Noise alarm timer function for three-axis low frequency transponder

• US 7,209,030 B2
• Filed: 03/14/2005
• Issued: 04/24/2007
• Est. Priority Date: 04/23/2004
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Nolan, James B., Lee, Thomas Youbok, Vernier, Steve, Lamphier, Alan
• Primary Examiner(s): Crosland; Donnie L.
• Application Number:
  US11/079,787
• Publication Number:
  US 20050237220A1
• Time in Patent Office: 771 Days
• Field of Search: 340/538.12, 340/426.36, 340/10.33
• US Class Current: 340/426.36
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: B60R 25/406 Power supply in the remote key
• CPC Class Codes: G07C 2009/00769 with data transmission performed by wireless means
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A remote keyless entry (RKE) transponder has a noise alarm timer having a time interval used for determining whether a received signal meets a predefined condition within a time interval. If the received signal meets the predefined condition within the time interval, the noise alarm timer is disabled and the RKE transponder circuits are enabled so that normal operation in processing the desired signal commences. If the received signal does not meet the predefined condition within the time interval the noise alarm timer issues an alert signal, whereby appropriate action may be taken such as adjusting the channel input sensitivity, disabling a channel, or placing the RKE transponder into a sleep mode in order to reduce the power consumption caused by undesired input signals. A smart wake-up filter determines whether or not the input signal meets the predefined condition within the time interval.

Claims

1. A method for reducing false wake-up of a remote keyless entry (RKE) transponder due to unwanted input signal, said method comprising the steps of:

receiving an input signal with an analog front-end (AFE) of a remote keyless entry (RKE) transponder;

starting a noise alarm timer upon receiving the input signal, wherein the noise alarm timer has a timeout period; and

determining whether the received signal meets a predefined criteria within the timeout period, wherein

if the received signal meets the predefined criteria within the timeout period then disable the noise alarm timer, and

if the received signal does not meet the predefined criteria within the timeout period then generate a noise alarm.

2. The method according to claim 1, wherein the timeout period is about 32 milliseconds.

3. The method according to claim 1, wherein the predefined criteria is determined with a smart wake-up filter.

4. The method according to claim 1, wherein the predefined criteria is determined with a digital discrimination filter.

5. The method according to claim 1, further comprising the step of waking-up an external control device for accepting signal data when the received signal meets the predefined criteria within the timeout period.

6. The method according to claim 1, further comprising the step of waking-up an external control device when the noise alarm is generated so that the external control device will adjust a parameter of the AFE so as to substantially ignore the signal not meeting the predefined criteria within the timeout period.

7. The method according to claim 6, wherein the parameter is amplifier gain of the AFE.

8. The method according to claim 7, wherein the amplifier gain of the AFE is dynamically adjusted.

9. The method according to claim 6, further comprising the steps of modifying the predefined criteria of the digital discrimination filter and then determining if a received signal meets the modified predefined criteria within the timeout period.

10. The method according to claim 1, wherein the timeout period is calculated from an AFE internal oscillator frequency.

11. The method according to claim 1, wherein the predefined criteria is met when within the timeout period the received signal is substantially on for a predefined on period and substantially off for a predefined off period.

12. The method according to claim 1, further comprising the step of putting the AFE in a sleep mode when the noise alarm is generated.

13. The method according to claim 1, further comprising the step of enabling the noise alarm timer when there is no received signal.

14. The method according to claim 1, further comprising the step of resetting the noise alarm when there is substantially no received signal.

15. A method for reducing false wake-up of a multi-channel remote keyless entry (RKE) transponder due to unwanted input signal, said method comprising the steps of:

receiving an input signal with a multi-channel analog front-end (AFE) of a remote keyless entry (RKE) transponder;

starting a noise alarm timer upon receiving the input signal, wherein the noise alarm timer has a timeout period; and

determining whether the received signal meets a predefined criteria within the timeout period, wherein

if the received signal meets the predefined criteria within the timeout period then disable the noise alarm timer, and

if the received signal does not meet the predefined criteria within the timeout period then generate a noise alarm.

16. The method according to claim 15, wherein the timeout period is about 32 milliseconds.

17. The method according to claim 15, wherein the predefined criteria is determined with a smart wake-up filter.

18. The method according to claim 17, wherein the smart wake-up filter has programmable parameters.

19. The method according to claim 18, wherein the programmable parameters are stored in a configuration register.

20. The method according to claim 15, wherein the predefined criteria is determined with a digital discrimination filter.

21. The method according to claim 15, further comprising the step of waking-up an external control device for accepting signal data when the received signal meets the predefined criteria within the timeout period.

22. The method according to claim 15, further comprising the step of waking-up an external control device when the noise alarm is generated so that the external control device will adjust a parameter of the AFE so as to substantially ignore the signal not meeting the predefined criteria within the timeout period.

23. The method according to claim 22, wherein the parameter is amplifier gain of an input channel of the AFE.

24. The method according to claim 23, wherein the gain of the channel of the AFE is dynamically adjusted.

25. The method according to claim 22, further comprising the steps of modifying the predefined criteria of the digital discrimination filter and then determining if a received signal meets the modified predefined criteria within the timeout period.

26. The method according to claim 15, wherein the timeout period is calculated from an AFE internal oscillator frequency.

27. The method according to claim 15, wherein the predefined criteria is met when within the timeout period the received signal is substantially on for a predefined on period and substantially off for a predefined off period.

28. The method according to claim 15, further comprising the step of a disabling at least one input channel of the AFE when a noise alarm is generated.

29. The method according to claim 15, further comprising the step of disabling each channel of the AFE which receives a signal that does not meet the predefined criteria within the timeout period.

30. The method according to claim 15, wherein the received signal is at a frequency from about 100 kHz to about 400 kHz.

31. The method according to claim 15, wherein the optimum received signal is at a frequency of about 125 kHz.

32. The method according to claim 15, wherein the multi-channel AFE comprises three channels.

33. A remote keyless entry (RKE) transponder having reduced false wake-up due to unwanted input signal, comprising:

an analog front-end (AFE); and

a noise alarm timer having a timeout period, wherein when an input signal is received by the AFE the noise alarm timer begins a timeout period during which time the received input signal must meet a predefined criteria, otherwise a noise alarm is generated.

34. The RKE transponder according to claim 33, wherein the AFE comprises an amplifier and a signal detector.

35. The RKE transponder according to claim 33, further comprising a smart wake-up filter for determining whether the received signal meets the predefined criteria.

36. The RKE transponder according to claim 33, further comprising an external control device adapted to receive the generated noise alarm, whereby the external control device adjusts a parameter of the AFE so as to substantially ignore the received signal not meeting the predefined criteria within the timeout period.

37. The RKE transponder according to claim 36, wherein the parameter is amplifier gain of the AFE.

38. The RKE transponder according to claim 37, wherein the amplifier gain of each channel of the AFE is dynamically adjusted by the external control device.

39. The RKE transponder according to claim 36, wherein the external control device is selected from the group consisting of digital processor, microcontroller, microprocessor, digital signal processor, application specific integrated circuit (ASIC) and programmable logic array (PLA).

40. The RKE transponder according to claim 33, wherein the AFE is put into a sleep mode when the noise alarm is generated.

41. The RKE transponder according to claim 40, wherein when the AFE is in the sleep mode it consumes a minimum amount of power.

42. The RKE transponder according to claim 33, wherein the noise alarm is reset when there is substantially no received signal.

43. The RKE transponder according to claim 33, wherein the AFE comprises a plurality of input channels.

44. The RKE transponder according to claim 43, wherein the plurality of input channels comprises three input channels.

45. The RKE transponder according to claim 43, wherein the AFE receives signals at about 125 kHz.

46. The RKE transponder according to claim 43, wherein the AFE is adapted to receive signals from about 100 kHz to about 400 kHz.

47. The RKE transponder according to claim 33, wherein a signal channel of the AFE is optionally disabled when a noise alarm is generated by an external device.

48. The RKE transponder according to claim 43, wherein each signal channel output of the plurality of signal channels is disabled if a received signal does not meet the predefined criteria within the timeout period.