Apparatus and method for calibrating an acoustic detection system

• US 7,830,750 B2
• Filed: 09/17/2007
• Issued: 11/09/2010
• Est. Priority Date: 09/17/2007
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Smith, Richard A.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Ratcliffe; Luke D
• Application Number:
  US11/856,235
• Publication Number:
  US 20090073803A1
• Time in Patent Office: 1,149 Days
• Field of Search: 367 87-191
• US Class Current: 367/128
• CPC Class Codes: G08B 13/04 by breaking of glass
• CPC Class Codes: G08B 13/1663 using seismic sensing means
• CPC Class Codes: G08B 13/1672 using sonic detecting means, e.g. a microphone operating in the audio frequency range
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence
• CPC Class Codes: G08B 29/22 Provisions facilitating manual calibration, e.g. input or output provisions for testing; Holding of intermittent values to permit measurement

Abstract

A system and method for calibrating an acoustic detector. The method includes the steps of simultaneously transmitting an acoustic signal and an electromagnetic signal to an acoustic detector, receiving both signals, calculating a timing difference between the reception of the acoustic signal and electromagnetic signal, and setting a first time threshold used to determine if a glass panel is broken using the calculated difference and storing the first time threshold. A sensitivity level is also set based upon the determined timing difference. A unique key signature in the acoustic signal and electromagnetic signal is detected and matched with a stored signature to determine whether the signals are from a calibration signal. The timing difference is only calculated if both signals are calibration signals.

Claims

1. A method of calibrating an acoustic detector comprising the steps of:

encoding a unique key signature in an acoustic signal and an electromagnetic signal, the unique key signature identifies a calibration device;

transmitting simultaneously the acoustic signal and the electromagnetic signal from the calibration device;

receiving the electromagnetic signal at an acoustic detector;

receiving the acoustic signal at the acoustic detector;

detecting the unique key signature in the acoustic signal and in the electromagnetic signal for determining whether the signals are calibration signals;

if the signals are calibration signals, then calculating a timing difference between the reception of the acoustic signal and electromagnetic signal; and

storing the calculated timing difference as a first time threshold for determining if a glass panel is broken.

2. The method of calibrating an acoustic detector according to claim 1, further comprising the steps of:

adding a preset tolerance value to the calculated timing difference; and

storing a result of the addition as a second time threshold.

3. The method of calibrating an acoustic detector according to claim 1, further comprising the steps of:

converting the calculated timing difference into a distance vector; and

setting a detection threshold for a sensing element that corresponds to said distance vector.

4. The method of calibrating an acoustic detector according to claim 3, further comprising the steps of:

adding a tolerance distance to the distance vector to generate an adjusted distance vector; and

reading out the detection threshold from a table that corresponds to said adjusted distance vector.

5. The method of calibrating an acoustic detector according to claim 1, wherein said electromagnetic signal is a visible light signal.

6. The method of calibrating an acoustic detector according to claim 1, wherein said electromagnetic signal is an RF signal.

7. The method of calibrating an acoustic detector according to claim 1, wherein said electromagnetic signal is an infrared signal.

8. A calibration device for calibrating an acoustic detection system comprising:

a. an acoustic signal generating section for generating an acoustic signal having a unique signature corresponding to the calibration device;

b. a speaker for transmitting said acoustic signal to an acoustic detector;

c. a signal generating section for generating an electromagnetic signal having a second unique signature corresponding to the calibration device; and

d. a transmitter for simultaneously transmitting the electromagnetic signal to the acoustic detector.

9. The calibration device according to claim 8, further comprising a user interface section for receiving a user input, said user input initiating the calibration of the acoustic detection system.

10. The calibration device according to claim 9, further comprising a control section for controlling the acoustic signal generating section, the speaker, the signal generating section and transmitter based upon the user input, said control section causing the speaker and transmitter to simultaneously transmit the acoustic signal and the electromagnetic signal to the acoustic detector.

11. The calibration device according to claim 10, wherein said control section includes;

a processor for controlling functionality of the calibration device;

a memory for storing the unique signature and digitized pulses of the acoustic signal; and

a clock for maintaining an internal timing, said clock allowing the control section to cause the speaker and transmitter to simultaneously transmit the acoustic signal and the electromagnetic signal to the acoustic detector.

12. The calibration device according to claim 8, wherein said transmitter is a light emitting diode.

13. The calibration device according to claim 8, wherein said acoustic detection system includes an acoustic detector and an impact sensor.

14. An acoustic detector comprising:

a sensor for detecting an acoustic signal;

a receiver for detecting an electromagnetic signal;

a comparison section for detecting a unique signature in the acoustic signal for determining whether the acoustic signal is a calibration signal;

a timer for recording a reception time of the electromagnetic signal and a reception time of the acoustic signal if the acoustic signal is a calibration signal;

a calculating section for determining a timing difference between the reception times of the electromagnetic signal and the acoustic signal if the acoustic signal is a calibration signal; and

a controller for storing the timing difference as a first time threshold if the acoustic signal is a calibration signal for determining if a glass panel is broken.

15. The acoustic detector according to claim 14, wherein the timer records the reception time upon receipt of a leading edge of the electromagnetic signal and a leading edge of a first pulse in the acoustic signal.

16. The acoustic detector according to claim 15, wherein said controller converts said time differences into a distance vector.

17. The acoustic detector according to claim 16, wherein said controller sets a detection threshold based upon said distance vector.

18. A system for calibrating an acoustic detector comprising:

an impact sensor for transmitting a signal to an acoustic detector; and

a calibration device for encoding an acoustic signal with a unique signature that identifies that calibration device and simultaneously emitting the acoustic signal to the acoustic detector,

wherein said acoustic detector determines a time of reception of the signal and the acoustic signal, determines if the acoustic signal includes the unique signature, and, if so, calculates a difference in the reception time of the signal and the acoustic signal and sets the difference as a first time threshold for determining if a glass panel is broken.

19. The system for calibrating an acoustic detector according to claim 18, wherein said acoustic detector determines a distance from a window to the acoustic detector based upon the difference and sets a sensitivity level for the acoustic detector based upon the distance.