The fight against car thieves takes many forms. Since there is no collateral in 100% sure, completely preventing theft of the vehicle, one should approach the issue from a different angle. So what, that amateurs of someone else's property will be able to hijack a car, since finding it may turn out to be quick and easy?
The solution to the problem is provided by the vehicle location and tracking system, using American satellites, orbiting the Earth in six circular orbits above 20 thousand. km (GPS) and the terrestrial digital cellular telephone network (GSM) operating at a frequency 900 MHz. The signals sent by satellites and received by the receiver placed in the car allow to determine its location with an accuracy of 50 do 75 m, and even up to 5 m. The position of the car is updated every 1 second using the on-board computer and transmitted via the radio modem to the operations center.
For the system to run smoothly, Location signals must be simultaneously emitted from at least four satellites. The then analyzed difference in the time of their arrival to the receiver is a measure of the current geographical location (co-ordinates: length and width) the car and its speed of movement (with order accuracy 1 m/s). For this purpose, precise digital maps of the area in question are necessary. The principle of operation of the satellite ranger is as follows. The GPS receiver by analyzing the signals from the satellites, determines the exact location of the car and stores the current geographic data in its memory. It is connected to the GSM communication system (properly prepared and adapted mobile phone). The control of the car's position by the control panel consists in starting a GSM connection and receiving data about the vehicle's location from the GPS receiver. The data is displayed on a digital map stored in the computer memory in the central office.
The transmission of the signal from the car is the same. The system may run periodically – position control is performed randomly by the central office (np. according to the schedule agreed with the client) or by the driver. It can take place every given number of hours or minutes, or it can be given continuously. The operations center is operational 24 hours a day. In the event of the theft of the vehicle, it transfers the order to intervene or to security companies, or directly to the police units, then tracks its course. The system is activated after an alarm signal is sent, on the initiative of the attacked driver (np. by pressing an invisible button), or automatically, as a result of intrusion detection or being towed away by sensors, registering the opening of doors or covers, glass breakage, movement in the cabin, changing the position of the car, etc.. Remotely, the engine of the stolen car is immobilized and / or the lights or the horn are turned on.