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Global Positioning System: Difference between revisions
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== History == | == History == | ||
The design of GPS is based partly on the similar ground-based radio navigation systems, such as [[LORAN]] and the [[Decca Navigator System|Decca Navigator]] developed in the early 1940s, and used during | The design of GPS is based partly on the similar ground-based radio navigation systems, such as [[LORAN]] and the [[Decca Navigator System|Decca Navigator]] developed in the early 1940s, and used during World War II. Additional inspiration for the GPS system came when the [[Soviet Union]] launched the first [[Sputnik program|Sputnik]] in 1957. A team of U.S. scientists led by Dr. Richard B. Kershner were monitoring Sputnik's radio transmissions. They discovered that, because of the [[Doppler effect]], the frequency of the signal being transmitted by Sputnik was higher as the satellite approached, and lower as it continued away from them. They realized that since they knew their exact location on the globe, they could pinpoint where the satellite was along its orbit by measuring the Doppler distortion. <!-- The converse is also true: if the satellite's position were known, they could identify their own position on Earth. (commented because I am not sure of this. At most, they would know the rate at which the distance between themselves and the satellite was changing. There would be at least two points (one each north and south of the equator) for which that would be true, and practically one would not get an exact position, especially with 1950s electronics, even if one knew the satellite's exact orbit, and the exact time --> | ||
The first satellite navigation system, [[Transit (satellite)|Transit]], used by the [[United States Navy]], was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the [[Timation]] satellite which proved the ability to place accurate clocks in space, a technology the GPS system relies upon. In the 1970s, the ground-based [[Omega Navigation System]], based on signal phase comparison, became the first world-wide radio navigation system. | The first satellite navigation system, [[Transit (satellite)|Transit]], used by the [[United States Navy]], was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the [[Timation]] satellite which proved the ability to place accurate clocks in space, a technology the GPS system relies upon. In the 1970s, the ground-based [[Omega Navigation System]], based on signal phase comparison, became the first world-wide radio navigation system. | ||
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Two GPS developers have received the [[United States National Academy of Engineering|National Academy of Engineering]] [[Charles Stark Draper]] prize year 2003: | Two GPS developers have received the [[United States National Academy of Engineering|National Academy of Engineering]] [[Charles Stark Draper]] prize year 2003: | ||
*[[Ivan Getting]], emeritus president of [[The Aerospace Corporation]] and [[engineer]] at the [[Massachusetts Institute of Technology]], established the basis for GPS, improving on the | *[[Ivan Getting]], emeritus president of [[The Aerospace Corporation]] and [[engineer]] at the [[Massachusetts Institute of Technology]], established the basis for GPS, improving on the World War II land-based radio system called [[LORAN]] ('''Lo'''ng-range '''R'''adio '''A'''id to '''N'''avigation). | ||
*[[Bradford Parkinson]], professor of [[aeronautics]] and [[astronautics]] at [[Stanford University]], conceived the present satellite-based system in the early 1960s and developed it in conjunction with the U.S. Air Force. | *[[Bradford Parkinson]], professor of [[aeronautics]] and [[astronautics]] at [[Stanford University]], conceived the present satellite-based system in the early 1960s and developed it in conjunction with the U.S. Air Force. | ||
