Method for avoiding an unauthorized access to passive access-authorization system of a motor vehicle

• US 20060077042A1
• Filed: 09/29/2005
• Published: 04/13/2006
• Est. Priority Date: 09/29/2004
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hock, Alexander
• Application Number:
  US11/240,223
• Publication Number:
  US 20060077042A1
• Time in Patent Office: Days
• US Class Current: 340/10.400
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/63 Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A method for avoiding an unauthorized access to a passive access-authorization system of a motor vehicle having a vehicle-side transceiver and a portable transponder. In case of a query signal having a first radio reach, transmitted from the transceiver to the transponder, a second radio reach of a response signal transmitted by the transponder to the vehicle-side transceiver, is reduced.

Claims

1. A method for avoiding an unauthorized access to a passive access-authorization system of a motor vehicle having a vehicle-side transceiver and a portable transponder, the method comprising:

in case of a query signal having a first radio reach, transmitted from the transceiver to the transponder, reducing a second radio reach of a response signal transmitted by the transponder to the transceiver.

2. The method according to claim 1, wherein the second radio reach is reduced by lowering a transmission power of the transponder.

3. The method according to claim 1, wherein the second radio reach is reduced by at least one of (a) detuning a receiving antenna and (b) increasing a threshold value of a reception field strength of the vehicle-side transceiver.

4. The method according to claim 1, wherein the second radio reach is reduced by a radio-range limiter integrated in the transponder.

5. The method according to claim 1, wherein the first radio reach relates to a low-frequency signal transmitted from the transceiver of the motor vehicle, and the second radio reach relates to a high-frequency signal transmitted by the transponder.

6. The method according to claim 1, wherein the second radio reach is reduced to about the first radio reach.