GPS is the second -generation satellite navigation system in the United States. It is developed on the basis of the Ziwuyi satellite navigation system, and it adopts the successful experience of the Wuwuyi system. According to the planning plan, the GPS space part uses 24 satellites with a height of about 20,200 kilometers to form a satellite constellation. The 24 satellites are near -circular orbit. The operating cycle is about 11 hours and 58 minutes. It is distributed on the 6 orbit planes (4 per track surface), and the orbital inclination angle is 55 degrees. The distribution of satellites allows more than 4 satellites to observe more than 4 satellites around the world, and can maintain a good positioning and solving geometric graphics. This provides continuous global navigation capabilities in time .

In the 1970s, Lu, Hai, and Air Force jointly developed a new generation of global positioning systems. The main purpose of GPS was to provide real -time, all -weather and global navigation services for Lu, sea, and air forces. After more than 20 years of research experiments, such as more than 20 years of research experiments, such as more than 20 years, by more than 20 years, by more than 20 years, by 1994, 24 GPS satellite constellations with a global coverage rate of 98%have been completed. GPS has gone through the first and second -generation, and has been upgraded to the third generation to maintain its hegemonic position in the navigation positioning system. GPS is the most accurate and widely covered navigation positioning system in the world .

The initial GPS plan was formulated under the leadership of the United States United Planning Administration, which placed 24 satellites on three rails of 1200. There are 8 satellites on each orbit, and 6-9 satellites can be observed on the earth. In this way, the accuracy of the thick code can reach 100m and the precision accuracy is 10m. Due to the compression of the budget, the GPS plan had to reduce the number of satellite launch, and changed to distributed 18 satellites on 6 orbits of 600. However, this plan could not guarantee the reliability of satellites. The last modification was carried out in 1988: 21 working satellites and 3 spare satellites work on the 6 orbits of each other 600. It is also a way to work used by GPS satellites.

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