Smart Self Test
The on-board terminal can conduct self-diagnosis. In the event of a failure, it will send a failure notice to the center to facilitate the maintenance of the staff and ensure the normal operation of the equipment.
The GPS program began in 1973 and was fully operational in 1994. The entire GPS system consists of a space section, a ground control section, and a user section:
Space section (space section)
The space part of GPS is composed of 24 GPS working satellites. These GPS working satellites together constitute a constellation of GPS satellites, of which 21 are satellites that can be used for navigation and 3 are active spare satellites. The 24 satellites are distributed around six orbits with an inclination of 55° orbiting the Earth. The operating period of the satellite is about 12 stars. Each GPS working satellite emits a signal for navigation and positioning. GPS users use these signals to work.
The GPS control part consists of a monitoring system consisting of several tracking stations distributed around the world. According to their different roles, these tracking stations are divided into master control stations, monitoring stations, and injection stations. There is a main control station located at Falcon Air Force Base in Colorado, USA. Its role is to calculate the satellite ephemeris and satellite clock correction parameters based on the observation data of each monitoring station. And so on, and these data are injected into the satellite through the injection station; at the same time, it also controls the satellite and issues instructions to the satellite. When the working satellite fails, the spare satellite is dispatched to replace the failed working satellite; in addition, the main The control station also has the function of a monitoring station. There are five monitoring stations, four of which are located in Hawaii, Ascension, Diego Garcia, and Kwajalein. It is to receive satellite signals and monitor the working status of satellites; there are three injection stations located in Ascension, Diego Garcia, and Kwajalein. The role of the injection station is to The satellite ephemeris and satellite clock corrections calculated by the control station are injected into the satellite.
User section (ground reception)
The user part of GPS is composed of GPS receiver, data processing software and corresponding user equipment such as computer meteorological instrument. Its role is to receive signals from GPS satellites and use these signals for navigation and positioning. The above three parts together form a complete GPS system.