and appears unlikely to be reinstated in the foreseeable future.

The system was developed by the US [[Department of Defense]] and made available to the general public in 1983 under orders of [[Ronald Reagan | President Reagan]]. GPS for civilian use used to include a mechanism called Selective Availability that intentionally limited the accuracy of GPS, a mechanism originally intended to confuse potential enemies who might launch a missile attack, but Selective Availability was disabled in 2000, and appears unlikely to be reinstated in the foreseeable future.