WO2002001528A2 - Method and system for acoustic detection of aerosol dissemination - Google Patents
Method and system for acoustic detection of aerosol dissemination Download PDFInfo
- Publication number
- WO2002001528A2 WO2002001528A2 PCT/US2001/019925 US0119925W WO0201528A2 WO 2002001528 A2 WO2002001528 A2 WO 2002001528A2 US 0119925 W US0119925 W US 0119925W WO 0201528 A2 WO0201528 A2 WO 0201528A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- filter
- electrical signals
- set forth
- activation
- sound
- Prior art date
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Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/16—Actuation by interference with mechanical vibrations in air or other fluid
- G08B13/1654—Actuation by interference with mechanical vibrations in air or other fluid using passive vibration detection systems
- G08B13/1672—Actuation by interference with mechanical vibrations in air or other fluid using passive vibration detection systems using sonic detecting means, e.g. a microphone operating in the audio frequency range
Definitions
- This invention relates generally to a method and system for detecting a potential terrorist attack and, more particularly, to a method for detecting unwanted dissemination of aerosolized agents into an HVAC system of a building or into other environs inhabited by humans.
- CBRN chemical, biological, radiological, or nuclear
- a CBRN agent can be released into the air in a theater or an office building ventilation system discreetly, without an explosion or other warning sign evident to those under attack.
- One known method of releasing a CBRN agent is to utilize an aerosolizer such as those manufactured for the spraying of paint.
- the aerosolizer is placed within or near the HVAC system of a building, the aerosolizer is filled with a bioagent broth or other liquid containing the CBRN agent, and the aerosolizer is either manually activated or programmed to release the agent into the air or into a ventilation system at a predetermined time.
- U.S. Patent No. 5,027,643 describes various detectors for detecting the presence of harmful vapors wherein air samples are collected into a trap before being desorbed into a detector, such as an electron capture detector.
- a detector such as an electron capture detector.
- these detectors are selective in that they only detect certain elements; thus, if the terrorist uses an element that is not detectable by the detector, such detectors are unable to identify the occurrence of an attack.
- many such detectors utilize consumables when they are performing their detection function; thus, it can be costly to use them in a continuous monitoring mode and it would be more cost effective to use them on a selective basis.
- the present invention is a method for detecting unwanted dissemination of aerosolized agents into an HVAC system in a building by detecting the sound of the dissemination at the time it occurs.
- sound extraction techniques e.g., high pass filtering and an adaptive variance estimator, are utilized which can detect the event's noise from within the ambient background noise of the system.
- a microphone or other acoustic sensing device continually monitors background sound levels and senses the additional sound resulting from the activation of the aerosol delivery system, which has a unique sound "signature.” Once an event is detected, defensive actions, e.g., activating additional sensors, closing all air vents, and shutting off the HVAC system, can be taken.
- FIG. 1 illustrates a typical environment in which a CBRN attack could take place and in which the present invention could be utilized to prevent the CBRN attack;
- FIG. 2 is a flowchart illustrating the processing carried out by processing device 124 of Figure 1.
- FIG 1 illustrates a typical environment in which a CBRN attack could take place and in which the present invention could be utilized to prevent the CBRN attack.
- a room to which public access is readily available e.g., a cafeteria 100
- ductwork 102 is a return air vent which draws air in from the cafeteria 100 back into the HVAC system 101.
- Ductwork 106 comprises a standard feeder duct which provides air to the cafeteria 100.
- air is circulated throughout the cafeteria 100 by removing air in direction 104, processing the air through the HVAC system 101, and returning the air so processed back to the cafeteria 100 via ductwork 106 in direction 108.
- a typical CBRN attack could occur as follows.
- An aerosolizer 120 is placed in the vicinity of return 102.
- the user would simply spray the aerosolizer 120 into the return 102, and the HVAC system 101 would draw the spray 121, containing the CBRN agent, into the HVAC system.
- the HVAC system 101 would then process the air (e.g., by cooling or heating the air) and then propel the processed air, carrying the CBRN agent, into the ventilation system for the entire building (including air duct 106).
- the aerosolizer could be placed somewhere inside the ductwork and be activated remotely or based on a timer system so that the CBRN attack would occur when the perpetrator was not in the vicinity.
- the aerosolizer when activated, will release the CBRN agent via a spraying mechanism that will generate a distinctive sound which is different from the overall sound of the HVAC system 101 in operation and the ambient sound in the cafeteria 100.
- an acoustic detector such as a microphone 122, coupled to a processing device, e.g., a computer 124 equipped with a digital signal processor (DSP) and configured for amplifying, recording, storing, and processing sound signals, is situated within the duct 102.
- the microphone/processing device combination is configured in a known manner so as to record sounds on a continuous basis and store the recordings in any known manner, e.g., magnetic tape, sound card, etc.
- the processing device is also configured so as to enable detection of signals that are not generally occurring in the ambient environment, and more specifically, to be able to discriminate between background noise and the sound made by activation of the aerosolizer.
- Many known techniques for detecting specific sounds from within background sounds are well known; see, for example, U.S. Patent No. 3,569,923 to Nau washer et al., incorporated herein fully by reference.
- FIG. 2 is a flowchart illustrating the processing carried out by processing device 124 of Figure 1.
- background noise is filtered out using known arbitrary filtering techniques, e.g., through the use of a high pass filter that will only pass sound signals for sounds which exceed 5 kHz.
- a high pass filter that will only pass sound signals for sounds which exceed 5 kHz.
- the threshold level of the high pass filter can be varied.
- a typical aerosolizer emits a sound bandwidth of approximately 1 to 20 kHz or higher; sounds typical of a "normal living environment" (e.g., an office building or residence) are usually in a bandwidth of approximately 20 Hz- 10 kHz and rarely exceed a frequency of 8 kHz .
- the high pass filtering performed by processing device 124 can be set to a lower level, e.g., 5 kHz. This will pass some of the background noise of the normal living environment, and will pass more of the frequencies generated by the areosolizer.
- the high pass filtering process carried out by processing device 124 can be set closer to the typical sound frequency of an aerosolizer (and farther away from the typical sound frequency of a normal living environment), e.g., above 10 kHz, 15 kHz, 18 kHz, 20 kHz, etc.
- the threshold level can be selected to be any level at or above the lowest level that would enable the sound of the aerosolizer to be distinguished from the background level.
- step 211 if a determination is made that sounds other than the expected background noise are occurring and, more particularly, that those sounds are consistent in character with the sound made by a discharging aerosolizer (e.g., they are sounds at a frequency of 10 kHz or higher), optionally an alarm can be triggered (step 211 A). If no such determination is made, the process can proceed to step 21 IB, where the monitoring continues.
- the processing device 124 can be configured to refrain from issuing an indication of a potential alarm event until the detected aberration can be confirmed as being more than merely a transient occurrence, as described below.
- a potential alarm event for example, in any environment there may be isolated occurrences of high frequency sounds of short duration. An aerosol sprayer being activated for purposes of a terrorist attack would emit this high frequency sound for a sustained period of time, e.g., at least 10 seconds and more likely 30 seconds or more.
- processing device 124 filters out transient event sound measurements using any known selective filtering technique that will achieve this goal, e.g., by the use of a variance estimator.
- variance estimators give less weight to recently occurring detections and more weight to "older" detections, so that only after the occurrence of a noise event above the threshold of the high pass filter and which occurs for a predetermined period of time, e.g., ten seconds or more (more or less, depending upon the desired accuracy), will there be an indication of a confirmation of an alarm event.
- buildings, vehicles, and the like can be monitored, via sound monitoring, for the occurrence of an event bearing the signature of the spraying of an aerosolizer in an environment where such sounds would not otherwise occur.
- CBRN detection devices which detect the presence of harmful vapors and/or materials can be immediately activated, thereby minimizing or eliminating the need to run such devices on a continual basis.
- alarms may be activated to enable the HVAC system to be shut down and to allow building personnel to be evacuated before the harmful effects can be distributed throughout the building.
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Alarm Devices (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001270065A AU2001270065A1 (en) | 2000-06-23 | 2001-06-22 | Method and system for acoustic detection of aerosol dissemination |
EP01948604A EP1295269A2 (en) | 2000-06-23 | 2001-06-22 | Method and system for acoustic detection of aerosol dissemination |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US21364400P | 2000-06-23 | 2000-06-23 | |
US60/213,644 | 2000-06-23 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002001528A2 true WO2002001528A2 (en) | 2002-01-03 |
WO2002001528A3 WO2002001528A3 (en) | 2002-05-16 |
Family
ID=22795915
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/019925 WO2002001528A2 (en) | 2000-06-23 | 2001-06-22 | Method and system for acoustic detection of aerosol dissemination |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1295269A2 (en) |
AU (1) | AU2001270065A1 (en) |
WO (1) | WO2002001528A2 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3569923A (en) * | 1967-10-30 | 1971-03-09 | Us Navy | Adaptive acoustic detector apparatus |
US5027643A (en) * | 1990-03-24 | 1991-07-02 | Ion Track Instruments, Inc. | Method and apparatus for detecting low volatility atmospheric vapors |
-
2001
- 2001-06-22 WO PCT/US2001/019925 patent/WO2002001528A2/en not_active Application Discontinuation
- 2001-06-22 EP EP01948604A patent/EP1295269A2/en not_active Withdrawn
- 2001-06-22 AU AU2001270065A patent/AU2001270065A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3569923A (en) * | 1967-10-30 | 1971-03-09 | Us Navy | Adaptive acoustic detector apparatus |
US5027643A (en) * | 1990-03-24 | 1991-07-02 | Ion Track Instruments, Inc. | Method and apparatus for detecting low volatility atmospheric vapors |
Also Published As
Publication number | Publication date |
---|---|
EP1295269A2 (en) | 2003-03-26 |
AU2001270065A1 (en) | 2002-01-08 |
WO2002001528A3 (en) | 2002-05-16 |
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