Patent ID: 6867686
Filing Date: 2005-03-15
Classification: B60R,G07C,G08C

Abstract:
1. A motor vehicle access control system, comprising: a transmitting/receiving station configured for mounting in or on a motor vehicle; first and second transponders each disposed and configured to receive an interrogation code signal from said transmitting/receiving station and, upon receipt of said interrogation code signal, to transmit a coded answer signal; each of said transponders having: wherein said sub-carrier frequency generator of said first transponder generates a first sub-carrier frequency, said sub-carrier frequency generator of said second transponder generates a second-carrier frequency different from the first sub-carrier frequency, said first and second transponders utilize a common carrier frequency, and a transponder identification code of said first transponder is different from the transponder identification code of said second transponder; and said transmitting/receiving station is disposed and configured to substantially simultaneously receive and de-modulate the respective coded answer signals and to trigger an access authorization when a matching response code signal has been identified.