System and method for identifying and locating an acoustic event
First Claim
1. A sensor for detecting and providing a time of arrival of an acoustic event produced in the environment comprising:
- a microphone acoustically coupled to the environment, such that said microphone provides a signal representative of acoustic waves received at said sensor;
a microprocessor, said microprocessor being in electrical communication with said microphone such that a digital representation of said signal is present in said microprocessor;
an absolute time clock in digital communication with said microprocessor such that said microprocessor can obtain synchronized time from said absolute time clock;
a network interface in digital communication with said microprocessor such that said microprocessor can communicate over a computer network, wherein when a predetermined event is received at said microphone, said microprocessor obtains a time of arrival from said absolute time clock and transmits said time of arrival over said communication network.
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Accused Products
Abstract
A system and method for detecting, identifying, and fixing the location of the source of an acoustic event. The inventive system includes: a plurality of sensors dispersed at somewhat regular intervals throughout a monitored area; a communication network adapted to deliver information from the sensors to a host processor; and a process within the host processor for determining, from the absolute times of arrival of an event at two or more sensors, a position of the source of the event. Acoustic events are detected and analyzed at each sensor so that the sensor transmits over the network: an identifier for the sensor; an identifier for the type of event; and a precise absolute time of arrival of the event at the sensor. In a preferred embodiment, the system also identifies the type of weapon firing a gunshot.
134 Citations
14 Claims
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1. A sensor for detecting and providing a time of arrival of an acoustic event produced in the environment comprising:
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a microphone acoustically coupled to the environment, such that said microphone provides a signal representative of acoustic waves received at said sensor;
a microprocessor, said microprocessor being in electrical communication with said microphone such that a digital representation of said signal is present in said microprocessor;
an absolute time clock in digital communication with said microprocessor such that said microprocessor can obtain synchronized time from said absolute time clock;
a network interface in digital communication with said microprocessor such that said microprocessor can communicate over a computer network, wherein when a predetermined event is received at said microphone, said microprocessor obtains a time of arrival from said absolute time clock and transmits said time of arrival over said communication network. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for locating and identifying an acoustic event comprising:
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a plurality of sensors for reporting a time of arrival of a known acoustic event, each of said sensors comprising;
a microphone, said microphone producing a signal indicative of acoustic waves received at the sensor;
a microprocessor in communication with said microphone such that information produced by said signal in response to said acoustic waves can be processed by said microprocessor to detect said known acoustic event;
an absolute time clock in digital communication with said microprocessor such that said microprocessor can obtain synchronized time from said absolute time clock; and
a network interface in digital communication with said microprocessor such that said microprocessor can communicate over a network;
a network, each network interface of said plurality of sensors being connected to said network; and
a host processor connected to said network, wherein, upon the occurrence of said known acoustic event, at least one sensor will detect said known acoustic event and, in response to said known acoustic event, report the identity of said acoustic event and the time of arrival of said known acoustic event to said host processor over said network. - View Dependent Claims (11, 12)
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13. A method for locating the source of an acoustic event comprising the steps of:
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providing at least three sensors dispersed over an area to be monitored at known locations, each sensor having a microphone for receiving an acoustic event and a synchronized clock;
providing a network, each of said at least three sensors being configured for communication over said network;
receiving a known acoustic event at said at least three sensors;
at each of said sensors, transmitting a time of arrival of said known acoustic event over said network, said time of arrival being obtained from said synchronized clock;
receiving said time of arrival from each sensor of said at least three sensors at a processor; and
at said processor, triangulating the location of the source of said known acoustic event from said received times of arrival and said known locations.
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14. A method for identifying the source of a known acoustic event comprising the steps of:
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storing envelope and spectral characteristics of a particular acoustic event;
receiving acoustic waves at a sensor;
storing said acoustic waves in memory;
processing the received acoustic waves to derive an envelope of the acoustic waves;
performing a first correlation between points along the derived envelope and points along the stored envelope of said particular acoustic event;
if said first correlation indicates that said derived envelope correlates with the stored envelope of said particular acoustic event, transforming the stored acoustic wave into the frequency domain to create spectral information of said received acoustic wave;
performing a second correlation between said spectral information of said stored acoustic wave and said spectral characteristics of said particular acoustic event; and
if a predetermined number of points of said spectral information correlate with points of said spectral characteristics, providing an identification that said acoustic waves were produced by an event matching said particular acoustic event.
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Specification