The vehicle GPS navigation system consists of two parts: one part consists of GPS receiver and display equipment installed on the vehicle; The other part is composed of computer control center, and the two parts are connected through positioning satellites.

The computer control center is authorized and established by the motor vehicle management department. It is responsible for observing the dynamics and traffic conditions of designated vehicles within its jurisdiction at any time. Therefore, the whole vehicle navigation system has two basic functions: one is the vehicle trace monitoring function. As long as the encoded GPS receiving device is installed on the vehicle, the vehicle can indicate its location on the electronic map of the computer control center wherever it travels.

Brief analysis of working principle of positioning system in automotive electronics

The other is the driving guide function. The owner can store the electronic map of traffic routes in various regions on the floppy disk. As long as the floppy disk is inserted into the vehicle receiving device, the display screen will immediately display the location of the vehicle and the current traffic status. It can not only input the destination to go, prepare the best driving route in advance, but also accept the instructions of the computer control center, Choose the route and direction of the car.

The satellite navigation system for guiding drivers has the following four important factors: satellite signal, signal reception, signal processing and map database. Satellite signal: the vehicle satellite navigation system needs to rely on the global positioning system (GPS) to determine the position of the vehicle. GPS needs to know the longitude and latitude of the car. In some cases, it also needs altitude to accurately locate.

Because GPS needs the vehicle navigation system to work within the direct line of sight of the synchronous satellite, tunnels, bridges or high-rise buildings will block the direct line of sight, making the navigation system unable to work. Moreover, the navigation system uses the laws of triangulation and geometry to calculate the vehicle position, so the vehicle can determine the position only when it is under the sight of three synchronous satellites at least at the same time.

Of course, most synchronous satellites are over densely populated metropolises, so when you are far away from the urban area, the navigation system will not work well or even at all.

Signal reception: the working principle of GPS system is to analyze the signals received from synchronous satellites. A device similar to the gyroscope used in aircraft or ship navigation can continuously provide the position of the car during the driving of the car. However, when the satellite signal is interrupted, the data provided by the speedometer is used to fill the gap and record the driving time.

Signal processing: the signal received by GPS and the information provided by the speedometer shall be provided to the vehicle navigation system through the receiver, analyzed and processed by the software system, and overlapped on the stored map.

Map database: when the coordinate information provided by GPS is superimposed on the electronic map, the driver can see his current position and future direction. This last step is called mapping. Without mapping, the navigation system has no direction. The map database of vehicle navigation system comes from many channels, among which the most important source is the block database provided by urban government organs. For a good vehicle navigation system, the number and accuracy of maps and the timeliness of data are very important.

At present, 40% of European and American cars are equipped with navigation system before leaving the factory, and 60% of Japanese cars are equipped with navigation system before leaving the factory. Japan’s HTC, Nissan, Honda, Panasonic, pioneer, alpai and other companies have developed their own vehicle navigation products.

At present, China’s navigation terminal market is also dominated by rear mounted products. In 2004, there were 30000 or 40000 vehicles in the market, while there were almost no front mounted products, and automobile manufacturers began large-scale mass production. However, due to the impact of the 2008 Olympic Games, about 70000 cars will be equipped with car navigation terminals when leaving the factory in 2006, so the front loading market may be temporarily larger than the rear loading market. However, about 15 million vehicles in China are the potential market of rear mounted navigation terminals, and China’s vehicle navigation market is still in the start-up period, so the rear mounted market will still be the mainstream of the market in the next three to five years after 2007.


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