How was the satellite positioning system “GPS” indispensable for map apps and car navigation systems born?


How was the satellite positioning system “GPS” indispensable for map apps and car navigation systems born?

by DragonImages

Various functions using the location information of smartphones and the basis of car navigationGPSIs an indispensable technology for people's lives. A news site specializing in such GPS-related informationGPS WorldExplains how GPS was born.

The Origins of GPS, and the Pioneers Who Launched the System-GPS World: GPS World

GPS is operated by the United StatesSatellite positioning systemHowever, it started with the first artificial satellite launched by the Soviet Union on October 4, 1957.Sputnik 1was. The United States, which was ahead of the Soviet Union in space development, mobilized many researchers and analyzed Sputnik 1. Among them, played a very big role in the birth of GPSInstitute of Applied Physics, Johns Hopkins University(APL)There were also William Guier and George Weiffenbach, physicists.

by NASA-Imagery

Guier and Weiffenbach, who paid attention to the fact that Sputnik 1 sends signals at regular intervals, are caused by the relative speed between this signal and the ground surface.Doppler effectWill find that Sputnik 1's orbit can be accurately identified. Also, APL physicist Frank McClure suggested, "If you use satellite signals you already know orbit, you should know where you are on the planet." The idea of ​​this reversal became the starting point for GPS.

The United States, which was under the Cold War with the Soviet Union, was developing and deploying missile submarines that play a central role in nuclear deterrence. Location information was essential. Therefore, Dick Kershner, APL's space director, led the artificial satellite “transit"Has started development. Although "Transit 1A" launched in September 1959 failed to reach the orbit, the following "Transit 1B" was successful, and full-scale operation began in 1964.

The transit position measurement error is about 25 meters, and if the user is moving, it is necessary to accurately grasp the speed, and if the speed is shifted by 1 knot (1.852 km / h), the measurement result is 0.2 Kiri (370.4 m) could be out of place. In addition, unlike GPS, which can grasp position information three-dimensionally, transit can only identify two-dimensional coordinates.

Unlike submarines that used antennas at sea level 0m above sea level while using transit, troops deployed on undulating ground and aircraft flying in the sky can accurately grasp the current location in a three-dimensional manner that also considers the height. Location information is required. In 1962, I first noticed the importance of location information in 3D, a non-profit organization aimed at developing aerospace technology.The Aerospace CorporationIvan Getting, the CEO of. Mr. Getting, who was a former soldier,US Department of Defense(Pentagon)As a result of furious efforts, the US Air Force has started a new satellite navigation technology development project "Program 621B". This “Program 621B” became the prototype of the later GPS. Getting this achievement, together with Bradford Parkinson, who later played an important role in GPS development,Charles Stark Draper AwardHas won.

James Woodford and Hideyoshi Nakamura, researchers at The Aerospace Corporation, played a central role in Program 621B. Both are secretly submitted to the Pentagon as military secrets in 1966, “Woodford / Nakamura report”, a method called “3Δρ (triple delta low)” that measures three-dimensional coordinates and time with four artificial satellites Was advocated. With this method, the theory of obtaining 3D position information was established, but there were a lot of technical problems to realize. This is because, in order to realize this method, it was necessary to mount an atomic clock on the satellite, but at that time there was no atomic clock that could be used in space.

From left: Mr. Ivan Getting, Mr. Hideyoshi Nakamura, Mr. James Woodford.

While the US Air Force was promoting Program 621B, the US Navy Research Institute (NRL) was developing its own project. That is a researcher at NRLRoger EastonThis is the “Timation project” started under his supervision. In 2010, Easton was credited with having played an important central role in Timation.National Inventor Hall of FameI went in.

A total of 4 artificial satellites were launched in the “Timation project”. "Timation 1", first launched on May 27, 1967, is very stableQuartz watchWas installed,Solar stormI faced the problem of changing the frequency. Also, due to the failure of “Timation 1,” the signal emitted by the satellite isionosphereIt became clear that it would be delayed by the influence of. For this reason, “Timation 2” launched on September 30, 1969, emits two different frequency signals.Crystal oscillatorTo solve the problem of signal delay in the ionosphere, but the effect of the solar storm was inevitable.

NRL is then two lightweightRubidium oscillatorIn July 1974, "Timation NTS-1" equipped withCesium atomic clockWith the launch of “Timation NTS-2” in June 1977, we have accumulated experience in the operation of atomic clocks in space.

While the Air Force-led Program 621B is theoretical and the Navy-driven Timation project is technically successful, the fact that two different projects require significant budgets is a headache for the Pentagon. was. Meanwhile, Parkinson, who was appointed to the top of Program 621B, which was getting stuck, went directly to the Pentagon in September 1973 and said, “Program 621B makes it possible for users to have no atomic clock. "Achievable 3D position information function that can be used" "NRL's" Timation project "has a relatively stable atomic clock on the satellite, replacing the method of relaying signals on the ground that" Program 621B "is promoting And proposed a new project that integrates the two projects. This new project is the GPS development project. Parkinson's proposal was officially approved on December 14, 1973, and the “GPS Joint Program Office (JPO)” was established to integrate Naval Air Force projects. Under the JPO, the best brains from all over the United States will be collected, and we will continue to develop GPS.

Starting with the launch of the first generation GPS satellite “Navstar 1” on February 22, 1978, JPO launched 10 satellites by 1985 to complete the initial GPS. After that, including the retired satellites, a total of 74 satellites have been launched by August 22, 2019, and the GPS constructed by these satellites was predecessor of JPO.Global Positioning System Air WingAs a result, the operation continues even when the article is created.

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