In a method for operating an anti-theft system and an anti-theft system operating according to the method, a stationary transceiver sends a question code signal to a portable transponder, which in turn responds with an answer code signal. The answer code signal is scanned at predetermined scanning times...http://www.google.com/patents/US5926107?utm_source=gb-gplus-sharePatent US5926107 - Method for operating an anti-theft system and anti-theft system operating according to the method
