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.