The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 12, 2004
Filed:
Apr. 12, 2001
Detlev Kramer, Schwerte, DE;
Volker Pretzlaff, Iserlohn, DE;
Rainer Vens, Dortmund, DE;
Paul Vogels, Dortmund, DE;
Michael Fromm, Dortmund, DE;
Dirk Wolf, Dortmund, DE;
Peter Raab, Hagen, DE;
Leopold Kostal GmbH & Co. KG, Ludenscheid, DE;
Abstract
A method and device for checking keyless vehicle access authorization of an operator. The method includes transmitting a code signal from a base station to a mobile identification (ID) transmitter carried by the operator. In response to receiving the code signal, the ID transmitter performs an action which is indicative of a reply signal that is detectable by the base station. The difference of a signal characteristic between a reference code signal monitored at the base station and the reply signal received by the base station is then determined. The signal characteristic correlates with signal propagation time and changes as a function of the distance between the base station and the ID transmitter. The distance between the base station and the ID transmitter is then determined on the basis of a relative determination based on the difference of the signal characteristic between the reference code signal and the reply signal.