Methods and apparatus for intrusion detection having improved immunity to false alarms

• US 5,475,365 A
• Filed: 12/02/1994
• Issued: 12/12/1995
• Est. Priority Date: 01/28/1993
• Status: Expired due to Term

• Current Assignee: C & K Systems, Inc. (Honeywell International Inc.)
• Original Assignee: C & K Systems, Inc. (Honeywell International Inc.)
• Inventors: Hoseit, Paul M., Whiting, Gordon S.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): Wu, Daniel J.
• Application Number:
  US08/348,759
• Time in Patent Office: 375 Days
• Field of Search: 340/508, 340/522, 340/523, 340/526, 340/506, 340/541, 340/565, 340/552, 367/93, 367/94
• US Class Current: 340/522
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence
• CPC Class Codes: G08B 29/185 Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system

Abstract

A multisensor intrusion detection system having greatly improved immunity to false alarms is disclosed. This system employs a first sensor for sensing an intrusion in a volume of space by a first physical phenomenon and a second sensor for detecting an intrusion in the volume of space by a second physical phenomenon different from the first physical phenomenon. The first sensor generates a first signal in response to the detection of an intrusion into the volume of space, and the second sensor generates a second signal in response to a detection of an intrusion. A microcontroller generates an alarm signal upon the occurrence of one first signal and one second signal within a first interval, the occurrence of another first signal within a subsequent second interval and the occurrence of another second signal within a third subsequent interval.

Claims

1. An intrusion detection system comprising:

a first detecting means for detecting an intrusion in a volume of space by a first physical phenomenon and for generating a first signal in response to each detection of said intrusion;

a second detecting means for detecting an intrusion in said volume of space by a second physical phenomenon different from the first phenomenon, for generating a second signal in response to the detection of said intrusion; and

logic means for generating an alarm signal in response to the occurrence of one first signal in response to one detection and one second signal in response to one detection within a first interval, the occurrence of another first signal within a second interval said second interval subsequent to said first interval, and the occurrence of another second signal in response to another detection within a third interval said third interval subsequent to said second interval.

2. The system of claim 1 wherein said first detecting means comprises:

a passive infrared detector.

3. The system of claim 2 wherein said second detecting means comprises:

a microwave detector.

4. The system of claim 1 wherein said first detecting means comprises:

a microwave detector.

5. The system of claim 4 wherein said second detecting means comprises:

a passive infrared detector.

6. The system of claim 1 wherein said logic means comprises a microcontroller.

7. The system of claim 1 wherein said logic means for generating an alarm signal further comprises:

timing means for limiting the duration of said alarm signal.

8. A method of detecting an intrusion within a volume of space comprising the steps of:

detecting an intrusion within a volume of space by a first physical phenomenon;

generating a first signal in response to the detection of said intrusion by said first physical phenomenon;

detecting an intrusion within said volume of space by a second physical phenomena, different from the first phenomena;

generating a second signal in response to the detection of said intrusion by said second physical phenomena;

generating an alarm signal in response to the occurrence of one first signal and one second signal within a first interval, the occurrence of another first signal within a second interval said second interval subsequent to said first interval, and the occurrence of another second signal within a third interval said third interval subsequent to said second interval.

9. The method of claim 8 wherein said first physical phenomena is infrared radiation.

10. The method of claim 9 wherein said second physical phenomenon is doppler shift microwave radio frequency.

11. The method of claim 8 wherein said first physical phenomenon is doppler shift.

12. The method of claim 11 wherein said second physical phenomenon is infrared radiation.

13. The method of claim 8 further comprising the step of:

limiting the duration of the alarm signal.

14. An intrusion detection system comprising:

a first sensor for sensing an intrusion in a volume of space by a first physical phenomenon and for generating a first signal in response to the detection of said intrusion;

a second sensor for sensing an intrusion in said volume of space by a second physical phenomenon different from the first phenomenon, for generating a second signal in response to the detection of said intrusion; and

a microcontroller for generating an alarm signal in response to the occurrence of one first signal and one second signal within a first interval, the occurrence of another first signal within a second interval said second interval subsequent to said first interval, and the occurrence of another second signal within a third interval said third interval subsequent to said second interval.

15. The system of claim 14 wherein said first sensor comprises:

a passive infrared detector.

16. The system of claim 15 wherein said second sensor comprises:

a passive infrared detector.

17. The system of claim 14 wherein said first sensor comprises:

a microwave detector.

18. The system of claim 17 wherein said second sensor comprises:

a passive infrared detector.

19. A method of detecting an intrusion within a volume of space comprising the steps of:

detecting an intrusion within a volume of space by a first physical phenomenon;

generating a first signal in response to the detection of said intrusion by said first physical phenomenon;

detecting an intrusion within said volume of space by a second physical phenomena, different from the first phenomena;

generating a second signal in response to the detection of said intrusion by said second physical phenomena;

generating an alarm signal in response to the occurrence of at least one first signal and at least one second signal within a first interval, the occurrence of one of another first signal and another second within a second interval said second interval subsequent to said first interval, and the occurrence of one of another first signal and another second signal within a third interval said third interval subsequent to said second interval.

20. An intrusion detection system comprising:

a first detecting means for detecting an intrusion in a volume of space by a first physical phenomenon and for generating a first signal in response to each detection of said intrusion;

a second detecting means for detecting an intrusion in said volume of space by a second physical phenomenon different from the first physical phenomenon and for generating a second signal in response to the detection of said intrusion; and

logic means for generating an alarm signal in response to the occurrence of one first signal in response to one detection and one second signal in response to one detection within a first interval of time; and

the logic means also generating an alarm signal in response to the occurrence of a plurality of first signals generated within a second interval of time.

21. The system of claim 20 wherein said first detecting means comprises:

a passive infrared detector.

22. The system of claim 21 wherein said second detecting means comprises:

a microwave detector.

23. The system of claim 20 wherein said first detecting means comprises:

a microwave detector.

24. The system of claim 23 wherein said second detecting means comprises:

a passive infrared detector.

25. The system of claim 20 wherein said logic means comprises a microcontroller.

26. The system of claim 20 wherein said logic means for generating an alarm signal further comprises:

timing means for limiting said alarm signal in duration.

29. The method of claim 25 wherein said second physical phenomenon is doppler shift microwave radio frequency.

27. A method of detecting an intrusion within a volume of space comprising the steps of:

detecting an intrusion within a volume of space by s first physical phenomenon;

generating a first signal in response to the detection of said intrusion by said first physical phenomenon;

detecting an intrusion within said volume of space by a second physical phenomenon;

generating a second signal in response to the detection of said intrusion by said second physical phenomenon;

generating an alarm signal in response to the occurrence of one first signal and one second signal within a first interval of time; and

generating an alarm signal in response to the occurrence of a plurality of first signals generated within a second interval of time.

28. The method of claim 27 wherein said first physical phenomena is infrared radiation.

30. The method of claim 27 wherein said first physical phenomenon is doppler shift.

31. The method of claim 30 wherein said second physical phenomenon is infrared radiation.

32. The method of claim 27 further comprising the step of:

limiting the alarm signal in duration.

33. An intrusion detection system comprising:

a first sensor for sensing an intrusion in a volume of space by a first physical phenomenon and for generating a first signal in response to the detection of said intrusion;

a second sensor for sensing an intrusion in said volume of space by a second physical phenomenon different from the first physical phenomenon and for generating a second signal in response to the detection of said intrusion; and

a microcontroller for generating an alarm signal in response to the occurrence of one first signal and one second signal in response to one detection within a first interval of time; and

the microcontroller also generating an alarm signal in response to the occurrence of a plurality of first signals generated within a second interval of time.

34. The system of claim 33 wherein said first sensor comprises:

a passive infrared detector.

35. The system of claim 34 wherein said second sensor comprises:

a passive infrared detector.

36. The system of claim 33 wherein said first sensor comprises:

a microwave detector.

37. The system of claim 36 wherein said second sensor comprises:

a passive infrared detector.

38. A method of detecting an intrusion within a volume of space comprising the steps of:

detecting an intrusion within a volume of space by s first physical phenomenon;

generating s first signal in response to the detection of said intrusion by said first physical phenomenon;

detecting an intrusion within said volume of space by a second physical phenomenon, different from the first phenomenon;

generating a second signal in response to the detection of said intrusion by said second physical phenomenon;

generating an alarm signal in response to the occurrence of at least one first signal and at least one second signal within a first interval of time; and

generating an alarm signal in response to the occurrence of a plurality of first signals generated within a second interval of time.