GPS global satellite positioning system is a system that uses navigation satellites for positioning, navigation and time measurement. It consists of three parts: the space part, the ground control part and the user equipment part. Among them, the space part is composed of 24 satellites, which are distributed on 6 orbital planes, and each orbital plane has 4 satellites; the ground control part is composed of the main control station, monitoring station and information injection station; the user equipment part is the GPS receiver .
The principle of GPS is based on the concept of Time Difference of Arrival (TDOA). GPS satellites are equipped with high-precision atomic clocks, which can generate very accurate navigation information. At the same time, each GPS satellite has an ephemeris, which records information such as the position and speed of the satellite. When the GPS receiver receives the signal from the GPS satellite, it will calculate the location of the receiver according to the time difference between the arrival of the signal.
Specifically, when a GPS receiver receives a signal from a GPS satellite, it records the time when the signal arrived. At the same time, GPS satellites will also send their own time information to the receiver. Since the speed of light is known, the receiver can calculate the distance between the receiver and the satellite by comparing the difference between the satellite time and the receiver time.
However, a single satellite cannot determine the position of the receiver because there is only one distance information. Therefore, at least three GPS satellites are required to calculate the latitude and longitude of the receiver. The specific method is: assuming that the receiver is on an unknown point on the earth’s surface, it calculates three distance values through the received signals of three GPS satellites, and then uses these three distance values and the positions of the three satellites to solve the problem. The latitude and longitude of the receiver.
In practical applications, the GPS receiver can also improve the positioning accuracy by receiving the time base signal from the ground control part. The ground control part will regularly send a time base signal to the GPS satellite, and the GPS satellite will send this time base signal to the receiver. The receiver can further correct its own time error by comparing the difference between this time base signal and its own internal clock, thereby improving the positioning accuracy.
In short, the GPS global satellite positioning system is a system that uses navigation satellites for positioning, navigation and time measurement. Its principle is based on the concept of time difference of arrival, by comparing the difference between the satellite time and the receiver time to calculate the position of the receiver. The GPS receiver can also improve the positioning accuracy by receiving the time base signal from the ground control part. The application of GPS technology has brought great convenience to our life and work. It can not only be used in vehicle navigation, aviation navigation and other fields, but also in measurement, monitoring and other fields.