Throughout the 1960s the U.S. Navy and Air Force worked on a number of systems that would provide navigation capability for a variety of applications. Many of these systems were incompatible with one another. In 1973 the Department of Defense directed the services to unify their systems. The basis for the new system would be atomic clocks carried on satellites, a concept successfully tested in an earlier Navy program called TIMATION. The Air Force would operate the new system, which it called the Navstar Global Positioning System. It has since come to be known simply as GPS.
The new system called for three components: ground stations that controlled the system, a "constellation" of satellites in Earth orbit, and receivers carried by users. The system was designed so that receivers did not require atomic clocks, and so could be made small and inexpensively.
The Soviet Union also developed a satellite-based navigation system, called GLONASS, which is in operation today.
The new system called for three components: ground stations that controlled the system, a "constellation" of satellites in Earth orbit, and receivers carried by users. The system was designed so that receivers did not require atomic clocks, and so could be made small and inexpensively.
The Soviet Union also developed a satellite-based navigation system, called GLONASS, which is in operation today.
GPS Satellite
GPS satellite launches began in 1978, and a second-generation set of satellites ("Block II") was launched beginning in 1989. Today's GPS constellation consists of at least 24 Block II satellites. The system became fully operational in 1995.
GPS Goes Public
GPS was designed so that civilian users would not be able to obtain the same accuracy that the military could. Nevertheless, civilian as well as military applications were intended from the start.
After the downing of Korean Flight 007 in 1983 -a tragedy that might have been prevented if its crew had access to better navigational tools- President Ronald Reagan issued a directive that guaranteed that GPS signals would be available at no charge to the world. That directive helped open up a commercial market.
Deployment of GPS continued at a steady pace through the 1990s, with growing numbers of civilian and military users. GPS burst into public awareness during the Persian Gulf War in 1991. GPS was used extensively during that conflict, so much so that not enough military-equipped GPS receivers were available. To satisfy demand, the Department of Defense acquired civilian GPS units and temporarily changed GPS transmissions to give civilian receivers access to higher-accuracy military signals.
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GPS satellite launches began in 1978, and a second-generation set of satellites ("Block II") was launched beginning in 1989. Today's GPS constellation consists of at least 24 Block II satellites. The system became fully operational in 1995.
GPS Goes Public
GPS was designed so that civilian users would not be able to obtain the same accuracy that the military could. Nevertheless, civilian as well as military applications were intended from the start.
After the downing of Korean Flight 007 in 1983 -a tragedy that might have been prevented if its crew had access to better navigational tools- President Ronald Reagan issued a directive that guaranteed that GPS signals would be available at no charge to the world. That directive helped open up a commercial market.
Deployment of GPS continued at a steady pace through the 1990s, with growing numbers of civilian and military users. GPS burst into public awareness during the Persian Gulf War in 1991. GPS was used extensively during that conflict, so much so that not enough military-equipped GPS receivers were available. To satisfy demand, the Department of Defense acquired civilian GPS units and temporarily changed GPS transmissions to give civilian receivers access to higher-accuracy military signals.
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