1, satellite signal

Car satellite navigation systems rely on the Global Positioning System (GPS) to determine the location of the car. At its most basic, GPS needs to know the longitude and latitude of the car. In some special cases, GPS also needs to know the altitude to accurately locate. With these three sets of data, the accuracy of GPS positioning can often reach 2 to 3 meters.

Because GPS requires a car navigation system to work within the direct line of sight of a geosynchronous satellite, tunnels, bridges, or high-rise buildings block this direct line of sight, making the navigation system inoperable. Moreover, the navigation system uses the triangle and geometric rules to calculate the position of the car, so the car must be at least under the line of sight of the three synchronous satellites to determine the position. The more synchronized satellites in the direct line of sight of the navigation system, the more accurate the positioning. Of course, most of the geosynchronous satellites are in the densely populated metropolis, so when you are away from the city, the navigation system will not be too good or even work at all.

2, signal reception

The GPS system works by parsing the signals received from the geosynchronous satellites. Projected on a vertical plane, these signals can be visually represented as individual inverted funnels. When the lower half of these "funnels" have a certain overlap, the GPS analysis program can calculate the coordinates of the location of the car. In the process of driving a car, a device similar to a gyroscope for aircraft or ship navigation can continuously provide the position of the car. However, when the satellite signal is interrupted, the data provided by the speedometer is used to fill the gap and is used to record the travel time.

3, signal processing

The signals received by the GPS and the information provided by the speed measuring device are provided to the car navigation system through the receiver and analyzed and processed by the software system, superimposed on the stored map.

4, the map database

When the coordinate information provided by the GPS is superimposed on the electronic map, the driver can see his current position and future direction. This last link is called mapping and is the most important part of the car navigation system. After leaving the map, the navigation system is equal to no direction.

The map database of the car navigation system comes from a variety of channels, the most important source of which is the block database provided by the city government agencies. For a good car navigation system, the number of maps, the accuracy, and the timeliness of the data are all important. No matter how accurate the coordinates of the GPS are, if your navigation system can't provide a map of your area, or if the map provided is wrong, your system can be said to be worthless.