Method of conducting keyless access authorization checks, e.g. for motor vehicles, involves evaluating difference between reference code signal and response signal characteristic

摘要

The method involves wireless communications between a base station (20) transmitter-receiver unit (22) and a mobile ID transponder (21) to check the access authorization of the person carrying the ID transponder. The transmitter-receiver unit sends a code signal that is received by the ID transponder, which responds with an action that is detectable by the transmitter-receiver unit to determine the distance between the base station and transponder. The distance measurement is based on a relative determination involving the difference in a signal characteristic dependent on signal transition time varying with distance between a reference code signal measured in the base station and the response signal. An Independent claim is also included for an arrangement for conducting keyless access authorization checks, e.g. for motor vehicles.