Daimler Chrysler Ag

Wolfgang Voss

Udo Knepper

Walter Ulke

Karl-Heinz M&uuml;ller

In a procedure for the provision of access authorization for an engine-driven vehicle, if there is an operator request for the provision of access authorization to an engine-driven vehicle, a bidirectional signal transmission using encoded transmission signals and an electronic key will be effected. From transmission units located on or in the vehicle, vehicle signals will be transmitted to the electronic key, and, from the electronic key, key signals will be returned as echo signals to the respective transmission units. The time difference between the vehicle signal and the key signals will be determined and evaluated. The position of the electronic key in relation to the vehicle will be determined by means of successive bidirectional signal transmissions between at least two transmission units and the electronic key as well as by evaluating the time differences; having determined the actual key position, a decision on access authorization to the vehicle will be made.

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Immenstaad, Germany

Wolfgang Voss