Take the principle of GPS positioning as an example: 24 satellites are evenly distributed on six orbital planes, and each orbital plane has four satellites orbiting the earth, so that ground users can have at least four GPS satellites in our sky for users to use anytime and anywhere.
Each satellite transmits radio signals covering its own orbit plane coordinates and running time to the ground, and the receiving unit on the ground can accurately measure positioning, navigation, landmarks and so on according to these data.
The GPS positioning system uses the basic triangulation principle of satellites, and the GPS receiver measures the distance by measuring the transmission time of radio signals. From the position of each satellite, the distance between each satellite and the receiver can be measured, and the three-dimensional coordinate values of the receiver can be calculated.
As long as the user receives three satellite signals by using the receiving equipment, the user's position can be determined. In general, GPS uses receiving equipment to receive more than four satellite signals to determine the user's position and altitude.
After the end of the ice age 5000 years ago, the original lowlands and valleys became swamps, so people at that time needed to rebuild their villages in the highlands and recuperate. Because of the harsh living environment at that time, the ancestors had to constantly explore new settlements to increase the population.
This triangular navigation system served the commercial exchanges between settlements at that time, and some workers who helped build new settlements could also use it to find their way home. This sophisticated system appeared more than 2000 years before the ancient Greeks invented geometry. It is still one of the largest civil projects in the world.