principle of operation
GPS consists of three parts: space satellite, ground monitoring and user receiving. In space, there are 24 satellites forming a distribution network, which are distributed in six quasi-synchronous orbits with an inclination of 55 degrees and a distance of 20,000 kilometers from the ground, and each orbit has 4 satellites.
GPS satellites orbit the earth once every 12 hour, so that signals from 7 ~ 9 satellites can be received at any place on the earth at the same time. There are 1 master control stations and 5 monitoring stations on the ground, which are responsible for satellite monitoring, telemetry, tracking and control. They are responsible for observing each satellite and providing observation data to the main control station.
After receiving the data, the main control station calculates the precise position of each satellite at each moment, and transmits it to the satellite through three injection stations, and then the satellite transmits these data to the receiving terminal equipment of the user through radio waves.