System and method for detecting and analyzing near range weapon fire

Abstract

A method for identifying a gunshot occurrence. According to one embodiment, microphone data and inertial motion data are acquired with a hand-held device. Based on an acoustic criterion, a determination is made as to whether a gunshot has been produced. Based on a correlation criterion applied to the inertial motion data, a determination is made as to whether the gunshot was produced from fire produced by a first person having physical possession of the hand-held device or by a second person spaced away from the first person.

Claims

1. A computer-implemented method for monitoring whether a person in possession of a first hand-held communications device is in the presence of weapon fire, comprising: receiving, into a non-transitory computer readable storage medium, via a wireless network, information derived from measured acoustic data acquired with a microphone connected to the first hand-held device; and processing the information to determine, based on whether a sound pressure level in the acoustic data exceeds a predetermined level, whether an acoustic event is the result of weapon fire within ten meters of the hand-held device.

2. The computer-implemented method of claim 1 wherein the information received into the non-transitory computer readable storage medium is information received into a computer system via the network and which indicates whether acoustic data processed in the hand-held device meets threshold correlation conditions used to determine that the acoustic event is the result of weapon fire.

3. The method of claim 2 further including receiving into the computer system, from one or more additional hand-held communications devices, additional information confirming occurrence of the acoustic event.

4. The method of claim 1 wherein the information received into the non-transitory computer readable storage medium is information received into a computer system via the network, the method further including: receiving into the computer system from other hand-held communications devices additional information confirming occurrence of the acoustic event; and providing results of additional analysis indicating whether the acoustic event resulted from weapon fire.

5. The method of claim 4 wherein the results of additional analysis are obtained based on analysis, performed on the computer system, of the additional information received from the other hand-held devices.

6. The method of claim 1, wherein the information received into the non-transitory computer readable storage medium is information received into a computer system via the network, and wherein the person is a law enforcement official in a group comprising one or more additional law enforcement personnel each in possession of one of the additional hand-held devices, and the additional information is sent to the computer system from at least one of the additional law enforcement personnel, the method further including: sending a notification from the computer system to at least one device associated with one of the additional law enforcement personnel for display thereon that an event of weapon fire has been detected at a location where the first hand-held communication device has been present.

7. A method of determining whether an officer present during a weapon fire incident is out of ammunition or how much ammunition is left, by counting the number of firings, comprising: acquiring microphone data during weapon firings with a hand-held communication device having a wireless network connection; acquiring inertial data during the weapon firings with the hand-held communication device; storing the microphone data and the inertial data in a non-transitory computer readable storage medium; using a microprocessor to determine from the inertial data whether each in a plurality of gunshots has been produced from fire produced by a first person in possession of the hand-held device or by one or more other persons spaced away from the hand-held device; and counting the number of weapon firings produced by the first person.

8. A method of identifying a gunshot occurrence with a hand-held communication device, comprising: performing automatic microphone recording of data with a hand-held communication device upon detection of a signal having a predetermined sound level; performing analysis of the data with a processor running on the hand-held device to determine whether the signal having the predetermined sound level has been produced from gun fire; and providing information based on whether the signal having the predetermined sound level has been produced from gun fire to a computer system via a wireless network.

9. The method of claim 8 wherein determination of gunfire is made by correlating the acoustic signal with a time varying function characteristic of gun fire.

10. The method of claim 9 wherein determination of gunfire includes a determination of whether the detected sound level has been produced by a person holding the hand-held device or by another person.

11. A method of detecting weapon fire with a hand-held device of the type having a microphone capable of detecting acoustic energy present at the hand-held device, the hand-held device including capability of recording acoustic energy detected by the microphone, the hand-held device having one or more second sensors for detecting inertial movement of the hand-held device, the hand-held device including capability of recording data associated with detected inertial movement, comprising: using the microphone to continually generate a first time series of acoustic voltage signals indicative of temporally varying sound pressure levels at the hand-held device; using the second sensors to continually generate a second time series of voltage signals indicative of temporally varying inertial movement of the hand-held device; analyzing signals in the first series to identify an event for which voltage for the sound pressure level exceeds a predetermined threshold value; determining a first set of correlations between signals in the first series and information characteristic of gunfire, wherein a threshold correlation value is associated with each correlation in the first set; determining a second set of correlations between signals in the first set and signals in the second set wherein a threshold correlation value is associated with each correlation in the second set; when at least one of the correlations of the first set exceeds the associated threshold correlation value, sending information from the hand-held device via the network indicating there has been an occurrence of gun fire; and when at least one of the correlations of the second set exceeds the associated threshold correlation value, sending information via the network that a weapon which created the occurrence of gun fire has been fired by a person having possession of the hand-held device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout, and wherein:

(2) FIG. 1 illustrates select features of a command center network which supports gunshot detection in a law enforcement operation;

(3) FIG. 2A illustrates a secure login process in one of a plurality of mobile client devices to initiate a subroutine for monitoring sound and detecting a gun fire incident;

(4) FIG. 2B illustrates a sound monitoring subroutine which runs on a client device to continually control measurement of sound levels, analyze and report out information;

(5) FIG. 2C illustrates timer function subroutine used to periodically acquire the physical location information and provide updated reports to a server regarding weapon fire;

(6) FIG. 2D illustrates a subroutine in which a client device initiates data requests and receives data from a server;

(7) FIG. 3A illustrates a subroutine implemented on a server for receiving and disseminating information concerning a potential or determined weapon fire event; and

(8) FIG. 3B illustrates a subroutine implemented on a server in which the server receives and responds to a request from one of multiple client devices for a most current list of nearby officers and associated graphic display data.

(9) In accord with common practice, the various described features are not drawn to scale, but are drawn to emphasize specific features relevant to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(10) The described examples illustrate numerous features according to embodiments of the invention, but the invention is not so limited. Methods and systems are provided for identification of gun firing incidents using hand held devices such as mobile telephones as audio receivers. The devices are capable of automatically generating and sending alerts to personnel at command centers and other locations to generate rapid responses and coordinate responses among personnel located at multiple locations. Because gun shots may be the second most common cause of mortality in law enforcement operations, embodiments of the invention are described which can be readily deployed in state and local law enforcement organizations. For example, embodiments enable determinations as to whether a gunshot is the result of firing a weapon by an officer or has been produced by firing of a weapon by someone other than the officer. It is also useful to determine with reliability the number of rounds of ammunition fired from the officer's weapon. This information contributes to improved situational awareness and can lead to indications such as whether the officer is about to run out of ammunition or needs to reload a weapon. Automated alerts can provide other officers and the command center with location information for the incident based on data communicated from the same hand-held device which automatically generates the alert. Information concerning the gun fire incident can be displayed in the form of a critical alert, in conjunction with location information on maps which are displayable on like hand-held devices in the possession of multiple law enforcement personnel. The law enforcement operation may automatically receive a recording of all events occurring shortly after the gunfire, such as may be automatically made by the same hand-held device which generates the alert. The recording may, for example, be used in a post incident review of the situation as objective evidence, analogous to utilizing information recorded in a “black box” after an aircraft incident.

(11) FIG. 1 illustrates select features of a command center network 4 which supports gunshot detection in a law enforcement operation 6 which can be used to improve situational awareness of deployed personnel according to the invention. In this example, the deployed personnel may be officers on patrol in a police department. The operation includes a command center 8 connected to a server 10. The command center 8 comprises an operator console 12 at which is located a computer 14 or at a network terminal which includes conventional human machine interfaces, e.g., a keyboard 16, a mouse 18 and a monitor display 20. The server 10 and the computer 14 are part of the command center network 4, having connectivity between the server 10, the computer 14 or network terminal and numerous other communications devices, including hand held devices 24 (e.g., mobile telephones or tablet computers) in the possession of officers on patrol, and notebook computers 26 mounted in patrol vehicles 28 assigned to officers on duty. The server is a computer system comprising a processor, memory and storage media. As further described herein, the storage media contains a database which is accessed and modified with an application running on the server to perform analyses and to store and update information.

(12) As shown for the embodiment of FIG. 1, the operation 6 has multiple assets deployed outside the command center to perform typical field activities of a local police department. Physical assets include an array of hand-held devices, which for the illustrated embodiments are the mobile telephones 24, each assigned to an officer on duty, and multiple patrol cars 28 in which the notebook computers are mounted. More generally, the hand-held devices may be processor based communications devices, including devices commonly referred to as tablet PCs or tablet computers, capable of data communications with a server via a WiFi link or a cellular data link. For the disclosed embodiments the mobile telephones 24 or other hand-held devices operate on a common cellular network with conventional rf links 28 to commercial cell towers and base stations. Voice communications capability is desirable but not required on the hand-held devices. It is noted that other embodiments contemplate personnel having both a telephone 24 for voice communications and a second hand-held device capable of wireless data communication for identifying and sending alerts regarding gun fire events.

(13) An icon 30, illustrated as a tower in FIG. 1, is representative of a complete cellular network, comprising a plurality of towers and base stations through which communications are exchanged among the plurality of mobile telephones 24 and with personnel at the command center 8. Communications are exchanged between individual telephones 24 and the server 10 through the cellular network 30. To effect these communications the server 10 has a network connection 32 through which communications are sent or received via the base stations and towers. The network connection 32 also effects communications between the computer 14 at the command center 8 and the server 10 which may be remote from the computer 14. For example, the server 10 may operate at a location distant from the physical assets belonging to the law enforcement operation 6 and be made available by an independent provider of services to the law enforcement operation 6 on a shared basis with other clients, e.g., other law enforcement operations. In other embodiments, the server 10 may be an asset internal to the law enforcement operation 6 and connected to the computer 14 on an internal network.

(14) The command center 8 and the officers performing field activities (e.g., patrolling or responding to emergency calls) may rely upon multiple modes of communication to coordinate activities and information. Possible modes include conventional police band radios, the mobile telephones 24 and, for officers assigned to patrol cars 28, notebook computers 26 mounted in the patrol cars 28. In the illustrated embodiment, the notebook computers 26 are each connected to the server 10 via a wireless communications link 34 to the base stations and towers of the cellular network 30. The wireless links 34 may be provided with conventional wireless modem cards 36.

(15) Generally, it is desirable to provide methods which utilize these existing law enforcement resources to improve the situational awareness of the officers performing the field activities. To this end, the mobile telephones 24 are client devices with respect to the server 10, each running applications which communicate with the other to support detection and analysis of gun firings and promulgation of alerts when such weapon fire has occurred in close range (e.g., within five meters) of one of the telephones 24. The telephones 24 each run a Gun Shot Detection application 40 and the server 10 runs a Gun Shot Alert application 42. The applications 40 each include a communications interface for transferring information to one another.

(16) In the following examples client devices, e.g., the telephones 24, running the Gun Shot Detection application 40, are each enabled to automatically provide event information to the server 10. As one example, the client device may provide information to, or may request information from, the server by generating a Java request object. When sending event information, such as correlation results or recorded audio information, the client device adds the information to the object, serializes the request object (i.e., the request object undergoes Java object serialization) and sends it to the server. Upon receipt, the server deserializes the data and stores the information in a database 38. The server 10 then sends an empty Java response object to the client device. Upon receipt of the response object the client device closes the HTTP connection with the server.

(17) As is common for many mobile telephones, client devices used according to the invention may include multiple microphones, e.g., often three microphones. By simultaneously receiving audio signals through several microphones, it is possible to discriminate a signal from background noise by performing noise cancellation. A first microphone through which a user speaks to communicate is positioned to receive relatively strong speech signals which are typically encoded and transmitted for voice communications. On the other hand, background noise may be received at approximately the same level by the first microphone as well as a second or even a third microphone connected to the mobile telephone 24. Audio processing performed prior to encoding can improve the signal-to-noise ratio of the speech signals by subtracting the background noise, present in signals generated by the second or third microphone, from the acoustic voltage signals generated by the first microphone.

(18) Advantageous features of embodiments of the invention are based, in part, on recognition that acoustic energy associated with a gunshot, which might otherwise be treated as background noise, are not be removed by processing methods applied to improve the quality of a voice signal in a hand-held device. When acquiring microphone data using circuitry of the telephone 24 to detect weapon fire, noise reduction circuitry can be disabled so that the audio signal being analyzed to detect the gunfire includes most or all audio information found in unprocessed data. This is desirable, whether the audio data to be analyzed is received from one microphone or multiple microphones of the hand-held device, to provide a more realistic depiction of the acoustic events analyzed to detect weapon fire. For these reasons, especially when the telephone includes multiple microphones, the application 40 initially modifies default settings on the telephone to prevent subtraction of background noise. However, disabling noise reduction circuitry or other forms of filtering normally used for the purpose of reducing noise during voice communication—in order to better capture features of an acoustic signal, does not preclude later use of filtering or other processing techniques to analyze a signal or prior to performing correlations.

(19) The subroutines shown in FIGS. 2 and 3 illustrate functionality while actual implementations will vary. Examples assume multiple officers are simultaneously logged into hand-held client devices, e.g., telephones 24, and the applications 40 are continuously running on the client devices possessed by each officer while the application 42 is running on the server 10. With reference to FIG. 2A, a process for monitoring sound and detecting a gun fire incident is initiated in each mobile client device with an officer performing a secure login process as summarized in subroutine 210. Each officer uses an assigned client device (e.g., a telephone 24 or other hand-held device) to simultaneously log into both the client device and the server 10 via the network 4 to access the applications 40 and 42.

(20) Once the officer is logged into the network server 10, multiple client functions are initiated on the client device in cooperation or coordination with functions running in the server application 42. Subroutines shown in FIGS. 2 and 3 are exemplary of functionality implemented by the applications 40 and 42.

(21) Client subroutine 220 of the application 40, shown in FIG. 2B, is a sound monitoring application which runs on the client device to continually measure sound levels received with one or more microphones on, for example, the telephone 24. The subroutine 220 of controls, analyzes and reports out to the server 10 results from ongoing collection of acoustic data during periods when the telephone 24 is not engaged in voice communications. To detect an acoustic signal which may result from a gun fire event, acoustic data is acquired with one or more microphones of the telephone 24 after the settings on the telephone 24 are altered so that the microphone data can be processed without first subtracting out background noise. However, if a call is initiated or received on the telephone 24 while the application 40 is running, the telephone processor may automatically suspend acquisition of acoustic data until the call is terminated or, in some embodiments, monitoring can continue while a call is in process. During periods when the call is in process, the telephone reverts to settings which subtract background noise to enhance the quality of voice communications during the call. When the call in process is terminated, the application again automatically alters the settings so that background noise is no longer subtracted from microphone data and ongoing analysis of acoustic data resumes.

(22) Accordingly, after the hand-held settings are altered to process microphone data without subtracting background noise, the application 40 controls circuitry in the telephone 24 to enable operation of the microphones and generate voltage signals indicative of the acoustic signals present at the telephone during time periods when the phone is not engaged in voice communications. Data received from one or more of the microphones are processed to determine, based on correlations, whether a gunfire event has occurred and whether the event was caused by the person in possession of the mobile telephone 24, e.g., a law enforcement officer. To this end, the acoustic voltage signals are compared to a reference value to determine if, at any time, the sound pressure level (spl) of the acoustic signal exceeds a predetermined threshold level, A. The threshold level, A, may be a threshold loudness level, e.g., in the range of 90-130 dB, which would normally be present when a gunshot is fired within about five meters from the telephone 24. The value of the reference voltage level is scaled to correspond to the loudness level, A.

(23) As long as the spl remains below the threshold level A, the Subroutine 220 continues to serially process the microphone data, comparing the acquired levels of the acoustic voltage signal to the reference level to determine whether an event has occurred. When the level of the acoustic voltage signal exceeds the threshold level A, it is assumed that an event has occurred which may be a gun shot and the subroutine begins recording the acoustic voltage signals on a storage medium for analysis. In one embodiment, the acoustic voltage signals as continuously received from the microphone(s) are initially stored in a circular buffer (i.e., a memory which continuously receives data, overwriting the oldest data with new data) which is periodically overwritten. When criteria are met to initiate recording on the storage medium, data existing in the buffer (i.e., a series of measured acoustic voltage values acquired prior to the time when the event occurred) are transferred to the storage medium. The buffer contains adequate memory space to accommodate storage of data corresponding to a period, occurring prior to the detection, of sufficient length to capture useful information for analysis and determination of event attributes. With use of the buffer memory a relatively small amount of data can be temporarily stored corresponding, for example, to less than 0.5 sec of recordable sound. This assures preservation of limited acoustic information during a period preceding detection of the threshold level. Thus with use of a circular buffer a limited amount of data can be captured before occurrence of an event so that analysis and correlation of recorded sound is not only based on portions of a signal corresponding to decay of an impulsive signal. The data in the circular buffer can be transferred to the storage medium when additional data are to be recorded or, in the absence of an event, can simply be overwritten with new microphone data.

(24) The beginning time of the recording written to the storage medium may be based on the portions of temporal data used in correlation analyses to draw inferences about the event. Generally, the acoustic voltage signals are recorded in memory or storage media of the telephone 24 at least during a period of time suitable for performing correlation analyses which confirm whether a gun shot has been fired, and which are determinative whether the gun shot was fired by the person possessing the telephone 24. Highest levels of confidence in determinations may be had by constructing recording periods which begin at times prior to occurrence of the acoustic event and extend through and after occurrence of the event. On the other hand, considerations of available buffer capacity and conservation of battery power may necessitate that recordings only include data obtained after the event is detected. The total recording time for such an acoustic event may exceed three to five seconds per event in order, for example, to capture repeated gun fire without experiencing a discontinuity in the recording.

(25) According to an embodiment of the invention, inertial motion is monitored to facilitate determination of whether a gun shot event has occurred and whether the gun shot was fired by the person possessing the hand-held device. During at least a portion of the period in which the acoustic voltage signals are recorded, the hand-held device also records inertial motion data, e.g., as may be acquired with accelerometers based on movement of the hand-held device. The period during which inertial motion data is acquired may be coincident with the period of recording of the acoustic voltage signals in order to optimally perform time series correlation analyses. If the acoustic recording includes microphone data acquired prior to detecting a voltage level exceeding the threshold value A (e.g., either by continuous recording of microphone data into storage or with use of a circular buffer), accelerometer data may also be so acquired, e.g., stored in a circular buffer for possible later analysis. That is, the telephone may include sufficient buffer memory to acquire and preserve accelerometer data which was generated prior to and at the time the level of acoustic voltage signal was found to exceed the threshold level A. Accordingly, accelerometer data may be preserved simultaneously with acoustic data to perform correlations which result in reliable determinations as to (i) whether the event was a gun shot and (ii) whether a gun shot was fired by the person having possession of the telephone or other hand-held device at the time of the event. Decisions of when and how to record the data can influence reliability of determinations made, for example, based on correlations. There may be trade-offs between confidence levels and power consumption. Although correlation analyses may be preferred methods of making determinations, other methods may be utilized which detect known characteristics of gunshot events, or which screen events by a process of elimination. For example, if a signal is found to exceed the threshold level, A, but contains periodic information uncharacteristic of weapon fire, the event may still be reported to the application 42 running on the server, but identified as not being the result of weapon fire. Also, if the event is accompanied by accelerometer data uncharacteristic of weapon fire (e.g., if the acoustic signal is preceded by a large amplitude ground vibration signal) the event may still be reported but identified as not being the result of weapon fire.

(26) When the law enforcement organization provides multiple officers with hand-held communications devices programmed to monitor gun fire, several of the devices may be used to detect and report distant gun fire, e.g., gun fire which is relatively distant from one hand-held device which has identified and reported a signal exceeding the threshold level, A. The distant gun fire may be identified based on a combination of (i) analysis of measured microphone voltage levels which do not exceed the threshold value A, and (ii) correlation or other detection techniques which reliably determine that such events are likely to be weapon fire. The application 40 can automatically report events of distant gun fire to the server 10 for use in further analysis to improve the confidence level of results reported by the one hand-held device which detected the weapon fire at a close distance (i.e., for which measured microphone voltage levels exceeded the threshold value A). If the hand-held device stores microphone data for limited periods (e.g., up to thirty seconds) the server can send requests out for potential gun shot information occurring in that limited period. The server may provide a desk officer in the law enforcement operation with a list identifying by name the nearby officers in possession of the hand-held devices which have reported the distant gunfire temporally coincident with detection of weapon fire at a close distance from the one hand-held device which has reported a signal exceeding the threshold level, A. The desk officer may then dispatch the nearby officers to the location of the event.

(27) FIG. 3A illustrates a process implemented on the server 10 by the application 42 for receiving and disseminating information concerning a potential or determined weapon fire event. The server application 42 receives a Client Request Object from a first hand-held communication device which detects an acoustic event in order to (i) provide notification to the server 10 that a determination based on established criteria has been made, indicating that a detected acoustic event was the result of weapon fire, or (ii) provide information, e.g., correlation data, which can be compared to criteria present in the data base 38 of the server, to make a determination of whether the acoustic event resulted from a weapon fire. Similarly, the server application 42 may receive from the same or a different Client Request Object from the first hand-held device (i) a notification that the weapon fire event was caused by a person in possession of the first hand-held communication device, or (ii) information, e.g., correlation data, which the application 42 can compare to criteria present in the data base 38 in order for the server to make a determination of whether the weapon fire event was caused by the person in possession of the first hand-held communication device.

(28) Once the computer system receives, via the cellular network connection, digital information, providing an indication of whether the measured acoustic data resulted from weapon fire, the server may also receive from one or more additional hand-held communications devices additional information confirming occurrence of the acoustic event. The server may then perform additional analysis to provide results which may further indicate whether or not the acoustic event resulted from weapon fire, or to confirm location of the weapon fire. Based on the information received and any analysis performed by the server, the server sends notification of information concerning the determined gun fire event to multiple hand-held devices.

(29) With reference to FIG. 2C the client subroutine 230 utilizes a timer function (i) to periodically acquire the physical location of the officer based on, for example, GPS data acquired by the client device, and (ii) to periodically provide updated reports to the server regarding weapon fire. For example, with the counter set to a start value determinative of a predefined time interval (e.g., five to sixty seconds) updates to the location of the officer are periodically written to memory or storage in the client device. Also, on each occasion the counter value reaches zero, periodically updated information stored in the client device is available for access in order to routinely send current available information regarding weapon fire and officer location to the server.

(30) At least whenever a gunshot event is detected, the client subroutine 230 sends updates to the server 10 regarding the officer location and other status information of the officer in possession of the device which detects the gunshot event. That is, request objects can be automatically and periodically populated based on most recent updates to information stored in the client device. Alternately, each time the timer value is decremented to zero, the client device may send the officer location and link status to the server 10. The received information is used as an update to the officer's status and location information stored in the server data base 38. Each update may provide the same status information as an immediately preceding update or may provide changes to the status information.

(31) In the foregoing example, the client device provides updated information to the server. This may be effected with a component software module of the client application 40, referred to as the Adjacent Officer Manager Service, running in the background of the client device. The Adjacent Officer Manager Service periodically sends to the server, or acquires from the server, updates of information. When providing information to the server, such as an update to the officer's current location, the client device generates a Java request object, adds the current officer location information to the object, serializes the request object (i.e., the request object undergoes Java object serialization) and sends it to the server. Upon receipt, the server deserializes the data and updates the data base 38 accordingly. The server then sends an empty Java response object to the client device. Upon receipt of the response object the client device closes the HTTP connection with the server.

(32) The Adjacent Officer Manager Service periodically requests updates for a list of nearby officer information for display on the client device. The requested updates are based on information periodically received by the server from each officer logged into the server application 42. In order for the client device to obtain a list of nearby officers from the server, the client device generates a Java request object (i.e., that the server provide the list), serializes it and sends it to the server. Upon receipt, the server deserializes the request object and queries the database to identify nearby officers (according to specified criteria such as distance from the client device making the request). The server then builds a Java response object, populates it with location data and information relating to weapon fire, serializes it and sends the response object to the client device which generated the request object. The client device deserializes the response object, closes the HTTP connection and processes the list of officers, e.g., to generate and display a list or a map of officer locations.

(33) The client subroutine 240 of FIG. 2D illustrates a generic process in which the client device initiates data requests and receives data from the server. The request object is serialized, e.g., undergoes Java object serialization, and is assembled in memory as a data sequence or is stored as a file descriptive of the object and object type. Object serialization converts the message request so that it can be transmitted through an open network socket created by the client device and across the network 10 to the server 12 for receipt in the application 34. See, also, FIG. 3B in which the server subroutine 320 receives and responds to a request from one of multiple client devices for a most current list of nearby officers and associated graphic display data. When the mobile client devices request updated lists of nearby officers from the server, the information is used to update maps on the mobile devices, displayed lists of officers, and other components of the server application 42 which utilize this information. This allows the mobile client devices to display timely information relevant to weapon fire, including officer locations. Any client screens that display a list or map of other officers can be updated to display such officers in an identifiable way.

(34) Multiple embodiments of methods for detecting near range weapon fire have been described. By near range it is meant that the source of the weapon fire may be positioned within ten to forty meters of a hand-held device when the weapon firing is detected. In some embodiments the distance between the hand-held device and the weapon may be five meters or less, but it is possible for the method to provide reliable detections when the distance is much greater, e.g., substantially more than forty meters.

(35) Although the invention has been described with reference to specific embodiments, the invention is not limited to these examples but, rather, is only limited by the scope of the claims which follow.