Alarm system for detecting an audio signal when glass breakage occurs

• US 5,414,409 A
• Filed: 07/23/1992
• Issued: 05/09/1995
• Est. Priority Date: 07/23/1992
• Status: Expired due to Fees

• Current Assignee: International Electronics Incorporated (Melrose Industries Plc)
• Original Assignee: International Electronics Incorporated (Melrose Industries Plc)
• Inventors: Voosen, Robert C., Hentschel, Christopher
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US07/919,031
• Time in Patent Office: 1,020 Days
• Field of Search: 340/550, 340/566, 340/541, 340/663, 340/521, 340/691, 340/514, 340/506, 340/636
• US Class Current: 340/541
• CPC Class Codes: G08B 13/04 by breaking of glass
• CPC Class Codes: G08B 13/1672 using sonic detecting means, e.g. a microphone operating in the audio frequency range

Abstract

A processor, such as a microprocessor, responds to the detection of an input audio signal generated by glass breakage to cause an alarm to be indicated, such as at a remotely located alarm control panel. The system determines when the input power supply voltage supplied to the system falls below a selected low voltage level. The system is placed in a test mode of operation in response to a uniquely characterized, humanly generated input sound signal and then can be tested by any appropriate humanly generated input sound signal. The system continually monitors ambient background noise and determines when an absence thereof occurs so as to provide an indication of such absence to alert the user to the possibility that the system may have been purposely comprised. The system further uses a number of indicators arranged so that the meanings thereof are different depending on whether the system is in an alarm detection mode of operation or in a test mode of operation. Finally, the system operates in conjunction with a different intrusion event detection device so that, if a glass breakage signal is detected by the system, the detection of an intrusion event by the other device is monitored so as to confirm that a true intrusion has occurred before an alarm is indicated.

Claims

1. An alarm detection system for detecting the presence of an audio signal when glass breakage occurs, said system comprising

amplifier means responsive to an input audio signal for providing an amplified audio output signal;

filter means responsive to said audio output signal for providing one or more filtered audio signals;

processing means responsive to said one or more filtered audio signals for determining when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

means responsive to said determination for providing an alarm signal when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

means for supplying a power supply voltage for use in said alarm detection system;

means for monitoring the level of said power supply voltage; and

means responsive to said monitoring means for determining when the level of said power supply voltage is below a selected level;

said processing means being responsive to said determining means for providing an indicator signal when said power supply voltage level is below the selected level; and

visual indicator means which is turned off when said power supply voltage level is above the selected level and which is responsive to said indicator signal for turning on said indicator means when said power supply voltage is below the selected level to provide a visual indication of a false alarm condition.

2. An alarm detection system in accordance with claim 1, wherein said indicator signal is a pulsating signal and said visual indicator means is a light indicator which flashes on and off when said visual indicator means is turned on in response to said pulsating signal.

3. An alarm detection system for detecting the presence of an audio signal when glass breakage occurs, said system comprising

amplifier responsive to an input audio signal for providing an amplified audio output signal;

filter means responsive to said audio output signal for providing one or more filtered audio signals;

processing means responsive to said one or more filtered audio signals for determining when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

means responsive to said determination for providing an alarm signal when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

said amplifier means being further responsive to a uniquely characterized humanly generated input audio signal; and

said processing means being responsive to filtered audio signals which result from said uniquely characterized input audio signal for placing said alarm system in a test mode of operations.

4. An alarm detection system in accordance with claim 3 wherein said processing means responds to first and second filtered audio signals which result from said uniquely characterized humanly generated input audio signal to start first and second timers having specified time durations;

said processing means determining whether said first and second filtered audio signals are still present when said first and second timers expire at the end of said specified time durations; and

said processing means incrementing a counter means when said first and second filtered audio signals are not present at the end of said specified time durations.

5. An alarm detection system in accordance with claim 4 wherein said processing means places said alarm system in a test mode of operation when the count of said counter means reaches a selected count number.

6. An alarm detection system in accordance with claim 4 wherein said uniquely characterized input audio signal comprises a selected number of humanly generated, relatively short bursts of audio sound in relatively rapid succession and said alarm system is placed in a test mode of operation when the count of said counter means reaches a count of equal to said selected number.

7. An alarm detection system in accordance with claim 6 wherein said selected number of relatively short bursts of audio sound are produced by humanly generated hand claps.

8. An alarm detection system in accordance with claim 3 wherein, when said alarm system is placed in a test mode of operation,

said amplifier means responds to a humanly generated test input audio signal;

said processing means responds to at least one filtered audio output which results from said test input audio signal and turns on at least one indicator means to signify a successful testing of said system.

9. An alarm detection system in accordance with claim 8 wherein said test input audio signal is a humanly generated audio sound having either high frequency or low frequency components, or both.

10. An alarm detection system in accordance with claim 3 and further including test timing means for automatically placing said system back into its alarm detection mode of operation after a selected time duration of said test timing means.

11. An alarm detection system in accordance with claim 3 wherein said alarm system is normally in an alarm detection mode of operation when it is not placed in said test mode of operation, and further including a plurality of indicator means, the operating status of each of which has a first meaning when said alarm system is in said alarm detection mode of operation and a second meaning when said alarm system is placed in a test mode of operation.

12. An alarm detection system in accordance with claim 11 wherein said plurality of indicator means includes a selected number of visual indicators.

13. An alarm detection system in accordance with claim 12 wherein said visual indicators are light emitting devices.

14. An alarm detection system in accordance with claim 12 wherein said filter means includes a high frequency filter and a low frequency filter and said plurality of visual indicators indicate an alarm status, a power on status and a background noise presence status when in said alarm detection mode of operation and wherein at least two of said visual indicators indicate the presence of filtered audio signals at the outputs of said high frequency and low frequency filters when in said test mode of operation.

15. An alarm detection system for detecting the presence of an audio signal when glass breakage occurs, said system comprising

amplifier means responsive to an input audio signal for providing an amplified audio output signal;

filter means responsive to said audio output signal for providing one or more filtered audio signals;

processing means responsive to said one or more filtered audio signals for determining when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

means responsive to said determination for providing an alarm signal when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

said amplifier means being further responsive to ambient input audio background noise signals having an amplitude above a selected level, said noise signals being generated in an environment in which said alarm system is placed; and

said processing means responding to said ambient input audio background noise signals for turning on an indicator means when said ambient input audio noise signals are not present.

16. An alarm detection system in accordance with claim 15 wherein said processing means responds to said ambient input audio background noise signals and sets a timer means having a selected time duration when said an input audio noise signals are present;

and

said processing means re-sets said timer means for said selected time duration when said input audio background noise signals are present before the end of said selected time duration, said timer means continuing to be re-set before the end of each selected time duration if said input audio background noise signals are present.

17. An alarm detection system in accordance with claim 16 wherein said processing means responds to said ambient input audio background noise signals so as to turn on an indicator means if said input audio background noise signals have not been present during the time duration of said timer means to signify the absence of said ambient input audio background noise signals.

18. An alarm detection system in accordance with claim 17 wherein said processing means responds to the filtered audio signals from said filter means which result from said ambient background input audio background noise signals.

19. An alarm detection system in accordance with claim 18 wherein said filter means includes a high frequency filter and a low frequency filter and said processing means responds to the presence of output signals from both said high frequency and low frequency filters due to the presence of said input audio background noise signals to set and re-set said timer means.

20. An alarm detection system for detecting the presence of an audio signal when glass breakage occurs, said system comprising

amplifier means responsive to an input audio signal for providing an amplified audio output signal;

filter means responsive to said audio output signal for providing one or more filtered audio signals;

a single processor responsive to said one or more filtered audio signals for providing a first alarm indication for a selected time period when said filtered audio signals represent an audio input signal that has been generated due to glass breakage;

means for monitoring the output of a second alarm system which detects the occurrence of a different intrusion event and provides a monitored signal when said different intrusion event accompanies the occurrence of a glass breakage event;

said single processor detecting the presence of said monitored signal and providing a second confirmatory alarm indication different from said first alarm indication only when said monitored signal has been detected during said selected time period.

21. An alarm detection system in accordance with claim 20 wherein said first alarm indication is a light signal of a first color and said second confirmatory alarm indication is a light signal of a second color.