The origin of GPS can be traced back to the space race in the late 1950s. At that time, the Soviet Union launched the first artificial satellite “Sputnik”. The Doppler effect of its radio signals inspired scientists, making them start to study the technology of using satellite signals to determine the position of ground receivers. This technology was initially mainly used for navigation of missile submarines in the U.S. Navy.
In 1973, the U.S. Department of Defense launched the GPS project, aiming to provide accurate time and location information globally. Starting from the launch of the first satellite in 1978, by 1994, the constellation configuration consisting of 24 satellites was completed, and GPS successfully achieved global coverage. Subsequently, the GPS modernization plan launched in 1996 focused on improving the performance of satellites and ground systems, especially optimizing accuracy, signal availability, and reliability, and adding multiple civilian signals, which significantly improved the application performance of GPS in the civilian field. In 2000, the U.S. government canceled the “Selective Availability” policy that restricted the accuracy of civilian GPS, which greatly improved the accuracy of civilian GPS and promoted the widespread popularity of GPS in the civilian market.
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