| 摘要 |
PURPOSE: To accurately recognize the position of a vehicle by receiving and analyzing a vehicle tracking signal transmitted by a host control center and transmitting a vehicle position signal in response to this signal in the case that this signal is a call to the vehicle itself. CONSTITUTION: This system consists of a host control center CC, many sites S1 to S3, and a device on vehicle. In this case, a peculiar address is given to the device on vehicle, and the address is in a form of a POCSAG code. The host control center CC subjects a signal in a form of a POCSAG code, which includes the address of the vehicle to be tracked, to FSK modulation and transmits it, and the device on vehicle analyzes the transmission signal; and if the address included in the received signal coincides with the address of this device itself, the device transmits a signal in a form of a PRN(Pseudo Random Noise) code after PSK modulation in response to the received signal. Further, response signals are transmitted from site antennas S1 to S3 to the host control CC, and the host control center CC receives them to calculate and recognize the position of the vehicle. Thus, the position of the vehicle is accurately recognized. |
