GPS, abbreviated from “Global Positioning System”, is a system used in global position locating. It was an achievement of a giant aerospace project sponsored by the US government through more than 20 years at a cost of 12 billion USD. It supplies round-the-clock information for surface targets in a global range and can fix the variables such as the accurate position, speed and moving direction of the targets.
In 1980’s, the US government lessens the restriction on the use of synchronous satellites, which ushers a new age of satellite application. Consequentially, the use of business satellites greatly enhances the veracity and coverage ratio of communication satellites.
The GPS navigation system is the most effective application of GPS in car industry.
Function Rationale
Car GPS navigation system is composed by two parts. One consists of a GPS receiver and display facility, which is set up in cars. And the other is a computer control center. The two parts contact each other via the satellite positioning system.
The computer control center is authorized by the automobile administration department, mainly in charge of monitoring the dynamic movement and traffic situation of mobile vehicles in its administrative area. Car navigation system has two basic functions. One is car tracking, which means the car will be located in the electronic map by the computer control center wherever it goes as long as a coded GPS receiver device is set in the car. And the other function is driver guiding. Drivers can save the electronic traffic network in a floppy disk and plug it into the car receiver device, and then the position and the current traffic situation will be soon manipulated in the screen. Drivers can not only input the destination and prescribe the best route, but receive instructions from the computer center to choose its route and directions.
Four Factors
The satellite guiding system which guides drivers is composed by four important factors: the satellite signal, signal receiver, signal processing and map data base.
Satellite signal: car satellite guiding system manages to locate position of cars in virtue of GPS. GPS needs to have information of the longitude and latitude of the cars and the concrete altitude in many cases.
Since GPS can only function on the base that it is in the direct monitoring region of the synchronous satellites, tunnels, bridges or high buildings may cover the direct monitoring region, which prevents the guiding system working properly. And since the guiding system calculates the position of cars in virtue of trigonometric and geometric principium, cars can be only positioned when they are at the same time in the monitoring region of at least tree synchronous satellite.
Because most synchronous satellites are over the dense cities, the guiding system would not work so effectively or even break off when cars are out of downtown area.
Signal receiver: the function rationale of GPS system is to parse the signals received from the synchronous satellites. During driving, cars are successively positioned by a device similar to gyroscope which is used in airplanes or ships. However, if the signals are disconnected, data from the speeding device is used as its substitute when timing at the same time.
Signal processing: data received by GPS and data from the speeding device is delivered to the car navigation system via signal receiver device, then analyzed and processed by software and overlapped with the already saved map.
Map database: when the coordinate information from GPS is overlapped with the electronic map, drivers then can see their present position and the direction to go. This last step is called diagram formation, without which, navigation system would have no direction to lead.
The electronic map of car navigation system has kinds of resources, the most important of which is the database of streets and blocks provided by the government. The magnitude, accuracy and immediateness of database are of great importance to an effective car navigation system.
Present Status
At present, 4% of cars are equipped with navigation system before leaving factory in Europe, and 60% in Japan. Many Japanese companies such as Honda, Nissan as well as Panasonic, Pioneer, Alpine and so on have already developed car navigation products of its own.
Although the terminal navigation product market is overwhelmingly occupied by terminal-equipped products, which totalized up to 30 to 40 thousands in 2004, original-equipped products are hardly put into mass production by car companies. Thanks to the Olympic Games 2008, there will be about 70 thousand cars equipped with car navigation terminal products before leaving factory in China. That indicates the original product market will become larger than the terminal product market. However, since the present 15 million cars will form the potential market of terminal navigation system, and the car navigation market in China is still in premier stage, the terminal market can be the main stream in 3 to 5 years after 2007.