System and method for improving infrared detector performance in dual detector system

• US 20080218340A1
• Filed: 03/07/2007
• Published: 09/11/2008
• Est. Priority Date: 03/07/2007
• Status: Active Grant

• Current Assignee: Gregory Royer
• Original Assignee: Robert Bosch GmbH, Robert Bosch LLC (Robert Bosch GmbH)
• Inventors: Royer, Gregory
• Granted Patent: US 7,679,509 B2
• Time in Patent Office: Days
• US Class Current: 340/567
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/886 for alarm systems alarms with electrical actuation G08B13/22
• CPC Class Codes: G08B 13/2494 by interference with electro-magnetic field distribution combined with other electrical sensor means, e.g. microwave detectors combined with other sensor means
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence
• CPC Class Codes: G08B 29/20 Calibration, including self-calibrating arrangements

Abstract

Embodiments of the present invention is directed to a method and system for use of ranging MW to reduce dual (MW/PIR) intrusion detector false alarms. A Doppler microwave system may be provided that is capable of detecting an object range and adjusting the sensitivity of the PIR detector to account for object size and range. Multiple range limited MW stages may be configured for different ranges to determine the general range of the moving object. Based on signal levels present on these MW stages, an approximate object range is determined. The sensitivity of the PIR is then adjusted based on a PIR sensitivity vs. object range function that is optimized to alarm on humans and ignore small animals and insects.

Claims

1. A system for improving false alarm immunity for a dual intrusion detector, the dual intrusion detector including at least one microwave sensor and at least one passive infrared sensor, the system comprising:

multiple range bins for classifying microwave signals;

a range determination module for estimating a target range based on a state of each of the multiple range bins; and

an infrared sensitivity determination mechanism for determining an optimal infrared sensor sensitivity level based on the estimated target range.

2. The system of claim 1, further comprising dynamically adjusting an infrared sensitivity level to a predetermined threshold upon determination of the target range.

3. The system of claim 1, further comprising an alarm selection component for determining whether to trigger an alarm based on microwave sensor and passive infrared sensor output.

4. The system of claim 1, wherein the multiple range bins comprise at least a short range bin and a long range bin.

5. The system of claim 4, wherein the multiple range bins further comprise an insect range bin and a mid-range bin.

6. The system of claim 5, wherein the insect range bin is capable of detecting insects in an immediate vicinity of the intrusion detector.

7. The system of claim 6, wherein when the insect bin detects a target, the infrared sensitivity determination mechanism determines that the optimal infrared sensor sensitivity is a low sensitivity and an infrared alarm trigger requires high amplitude pulses.

8. The system of claim 6, wherein when the insect range bin detects a target, the infrared sensitivity determination mechanism triggers a time delay, beginning at insect range bin target detection, and terminating at some fixed time after clearance of the insect range bin, wherein infrared signals are ignored during the time delay.

9. The system of claim 4, wherein the short range bins detects crawling intruders under or in the vicinity of the intrusion detector.

10. The system of claim 4, wherein a target within the short range bin and not within the insect range bin triggers an increase in an infrared detector sensitivity level to facilitate detection of crawling intruders.

11. The system of claim 1, wherein a target located within the long range bin and not within the mid range bin, and that transmits a signal having a frequency below a predetermined threshold, triggers an increase in infrared detector sensitivity level in order to detect slow moving intruders.

12. A method for minimizing false alarms due to small animals and insects in a coverage area of a dual detector system, the dual detector system including at least one microwave sensing system and at least one passive infrared sensing system, the method comprising:

determining a target range for a detected target from received microwave signals; and

adjusting a passive infrared sensor threshold based on the determined target range, wherein the passive infrared sensor threshold is at a first level when the detected target is a short range target and second level when the target is a longer range target, such that the first level may be higher or lower than the second level depending on PIR sensitivity in a short range and a long range.

13. The method of claim 12, further comprising dynamically adjusting an infrared sensitivity level to a predetermined threshold upon determination of the target range.

14. The method of claim 13, further comprising determining whether to trigger an alarm based on output from the Microwave sensing system and the passive infrared sensing system.

15. The method of claim 12, wherein determining the target range comprises providing multiple range bins for the microwave sensing system.

16. The method of claim 15, further comprising providing an insect range bin capable of detecting insects in an immediate vicinity of the intrusion detector.

17. The method of claim 16, further comprising adjusting the passive infrared sensitivity to a low sensitivity when the insect range bin detects intrusion, such that an infrared alarm trigger requires high amplitude pulses.

18. The method of claim 16, further comprising, when the insect range bin detects a target, triggering a time delay, beginning at insect range bin target detection, and terminating at some fixed time after clearance of the insect range bin, wherein infrared signals are ignored during the time delay.

19. The method of claim 15, further comprising providing a short range bin for detection of crawling intruders under or in the near vicinity of the intrusion detector.

20. The method of claim 19, further comprising triggering an increase in infrared sensitivity upon detection of a target within the short range bin and not within the insect range bin to facilitate detection of crawling intruders.

21. The method of claim 15, further comprising providing a long range bin such that targets detected within the long range bin and not within the mid range bin, and transmitting a signal having a frequency below a predetermined threshold, trigger an increase in infrared detector sensitivity in order to detect slow moving intruders.

22. A method for improving false alarm immunity for a dual intrusion detector, the dual intrusion detector including at least one microwave sensor and at least one passive infrared sensor, the method comprising:

classifying a received microwave signal into a range bin;

estimating a target range based on a range bin state comparison; and

determining an optimal passive infrared sensor sensitivity level based on the estimated target range.

23. The method of claim 22, further comprising dynamically adjusting a passive infrared sensitivity level to a predetermined threshold upon determination of the target range.

24. The method of claim 22, further comprising determining whether to trigger an alarm based on the state of the microwave sensor and the passive infrared sensor.

25. The method of claim 22, further comprising providing an insect range bin capable of detecting insects in an immediate vicinity of the intrusion detector.

26. The method of claim 25, further comprising adjusting a passive infrared sensitivity level to a low sensitivity level when the insect range bin detects intrusion, such that an infrared alarm trigger requires high amplitude pulses.

27. The method of claim 25, further comprising, when the insect range bin detects a target, triggering a time delay, beginning at insect range bin target detection, and terminating at some fixed time after clearance of the insect range bin, wherein infrared signals are ignored during the time delay.

28. The method of claim 25, further comprising providing a short range bin for detection of crawling intruders under or in the near vicinity of the intrusion detector.

29. The method of claim 28, further comprising triggering an increase in a passive infrared sensitivity level upon detection of a target within the short range bin and not within the insect range bin.

30. The method of claim 22, further comprising providing a long range bin such that targets detected within the long range bin and not within the mid range bin, and transmitting a signal having a frequency below a predetermined threshold, trigger an increase in a passive infrared sensitivity level in order to detect slow moving intruders.