The origin of GPS positioning system

When GPS is a navigation satellite measurements Ranging Global Positioning System with the abbreviation (GPS Global Positioning System), is a combination of satellite and communications technology development. He is the United States from the 1970s began to develop, which lasted more than 20 years, costing $ 30 billion, in March 1994 completed a comprehensive real-time and with full air and sea navigation, they are evenly distributed in six tracks, each tablet satellite continuous emission certain frequency radio signal. Just hold portable signal receiving device, then no matter the land, sea or air, can receive satellite send specific signals. Receivers in the computer received satellite signals for analysis, we can determine the location of receivers holder. Car GPS positioning system

U.S. GPS was originally developed for the U.S. military's main purpose is to provide real-time, all-weather navigation services and for intelligence gathering, nuclear explosion monitoring and emergency communications and some other military purposes. Early 1991 Gulf War, the U.S. military had used this technology to deploy troops in the desert.

The original GPS program plan is to 24 satellites placed in three tracks. Each track has eight satellites. However, due to budgetary compression, GPS planning department does not reduce the number of satellite launches, to 18 satellites distributed in six track. However, this program like satellite reliability lost protection. 1988 United States for the last time to modify, use of 21 operational satellites and three spare satellites operate in six track. From 1978 to 1984, the U.S. launched another 11 experimental satellite, and developed a variety of purposes receivers, experiments show, GPS positioning accuracy far exceeds the design standards. February 4, 1989 the first lesson to GPS satellite was successfully launched, thus declaring GPS positioning system into construction state.

Practical end of 1993 that the GPS constellation GPS network has been built in the future will be based on plans to replace the failed satellite.