Method for initializing an anti-theft system for a motor vehicle

• US 6,211,776 B1
• Filed: 03/05/1999
• Issued: 04/03/2001
• Est. Priority Date: 03/05/1998
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Rohrl, Thomas, Glehr, Manfred
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): NGUYEN, HUNG T
• Application Number:
  US09/263,330
• Time in Patent Office: 760 Days
• Field of Search: 340/426, 340/425.5, 340/428, 340/430, 340/825.69, 340/825.31, 340/825.72, 340/825.57, 340/539, 340/514, 340/10.1, 340/10.4
• US Class Current: 340/426.16
• CPC Class Codes: B60R 25/04 operating on the propulsion system, e.g. engine or drive motor
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2009/00476 dynamically
• 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

An interrogation signal is emitted via one or more passenger compartment antennas of a motor vehicle. The transmit power of the emitted interrogation signal is changed until a portable transponder just still receives the interrogation signal if the transponder is located at a previously defined, fixed position. The transmit power which is set in this way is stored for the operation of the anti-theft system.

Claims

1. A method for initializing an anti-theft system, which comprises:

a) setting an initial transmit condition;

b) emitting an interrogation signal via a transceiver unit disposed in a motor vehicle and electrically connected to at least one antenna disposed on the motor vehicle;

c) receiving the interrogation signal in a portable response transmitter located at a previously defined fixed position and emitting a response signal in response to the interrogation signal;

d) receiving, evaluating, and comparing the response signal in a control unit of the transceiver unit with setpoint values;

e) changing the initial transmit condition according to a predefined algorithm in dependence on the response signal received; and

f) repeating steps b)-e) until the portable response transmitter just still receives the interrogation signal or just fails to receive the interrogation signal any more.

2. The method according to claim 1, which comprises storing determined transmit conditions as future transmit conditions in a transmit memory.

3. The method according to claim 1, which comprises using one of a transmit power, a transmit frequency and a phase of the interrogation signal as the initial transmit condition.

4. The method according to claim 1, which comprises:

disposing a first antenna formed of electrical coils near an ignition lock;

disposing a second antenna formed of electrical coils in a door of the motor;

disposing a third antenna formed of electrical coils in a vicinity of one of a side wall near a rear seat, a fuel tank a bumper, and a body panel of the motor vehicle; and

emitting the interrogation signal with each of the first antenna, the second antenna, and the third antenna.

5. The method according to claim 1, which comprises changing the initial transmit condition incrementally within a predefined range.

6. The method according to claim 1, which comprises changing the initial transmit condition continuously within a predefined range.

7. The method according to claim 1, which comprises providing and transmitting via a plurality of portable response transmitters a unique response code based on unique transmit conditions associated with each of the plurality of portable response transmitters.

8. The method according to claim 1, which comprises:

measuring a power of the interrogation signal via a measuring device of the portable response transmitter; and

transmitting via the portable response transmitter a measured power value to the transceiver unit disposed in the motor vehicle.

9. An anti-theft system, comprising:

at least one antenna disposed in a motor vehicle;

a transceiver unit disposed in the motor vehicle and electrically connected to said at least one antenna, said transceiver unit emitting via said at least one antenna an interrogation signal;

a portable response transmitter receiving the interrogation signal and responding by emitting a response signal; and

said portable response transmitter just still receives the interrogation signal or just fails to receive the interrogation signal any more;

said transceiver having a control unit for receiving, evaluating and comparing the response signal with setpoint values, said transceiver also having a transmit memory connected to said control unit for storing predetermined transmit conditions determined during an initialization phase.