Anti-theft protection system for a motor vehicle, and a method for operating an anti-theft protection system

摘要

Anti-theft protection system for a motor vehicle, and a method for operating an anti-theft protection system. The anti-theft protection system has a transmitting and receiving unit in the motor vehicle, which transmits radar signals modulated over a broad bandwidth and then waits for echo signals. A code transmitter, which receives a radar signal, for its part sends back an additionally modulated and coded signal. An evaluation unit analyses all the received echo signals firstly for authorization of the code transmitter and secondly in order to determine the distance between the code transmitter and the transmitting and receiving unit.