Conti Temic Microelectronic Gmbh

Karlheinz Mueller

Udo Knepper

Rolf Schuler

Heinrich Haas

In a method for securing an object against unauthorized use, an interrogation unit () transmits an interrogation signal (s) and tests whether a response unit (), which is to be carried by an authorized user, responds to the interrogation signal with a response signal (r) that contains as information a code authorized for desecuring a security device (). If so, the security device is desecured. The securing method shall prevent unauthorized persons from establishing a radio link via relay stations between the interrogation unit () and the response unit () for providing the authorized code via this radio link without being noticed by the authorized user. The securing method prevents the desecuring of the security device () if the signal transit time of a signal transmitted as the interrogation signal (s) and received as the response signal (r) by the interrogation unit () during a monitoring time interval (t&#x2013;t) is greater than a prescribed value. The method is carried out in a keyless security system for securing motor vehicles against unauthorized use.

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Friedrichshafen, Germany

Karlheinz Mueller