Passive approach detection system and method using a unidirectional FOB

1. A method of passive approach detection, comprising:

transmitting a plurality of data signals corresponding to multiple power levels respectively from a fob device based on motion detected in the fob device; each of the plurality of data signals includes initial bytes encoded with a power level and transmitter identification (ID);

receiving one or more of the plurality of data signals at a receiver of a vehicle based on a distance between the fob device and the receiver;

filtering out signals at a secondary processor by comparing one or more of the plurality of data signals received to a predetermined list of signals valid for reception; and

transmitting a wake-up signal to a primary processor based on the comparison, the wake-up signal enabling the primary processor to transition from a sleep mode to a wake-up mode.

2. The method as in claim 1 , wherein the predetermined list of signals includes power levels and transmitter identifications (IDs) valid for reception.

3. The method as in claim 1 , wherein the method includes transmitting the plurality of data signals periodically for a predetermined amount of time in response to the fob device being in continuous motion past a predefined motion timeout, the fob device communicating to the receiver in a unidirectional manner.

4. The method as in claim 1 , wherein the method further includes:

determining whether one or more of the plurality of data signals received exceed a message frequency threshold; and

temporarily ignoring one or more of the plurality of data signals in the predetermined list of signals upon one or more of the plurality of data signals exceeding the message frequency threshold.

5. The method as in claim 4 , wherein one or more of the plurality of data signals received exceed the message frequency threshold when one or more of the plurality of data signals are continuously present for a predefined time period.

6. The method as in claim 1 , wherein the method further includes:

determining whether one or more of the plurality of data signals received signifies an approach by the fob device at the primary processor; and

activating one or more triggering events in one or more approach devices based on the determination.

7. The method of claim 6 , wherein one or more triggering events includes welcome lighting in the vehicle.

8. The method as in claim 6 , wherein determining whether one or more of the plurality of data signals received signifies the approach by the fob device by determining whether one or more of the plurality of data signals received meet predetermined approach criteria.

9. The method as in claim 6 , wherein one or more of the plurality of data signals received meet predetermined approach criteria when one or more transitions between power levels are detected.

10. The method as in claim 1 , wherein the method further comprises comparing a signal strength value encoded within each data signal received to valid signal strength values within the predetermined list of signals for reception.

11. A passive approach detection system, comprising:

a fob device configured to transmit a plurality of data signals corresponding to multiple power levels respectively based on motion detected in the fob device; each of the plurality of data signals includes initial bytes encoded with a power level and transmitter identification (ID);

a receiver of a vehicle communicatively coupled to the fob device, the receiver receives receive one or more of the plurality of data signals based on a distance between the fob device and the receiver;

a secondary processor communicatively coupled to the receiver, the secondary processor filters out signals by comparing one or more of the plurality of data signals received to a predetermined list of signals valid for reception; and

a primary processor communicatively coupled to the secondary processor, the secondary processor transmits a wake-up signal to the primary processor based on the comparison, the wake-up signal enables the primary processor to transition from a sleep mode to a wake-up mode.

12. The system as in claim 11 , wherein the predetermined list of signals includes power levels and transmitter identifications (IDs) valid for reception.

13. The system as in claim 11 , wherein the plurality of data signals are transmitted periodically for a predetermined amount of time in response to the fob device being in continuous motion past a predefined motion timeout, the fob device communicates to the receiver in a unidirectional manner.

14. The system as in claim 11 , wherein the primary processor determines whether one or more of the plurality of data signals received exceed a message frequency threshold and temporarily ignores one or more of the plurality of data signals in the predetermined list of signals upon one or more of the plurality of data signals exceeding the message frequency threshold.

15. The system as in claim 14 , wherein one or more of the plurality of data signals received exceed the message frequency threshold when one or more of the plurality of data signals are continuously present for a predefined time period.

16. The method as in claim 11 , wherein the primary processor determines whether one or more of the plurality of data signals received signifies an approach by the fob device and activates one or more triggering events in one or more approach devices based on the determination.

17. The system as in claim 16 , wherein the primary processor determines whether one or more of the plurality of data signals received signifies the approach by the fob device by determining whether one or more of the plurality of data signals received meet predetermined approach criteria, one or more of the plurality of data signals received meet predetermined approach criteria when one or more transitions between power levels are detected.

18. A passive approach detection system, comprising:

a fob device configured to transmit a plurality of data signals corresponding to multiple power levels respectively based on motion detected in the fob device; each of the plurality of data signals includes initial bytes encoded with a power level and transmitter identification (ID);

a receiver of a vehicle communicatively coupled to the fob device, the receiver receives one or more of the plurality of data signals based on a distance between the fob device and the receiver;

a secondary processor communicatively coupled to the receiver, the secondary processor filters out signals by comparing one or more of the plurality of data signals received to a predetermined list of signals valid for reception; and

a primary processor communicatively coupled to the secondary processor, the secondary processor transmits a wake-up signal to the primary processor based on the comparison, the wake-up signal enables the primary processor to transition from a sleep mode to a wake-up mode;

wherein the plurality of data signals are transmitted periodically for a predetermined amount of time in response to the fob device being in continuous motion past a predefined motion timeout, the fob device communicates to the receiver in a unidirectional manner.

19. The system as in claim 18 , wherein the primary processor determines whether one or more of the plurality of data signals received signifies an approach by the fob device and activates one or more triggering events in one or more approach devices based on the determination.