Automatic real-time gunshot locator and display system
First Claim
1. A system for locating a loud explosive event such as gunfire within a region containing explosive events and other weaker impulsive sounds, the system comprising:
- a collection of acoustic sensors for detecting acoustic signals, wherein the acoustic sensors have distinct sensor locations within the region, and wherein the average nearest neighbor separation between the sensors is at least 1000 ft., thereby providing spatial filtering of the acoustic signals detected by the sensors; and
a signal processor in communication with the collection of acoustic sensors, wherein the signal processor performs the following steps;
(a) examining the acoustic signals to identify first, second, and third acoustic signals from distinct acoustic sensors, wherein each of the identified acoustic signals has an energy abruptly and significantly rising above an average value of the acoustic signal;
(b) calculating a location in the region by comparing the identified first, second, and third acoustic signals;
whereby intrinsically weak acoustic signals are discriminated against by the large separation between the sensors, thereby improving the performance of the system.
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Accused Products
Abstract
A system to accurately and rapidly present the location of gunfire or other explosive events to dispatchers uses a sparse set of distributed acoustic sensors mounted on rooftops or utility poles to allow triangulation of the gunfire sounds. If a fourth signal confirms that an explosive event occurs at a position triangulated from three other signal, then the system announces an event to dispatchers. The system tests various sensor triads against various criteria and selects the best triad for making the triangulation calculation. In the case where multiple gunshots are present, the system can automatically determine a velocity, thus helping identify and respond to drive-by shootings. The system presents a confirmed location on a computer map of the protected community showing where on a specific property the gunfire occurred. The dispatchers can listen to the event and can view wave forms or spectra to assist in discriminating gunshots from other explosive events. If a dispatcher is confident that a gunshot has been detected, law enforcement officers can be directed to the reported location. A printout of the event is generated so police can later show the event location to the residents and inquire why it occurred there. A history of events is maintained for community problem-solving.
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Citations
21 Claims
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1. A system for locating a loud explosive event such as gunfire within a region containing explosive events and other weaker impulsive sounds, the system comprising:
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a collection of acoustic sensors for detecting acoustic signals, wherein the acoustic sensors have distinct sensor locations within the region, and wherein the average nearest neighbor separation between the sensors is at least 1000 ft., thereby providing spatial filtering of the acoustic signals detected by the sensors; and a signal processor in communication with the collection of acoustic sensors, wherein the signal processor performs the following steps; (a) examining the acoustic signals to identify first, second, and third acoustic signals from distinct acoustic sensors, wherein each of the identified acoustic signals has an energy abruptly and significantly rising above an average value of the acoustic signal; (b) calculating a location in the region by comparing the identified first, second, and third acoustic signals; whereby intrinsically weak acoustic signals are discriminated against by the large separation between the sensors, thereby improving the performance of the system. - View Dependent Claims (2, 3, 4)
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5. In a system comprising a collection of acoustic sensors in communication with a signal processor, a method for locating a strong explosive event in a region containing explosive and impulsive sounds, the method comprising the steps of:
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identifying from among acoustic signals detected by the acoustic sensors a first signal from a first sensor, wherein the first signal exceeds an average noise level by a significant factor; if a first sharpness value of the first signal exceeds an initial sharpness threshold, then identifying from among the acoustic signals a second signal from a second sensor and a third signal from a third sensor, wherein the first, second, and third sensors are distinct from each other, and wherein the first sharpness value measures a degree to which an energy of the first signal abruptly and significantly rises above an average value; and if a second sharpness value of the second signal and a third sharpness value of the third signal both exceed a triangulation threshold that is less than the initial sharpness threshold, then calculating from the first, second, and third signals a location. - View Dependent Claims (6)
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7. A system for locating an explosive event within a region, the system comprising:
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a collection of acoustic sensors for detecting acoustic signals, wherein the acoustic sensors are positioned at separate sensor locations within the region; and a signal processor in communication with the collection of acoustic sensors for locating the explosive event from the acoustic signals; wherein the signal processor performs the following steps; (a) examining the acoustic signals to identify first, second, and third sharp acoustic signals from distinct acoustic sensors, wherein the identified sharp acoustic signals have energies that rise abruptly and significantly above average values of the signals; (b) calculating a candidate location in the region by comparing the identified first, second, and third sharp acoustic signals; (c) examining the acoustic signals to identify a fourth sharp acoustic signal; and (d) if the fourth sharp acoustic signal was identified in (c) and satisfies a criterion that confirms the calculated candidate location, then reporting the candidate location. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for detecting and locating an explosive event within a region, the system comprising:
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a collection of acoustic sensors for detecting acoustic signals, wherein the acoustic sensors are positioned at separate sensor locations within the region; and a signal processor in communication with the collection of acoustic sensors for identifying and locating the explosive event from the acoustic signals; wherein the signal processor is programmed in accordance with the following steps; (a) examining the acoustic signals to identify a first set of three sharp acoustic signals from distinct acoustic sensors, wherein the first set of three sharp acoustic signals correspond to a first candidate gunshot event and have energies that rise abruptly and significantly above average values of the first set of signals; (b) calculating a first candidate location in the region by comparing the identified first set of three sharp acoustic signals with each other; (c) examining the acoustic signals to identify a second set of three sharp acoustic signals from distinct acoustic sensors, wherein the second set of three sharp acoustic signals correspond to a second candidate gunshot event and have energies that rise abruptly and significantly above average values of the second set of signals; (d) calculating a second candidate location in the region by comparing the identified second set of three sharp acoustic signals with each other, and calculating a difference between the first and second candidate locations; and (e) if the difference between the first candidate location and the second candidate location is less than a predetermined threshold, then reporting a confirmed explosive event. - View Dependent Claims (20)
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21. A system for detecting and locating an explosive event within a region, the system comprising:
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a collection of acoustic sensors for detecting acoustic signals, wherein the acoustic sensors are positioned at separate sensor locations within the region; and a signal processor in communication with the collection of acoustic sensors for locating the explosive event from the acoustic signals; wherein the signal processor performs the following steps; (a) examining the acoustic signals to identify a set of triads, wherein each triad comprises three sharp acoustic signals from distinct acoustic sensors; (b) identifying for each triad a number of confirming signals from other acoustic sensors; (c) selecting a best triad from the set of triads, wherein the best triad has a largest number of confirming signals; (d) calculating a location in the region by comparing the three sharp acoustic signals of the best triad; and (e) reporting the calculated location.
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Specification