What are the destination setting steps of car navigation?

1. First, click Navigation (usually touch screen, you can choose to enter directly).

2. Then, after the navigation system is started, click Search to enter the selection interface or open the input panel.

The next step is to enter the address. One way is through list selection, and provinces, cities and counties are selected step by step. Another method is to directly enter the address to be searched, and then match it to the address you want to choose. (Note: The navigation system is slightly different, but it's all the same routine. )

4. After the final selection, enter the map with two small flag icons (or buttons, usually prompts), and click Select to set it as the destination.

The principle of car navigation:

Twenty-four GPS satellites orbit the earth at a height of 12000 km from the ground, with a period of 12 hours, so that more than four satellites can be observed at any time and at any point on the ground.

Because the position of satellite is accurately known, we can get the distance from satellite to receiver in GPS observation. Using three-dimensional coordinates and the distance formula in three satellites, three equations can be formed to solve the position (x, y, z) of the observation point. Considering the error between satellite clock and receiver clock, there are actually four unknowns, X, Y, Z and clock difference, so it is necessary to introduce a fourth satellite to form four equations to solve, so as to get the latitude, longitude and elevation of the observation point.

In fact, receivers can often lock on more than four satellites. At this time, the receiver can be divided into several groups with four satellites in each group according to the constellation distribution of satellites, and then the group with the smallest error can be selected by algorithm to locate, which improves the accuracy.

Due to the error of satellite orbit and satellite clock, the influence of atmospheric troposphere and ionosphere on signals, and artificial SA protection policy, the positioning accuracy of civil GPS is only 100 meters. In order to improve the positioning accuracy, differential GPS(DGPS) technology is widely used to establish a reference station (differential substation) for GPS observation. By comparing the precise coordinates of the known reference station with the observed values, a correction number is obtained and released to the public. After receiving the correction number, the receiver compares it with its own observation value to eliminate most errors and get a more accurate position. Experiments show that the positioning accuracy can be improved to 5 meters by using differential GPS.