Time-independent, event-based system for receiving and discriminating unique codes from multiple transmitters and method for doing the same

• US 6,215,389 B1
• Filed: 04/14/1999
• Issued: 04/10/2001
• Est. Priority Date: 04/14/1999
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Schmidt, David J.
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Bangachon, William L
• Application Number:
  US09/291,348
• Time in Patent Office: 727 Days
• Field of Search: 340/442, 340/447, 340/448, 340/443, 340/825.3, 340/5.1, 340/5.27
• US Class Current: 340/5.1
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A time-independent, event-based system for receiving and discriminating unique codes from multiple transmitters has an event-based detection cycle instead of a time-based detection cycle. The system detects received ID codes from multiple transmitters and compares the received ID codes with registers for ID codes in an array in memory. Counters corresponding to the stored ID codes increment each time there is a match between the received ID code and the stored ID code. After a predetermined total number of increments, the system evaluates the received signals to discriminate between ID codes received from desired transmitters and those from undesired transmitters before resetting the counter. Because the system is event based and not a function of time, it will operate over a wide range of time cycles.

Claims

1. A method for discriminating among ID codes from a group of desired transmitters and ID codes from undesired transmitters wherein the number of transmissions from undesired transmitters is less than the number of transmissions from desired transmitters, each transmitter having a unique ID code, wherein an array has registers adapted to store ID codes corresponding to the group of desired transmitters, the method comprising the steps of:

providing a main array having a plurality of main registers for storing a plurality of main ID codes;

providing a plurality of main ID code counters each associated with one of the plurality of main registers of the main array;

incrementing an appropriate one of the main ID code counters whenever a received ID code is stored in one of the main registers or matches one of the main ID codes already stored in one of the main registers; and

clearing any of the main registers whose associated main ID code counter is below a predetermined main ID code counter threshold when the sum of the main ID code counters exceeds a predetermined main event counter threshold, wherein ID codes from undesired transmitters can be cleared from the main array.

2. The method of claim 1, further comprising the steps of:

providing an auxiliary array having a plurality of auxiliary registers for storing a plurality of auxiliary ID codes;

providing a plurality of auxiliary ID code counters each associated with one of the plurality of auxiliary registers of the auxiliary array;

incrementing an appropriate one of the auxiliary ID code counters whenever the received ID code is stored in one of the auxiliary registers or matches one of the auxiliary ID codes already stored in one of the auxiliary registers; and

clearing any of the auxiliary registers whose associated auxiliary ID code counter is below a predetermined auxiliary ID code counter threshold when the sum of the auxiliary ID code counters exceeds a predetermined auxiliary event counter threshold, wherein any of the auxiliary registers that are not cleared provide a secondary source of preselected ID codes for the main array.

3. The method of claim 2, further comprising the steps of:

determining whether the auxiliary array has fewer than a predetermined number of the auxiliary ID codes; and

storing the received ID code in the auxiliary array as a new auxiliary ID code if the auxiliary array has fewer than the predetermined number of the auxiliary ID codes.

4. The method of claim 3, wherein the determining step includes checking how many of the auxiliary ID code counters are below the auxiliary ID code counter threshold.

5. The method of claim 2, further comprising the step of:

resetting the main ID code counters, the auxiliary ID code counters, and the auxiliary array if all of the main ID code counters associated with the main ID codes in the main array meet or exceed the main ID code counter threshold.

6. The method of claim 3, further comprising the steps of:

resetting the main ID code counters, the auxiliary ID code counters, and the auxiliary array if all of the main ID code counters associated with the main ID codes in the main array meet or exceed the main ID code counter threshold;

determining whether the number of the clear main registers is equal to the number of the new auxiliary ID codes stored in the auxiliary array if at least one of the main ID code counters falls below the main ID code counter threshold;

moving the stored new auxiliary ID codes to the clear main registers in the main array when the number of the clear main registers is equal to the number of the new auxiliary ID codes; and

resetting the main ID code counters, the auxiliary ID code counters, and the auxiliary array after the moving step.

7. The method of claim 6, wherein the step of determining whether the auxiliary array has fewer than the predetermined number of auxiliary ID codes includes checking how many of the auxiliary ID code counters are below the auxiliary ID code counter threshold.

8. The method of claim 1, wherein a single main event counter is provided to sum the main ID code counters.

9. The method of claim 2, wherein a single auxiliary event counter is provided to sum the auxiliary ID code counters.

10. An apparatus for discriminating between ID codes from a group of desired transmitters and ID codes from undesired transmitters, each transmitter having a unique ID code, comprising:

a receiver for receiving a plurality of ID codes from a plurality of transmitters;

a memory having a main array that includes a plurality of main registers adapted to store a plurality of main ID codes corresponding to the group of desired transmitters; and

a controller for providing;

a plurality of main ID code counters each associated with one of the plurality of main registers of the main array, wherein an appropriate one of the main ID code counters is incremented whenever a received ID code is stored in one of the main registers or matches one of the main ID codes already stored in one of the main registers; and

a main threshold detector that causes the controller to clear any of the main registers whose associated main ID code counter is below a predetermined main ID code counter threshold when the sum of the main ID code counters exceeds a predetermined main event counter threshold.

11. The apparatus of claim 10, wherein the memory further includes an auxiliary array having a plurality of auxiliary registers adapted to store a plurality of auxiliary ID codes, and wherein the controller further provides:

a plurality of auxiliary ID code counters each associated with one of the plurality of auxiliary registers of the auxiliary array, wherein an appropriate one of auxiliary ID code counters is incremented whenever the received ID code is stored in one of the auxiliary registers or matches one of the auxiliary ID codes already stored in one of the auxiliary registers; and

an auxiliary threshold detector that causes the controller to clear any of the auxiliary registers whose associated auxiliary ID code counter is below a predetermined auxiliary ID code counter threshold when the sum of the auxiliary ID code counters exceeds a predetermined auxiliary event counter threshold, wherein any of the auxiliary registers that are not cleared provide a secondary source of preselected ID codes for the main array.

12. The apparatus of claim 11, wherein the controller checks the memory to determine whether the auxiliary array has fewer than a predetermined number of the auxiliary ID codes and stores the received ID code in the auxiliary array as a new auxiliary ID code if the auxiliary array has fewer than the predetermined number of the auxiliary ID codes.

13. The apparatus of claim 12, wherein the controller checks how many of the auxiliary ID code counters are below the auxiliary ID code counter threshold.

14. The apparatus of claim 11, wherein the controller resets the main ID code counters, the auxiliary ID code counters, and the auxiliary array if all of the main ID code counters associated with the main ID codes in the main array meet or exceed the main ID code counter threshold.

15. The apparatus of claim 12, wherein the controller;

resets the main ID code counters, the auxiliary ID code counters, and the auxiliary array if all of the main ID code counters associated with the main ID codes in the main array meet or exceed the main ID code counter threshold;

determines whether the number of inactive main ID codes is equal to the number of the new auxiliary ID codes stored in the auxiliary array if at least one of the main ID code counters falls below the main ID code counter threshold;

removes the inactive main ID codes if the number of inactive main ID codes is equal to the number of the new auxiliary ID codes;

moves the new auxiliary ID codes to the main array to replace the removed inactive main ID codes; and

resets the main ID code counters, the auxiliary ID code counters, and the auxiliary array after moving the new auxiliary ID codes to the main array.

16. The apparatus of claim 15, wherein the controller determines whether the auxiliary array has fewer than the predetermined number of auxiliary ID codes by determining how many of the auxiliary ID code counters are below the auxiliary ID code counter threshold.

17. The apparatus of claim 15, further comprising;

a user indicator coupled to the controller to indicate an error if the controller determines that the number of the inactive main ID codes is not equal to the number of the new auxiliary ID codes stored in the auxiliary array if at least one of the main ID code counters falls below the main ID code counter threshold.

18. The apparatus of claim 10, wherein a single main event counter provides the sum of the main ID code counters.

19. The apparatus of claim 11, wherein a single auxiliary event counter provides the sum of the auxiliary ID code counters.