Passive entry and/or passive go system and associated operating method

• US 8,525,672 B2
• Filed: 04/25/2007
• Issued: 09/03/2013
• Est. Priority Date: 04/25/2006
• Status: Active Grant

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Moser, Daniel, Moser, Helmut
• Primary Examiner(s): Lim, Steven
• Assistant Examiner(s): Mahase, Pameshanand
• Application Number:
  US11/790,493
• Publication Number:
  US 20070257771A1
• Time in Patent Office: 2,323 Days
• Field of Search: 340/5.61, 455/456.1, 455/572.1
• US Class Current: 340/539.21
• CPC Class Codes: B60R 2325/105 Radio frequency identification data [RFID]
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2009/00547 starting ignition
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A passive entry and/or passive go system and am associated operating method is provided. According to an embodiment of the invention, the following steps are performed in an electronic key of the passive entry and/or passive go system: generation of a reference input value, supplying the antenna circuit with the reference input value, measurement of the characteristic parameters, while the antenna circuit is supplied with the reference input value, storage of the characteristic parameters, measurement of a first output value of the antenna circuit, and determination of the field strength from the first output value and the characteristic parameters, whereby an effect of the characteristic parameters on the field strength is compensated. Use, for example, in motor vehicles.

Claims

1. A method comprising:

receiving a carrier signal associated with a base station using an antenna of an antenna circuit of an electronic key;

calibrating, at the electronic key, an output value output from the antenna circuit by measuring characteristic parameters of the antenna circuit using a reference input value generated by the electronic key as an input to the antenna circuit;

calculating, at the electronic key, an actual field strength of the carrier signal using the calibrated output value;

determining, at the electronic key, a distance between the base station and the electronic key based on the actual field strength; and

transmitting, at the electronic key and based on a determination that the distance between the base station and the electronic key is within a pre-specified range, a signal to the base station, receipt of the signal at the base station causing the base station to initiate a function performed by an apparatus.

2. The method of claim 1, further comprising determining, at the electronic key, the function performed by the apparatus based on the distance.

3. The method of claim 1, wherein calculating the actual field strength further comprises calculating a quotient formed from the output value output from the antenna circuit and an output value resulting from the reference input value being used as the input to the antenna circuit.

4. The method of claim 1, wherein:

the reference input value comprises a reference voltage; and

calibrating the output value output from the antenna circuit further comprises generating, at the electronic key, the reference voltage at a reference frequency derived from a frequency of the carrier signal, the generating of the reference voltage being performed by an oscillator of the electronic key.

5. The method of claim 1, wherein:

the antenna is one of a plurality of perpendicular antennas of the electronic key; and

the method further comprises;

calculating, for each of the other antennas in the plurality of antennas, a corresponding actual field strength of the carrier signal; and

determining, at the electronic key, a position of the electronic key relative to the base station through superposition of the actual field strength for the antenna and the corresponding actual field strengths for each of the other antennas in the plurality of antennas.

20. The method of claim 1, further comprising switching, at the antenna circuit, between providing the reference input value and receiving the output value.

21. The method of claim 1, wherein the reference input value comprises one or more of:

a reference voltage; and

a reference current.

6. An electronic key comprising:

an antenna circuit operable to receive using an antenna a carrier signal associated with a base station; and

one or more non-transitory computer-readable storage media that embody logic that is operable when executed to;

calibrate an output value output from the antenna circuit by measuring characteristic parameters of the antenna circuit using a reference input value generated by the electronic key as an input to the antenna circuit;

calculate an actual field strength of the carrier signal using the calibrated output value;

determine a distance between the base station and the electronic key based on the actual field strength; and

transmit, based on a determination that the distance between the base station and the electronic key is within a pre-specified range, a signal to the base station, receipt of the signal at the base station causing the base station to initiate a function performed by an apparatus.

7. The electronic key of claim 6, wherein:

the electronic key further comprises an oscillator;

the reference input value comprises a reference voltage; and

the logic when executed is further operable to generate the reference voltage at a frequency derived from a frequency of the carrier signal, the generating of the reference voltage being performed by the oscillator of the electronic key.

8. The electronic key of claim 6, wherein the logic when executed is operable to calculate the actual field strength of the carrier signal by performing operations comprising calculating a quotient formed from the output value output from the antenna circuit and an output value resulting from the reference input value being used as the input to the antenna circuit.

9. The electronic key of claim 6, wherein the logic when executed is further operable to determine the function performed by the apparatus based on the distance between the base station and the electronic key.

10. The electronic key of claim 6, wherein:

the antenna is one of a plurality of perpendicular antennas of the electronic key; and

the logic when executed is further operable to;

calculate, for each of the other antennas in the plurality of antennas, a corresponding actual field strength of the carrier signal; and

determine a position of the electronic key relative to the base station through superposition of the actual field strength for the antenna and the corresponding actual field strengths for each of the other antennas in the plurality of antennas.

11. The electronic key of claim 6, wherein the logic is further operable to switch between providing the reference input value and receiving the output value at the antenna circuit.

12. The electronic key of claim 6, wherein the function initiated by the base station is unlocking a motor vehicle.

22. The electronic key of claim 6, wherein the reference input value comprises one or more of:

a reference voltage; and

a reference current.

13. One or more non-transitory computer-readable storage media that embody logic that is operable when executed to:

calibrate an output value output from an antenna circuit of an electronic key by measuring characteristic parameters of the antenna circuit using a reference input value generated by the electronic key as an input to the antenna circuit, the antenna circuit having received using an antenna a carrier signal associated with a base station;

calculate an actual field strength of the carrier signal using the calibrated output value;

determine a distance between the base station and the electronic key based on the actual field strength; and

transmit, based on a determination that the distance between the base station and the electronic key is within a pre-specified range, a signal to the base station, receipt of the signal at the base station causing the base station to initiate a function performed by an apparatus.

14. The one or more non-transitory computer-readable storage media of claim 13, wherein:

the reference input value comprises a reference voltage; and

the logic when executed is further operable to generate the reference voltage at a frequency derived from a frequency of the carrier signal, the generating of the reference voltage being performed by an oscillator of the electronic key.

15. The one or more non-transitory computer-readable storage media of claim 13, wherein the logic when executed is operable to calculate the actual field strength of the carrier signal by performing operations comprising calculating a quotient formed from the output value output from the antenna circuit and an output value resulting from the reference input value being used as the input to the antenna circuit.

16. The one or more non-transitory computer-readable storage media of claim 13, wherein the logic when executed is further operable to determine the function performed by the apparatus based on the distance between the base station and the electronic key.

17. The one or more non-transitory computer-readable storage media of claim 13, wherein:

the antenna is one of a plurality of perpendicular antennas of the electronic key; and

the logic when executed is further operable to;

calculate, for each of the other antennas in the plurality of antennas, a corresponding actual field strength of the carrier signal; and

determine a position of the electronic key relative to the base station through superposition of the actual field strength for the antenna and the corresponding actual field strengths for each of the other antennas in the plurality of antennas.

18. The one or more non-transitory computer-readable storage media of claim 13, wherein the logic is further operable to switch between providing the reference input value and receiving the output value at the antenna circuit.

19. The one or more non-transitory computer-readable storage media of claim 13, wherein the function initiated by the base station is unlocking a motor vehicle.

23. The one or more non-transitory computer-readable storage media of claim 13, wherein the reference input value comprises one or more of:

a reference voltage; and

a reference current.