What are the three parts of gps positioning system?

Hello, the GPS global positioning system consists of three parts: the space part-GPS constellation; Ground control part-ground monitoring system; User equipment part -GPS signal receiver. \r\n\r\n 1. Space part \ r \ n \ r \ The space part of NGPS consists of 24 working satellites, which are located 20-200km above the ground and evenly distributed on 6 orbital planes (4 in each orbital plane). \ r \ Orbit inclination is 55 degrees. In addition, there are four active backup satellites in orbit. The distribution of satellites makes it possible to observe more than four satellites anywhere in the world at any time, and can maintain the measurement images with good positioning accuracy. This provides a global navigation capability that is continuous in time. GPS satellites generate two sets of codes, one of which is called C/A code (heading/acquisition \ r \ ncode11023mhz); One group is called P code (PROCISE code 10 123 MHz). P \ r \ n code is controlled by the U.S. military because of its high frequency, low interference and high positioning accuracy, and it is difficult for ordinary people to decipher because of its password. It mainly serves the U.S. military. C/\ r \ nCode is mainly used by people after reducing its accuracy through manual processing. \r\n\r\n2. Ground control part \ r \ n \ r \ The ground control part consists of a main control station, five global monitoring stations and three ground control stations. The monitoring station is equipped with an accurate cesium atomic clock and receiver, which can continuously measure all visible satellites. Satellite observation data obtained by the monitoring station, including ionospheric and meteorological data, are transmitted to the main control station after preliminary processing. The main control station collects tracking data from monitoring stations, calculates satellite orbit and clock parameters, and then sends the results to three \r\n ground control stations. The ground control station injects these navigation data and the commands of the main control station into each satellite running overhead. The form of this injection is that every GPS satellite is injected once a day, and the last injection is made before the satellite leaves the range of the injection station. If a ground station fails, the navigation information pre-stored by the satellite can still be used for a period of time, but the navigation accuracy will gradually decline. \r\n\r\n3. The user equipment part \ r \ n \ r \ is a GPS signal receiver. Its main function is to capture the satellites to be tested selected according to a certain satellite cutoff angle and track the operation of these satellites. When the receiver captures the tracked satellite signal, it can measure the pseudo-range from the receiving antenna to the satellite and the change rate of the range, and demodulate the satellite orbit parameters and other data. According to these data, the microprocessor in the receiver can calculate the position according to the position calculation method, and calculate the latitude, longitude, altitude, speed, time and other information of the user's geographical position. Receiver hardware, built-in software and GPS data post-processing software package constitute a complete GPS user equipment. The structure of GPS receiver is divided into two parts: antenna unit and receiving unit. The receiver generally adopts two kinds of DC power supplies: internal and external. The purpose of setting internal power supply is not to interrupt continuous observation when replacing external power supply. When using off-board power supply, the battery will automatically charge. After shutdown, the battery in the machine supplies power to the RAM memory to prevent data loss. At present, various types of receivers are getting smaller and lighter, which is convenient for field observation.