METHOD OF DETERMINING VEHICLE LOCATION FROM KEY FOB

• US 20110057817A1
• Filed: 09/04/2009
• Published: 03/10/2011
• Est. Priority Date: 09/04/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: BIONDO, WILLIAM A., LUST, ROBERT V., PROEFKE, DAVID T., McCALL, CLARK E.
• Granted Patent: US 8,547,253 B2
• Time in Patent Office: Days
• US Class Current: 340/989
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: H01Q 1/3241 particular used in keyless entry systems

Abstract

A method of indicating a proximity value representative of the distance between a key fob (202) and a vehicle (102) includes transmitting (304, 406, 504) at least one locate signal from the key fob (202) to the vehicle (102), transmitting (364, 468, 562) at least one response signal from the vehicle (102) to the key fob (202) in response to the at least one locate signal, performing (362, 462, 510) RSSI measurements of either the at least one locate signal or the at least one response signal, and displaying (318, 412, 514) the proximity value on the key fob (202) based on the RSSI measurements.

Claims

1. A method of indicating a proximity value representative of the distance between a key fob and a vehicle, comprising:

transmitting at least one locate signal from the key fob to the vehicle;

transmitting at least one response signal from the vehicle to the key fob in response to the at least one locate signal;

performing signal strength measurements of a received signal selected from the group consisting of the at least one locate signal and the at least one response signal; and

displaying the proximity value on the key fob based on the signal strength measurements.

2. The method of claim 1 wherein the vehicle includes a vehicle controller and the performing step comprising performing the signal strength measurements of the at least one locate signal within the vehicle controller.

3. The method of claim 1 wherein the key fob includes a key fob controller and the performing step comprising performing the signal strength measurements of the at least one response signal within the key fob controller.

4. The method of claim 1 further comprising calculating a rolling median of the signal strength measurements by the key fob controller.

5. The method of claim 1 further comprising repeating each of the steps a plurality of times.

6. The method of claim 1 wherein the transmitting at least one locate signal comprises transmitting a plurality of locate signals each having a unique power level, wherein the vehicle includes a vehicle controller and the performing step comprises measuring the signal strength value of each of the plurality of locate signals by the vehicle controller, and further comprising selecting one of the unique power levels by the vehicle controller, wherein the response signal includes the selected unique power level and the proximity value.

7. The method of claim 6 further comprising repeating each of the steps a plurality of times in succession.

8. The method of claim 1 wherein the transmitting at least one locate signal comprises transmitting at a maximum power level, wherein the transmitting at least one response signal comprises transmitting a plurality of signals each having a unique power level, wherein the performing signal strength measurements comprises determining an signal strength measurement for each of the plurality of signals, and further comprising calculating the proximity value based on at least one of the signal strength values within a preferred range of signal strength values.

9. The method of claim 8 further comprising repeating each of the steps a plurality of times in succession.

10. The method of claim 9 wherein the performing step comprises rejecting measurements that exceed a maximum rate of change.

11. An apparatus for indicating a proximity value representative of the distance between a key fob and a vehicle, comprising:

a first controller within the key fob configured for transmitting a locate signal to the vehicle, receiving a response signal from the vehicle in response to the locate signal, and performing signal strength measurements of the response signal; and

a display on the key fob configured for displaying the proximity value based on the signal strength measurements.

12. The system of claim 11 wherein the first controller is further configured to calculate a rolling median of the signal strength measurements.

13. The system of claim 11 wherein the first controller is further configured to transmit a plurality of locate signals and receive a plurality of response signals, each one of the response signals responsive to one of the transmit signals.

14. The system of claim 11 wherein the first controller is further configured to transmit a plurality of locate signals each having a unique power level.

15. The system of claim 14 wherein the vehicle includes a second controller configured to measure signal strength values of each of the plurality of locate signals and select one of the power levels, wherein the response signal includes the selected power level and the proximity value.

16. A method of indicating the distance between a key fob and a vehicle, comprising:

receiving a locate signal by the vehicle transmitted from the key fob; and

transmitting a plurality of signals from the vehicle to the key fob in response to receiving the locate signal, the distance indication being derived from signal strength measurements of one of the at least one locate signal or the plurality of signals.

17. The method of claim 16 wherein the vehicle includes a vehicle controller and further comprising performing the signal strength measurements of the at least one locate signal within the vehicle controller.

18. The method of claim 16 further comprising repeating each of the steps a plurality of times.

19. The method of claim 16 wherein the locate signal comprises a plurality of locate signals each having a unique power level and wherein the vehicle includes a vehicle controller, further comprising measuring a signal strength value of each of the plurality of locate signals by the vehicle controller, and further comprising selecting one of the unique power levels by the vehicle controller, wherein the response signal includes the selected unique power level and the proximity value.

20. The method of claim 16 wherein the transmitting step comprises a plurality of signals each having a unique power level.