Access control system with limited evaluation of code and distance information
First Claim
1. An access control system for an object, particularly a vehicle, comprising:
- At least one base station with a transceiver device that transmits a wideband modulated interrogation signal, At least one transponder that has a modulation device, in order to modulate an auxiliary carrier signal, the frequency of which is re-keyed between a finite number of frequency positions, onto an interrogation signal received at a distance from the base station, and reflect it as a code-modulated response signal, and An evaluation device that is connected downstream from the transceiver device and that evaluates the response signal in sidebands of the keyed frequency positions with regard to code and distance.
2 Assignments
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Accused Products
Abstract
An access control system for an object, particularly a motor vehicle, comprises at least one base station with a transceiver device that transmits a wideband modulated interrogation signal, at least one transponder that has a modulation device, in order to modulate an auxiliary carrier signal, the frequency of which is changed between an infinite number of frequency positions, onto an interrogation signal received at a distance from the base station and reflect it as a code-modulated response signal, and an evaluation device that is connected after the transceiver device and that evaluates the response signal in sidebands of the changed frequency positions, with respect code and distance.
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Citations
20 Claims
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1. An access control system for an object, particularly a vehicle, comprising:
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At least one base station with a transceiver device that transmits a wideband modulated interrogation signal, At least one transponder that has a modulation device, in order to modulate an auxiliary carrier signal, the frequency of which is re-keyed between a finite number of frequency positions, onto an interrogation signal received at a distance from the base station, and reflect it as a code-modulated response signal, and An evaluation device that is connected downstream from the transceiver device and that evaluates the response signal in sidebands of the keyed frequency positions with regard to code and distance. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for operating an access control system for a vehicle that comprising the following steps:
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transmitting a wideband modulated interrogation signal from at least one base station;
receiving the interrogation signal by at least one transponder located at a distance from the base station, modulating the interrogation signal, in a modulation device, by a carrier signal, whose frequency is changed in the modulation device in relation to a code between a finite number of frequency positions, and reflected the modulated interrogation signal as a code-modulated answer signal, and evaluating, in at least one base station, the response signal in sidebands of the changed frequency positions in an evaluation unit with respect to code and distance. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification