System and method for archiving data from a sensor array

• US 20070230270A1
• Filed: 12/23/2005
• Published: 10/04/2007
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: Shotspotter Incorporated
• Original Assignee: Shotspotter Incorporated
• Inventors: Calhoun, Robert
• Granted Patent: US 7,411,865 B2
• Time in Patent Office: Days
• US Class Current: 367/117
• CPC Class Codes: G01S 5/22 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations

Abstract

A system and method for archiving and retrieving information from an array of remote sensors. In a preferred embodiment the invention is incorporated in a gunshot detection and location system to preserve audio information surrounding a gunshot event for later review or analysis. In a preferred embodiment the system includes a plurality of acoustic sensors deployed in an array, a computer for processing gunshot information from the sensors, and a mass storage device for temporary archival of audio information. When a gunshot event is detected, the location of the audio information of the data within the spool is stored in an index to facilitate later retrieval of the information.

Claims

1. An improved gunshot detection system of the type having an array of acoustic sensors placed over an area to detect gunshots and to provide a source location of a received gunshot, wherein each sensor provides an audio signal which is sampled at periodic intervals, the improvement comprising a mass storage device, wherein the samples of the audio signals are stored in said mass storage device such that the audio signal from each sensor may be reproduced and the relative timing between audio signals from different sensors of said array of sensors is accurate during the reproduction.

2. The improved gunshot detection system of claim 1 wherein said mass storage device includes a file structure and a plurality of files such that an absolute time is associated with each file of said plurality of files and the samples of the audio signals sampled at said absolute time are stored in a file associated with said absolute time.

3. The improved gunshot detection system of claim 2 wherein said plurality of files includes a file associated with each second of a predetermined period of time.

4. The improved gunshot detection system of claim 3 wherein said file structure further includes a plurality of minute directories, each minute directory being associated with a minute of said predetermined period of time and wherein said each minute directory contains sixty files associated with the seconds of the minute.

5. The improved gunshot detection system of claim 4 wherein the file structure further includes a plurality of hour directories, each hour directory being associated with an hour of said predetermined period of time and wherein said each hour directory contains sixty minute directories associated with the minutes of the hour.

6. The improved gunshot detection system of claim 5 wherein the file structure further includes a plurality of day directories, each day directory being associated with a day of said predetermined period of time and wherein said each day directory contains 24 hour directories associated with the hours of the day.

7. The improved gunshot detection system of claim 6 wherein said predetermined period of time is 3 days.

8. The improved gunshot detection system of claim 2 wherein each file is further associated with a particular sensor of said array of sensors such that each sensor of said array of sensors has an associated file which is further associated with an absolute time.

9. The improved gunshot detection system of claim 1 wherein said mass storage device comprises a recirculating buffer wherein a first sample of the audio signal is stored for a predetermined period of time and upon expiration of said predetermined period of time said first sample is replaced with a second sample of the audio signal.

10. The improved gunshot detection system of claim 2 wherein said samples are compressed when stored in said each file.

11. The improved gunshot detection system of claim 1 wherein when a gunshot event is detected, an index to said gunshot event is stored on said mass storage device to facilitate the later reproduction of said sampled audio signal surrounding said gunshot event.

12. The improved gunshot detection system of claim 11 wherein when a non-gunshot event is detected, an index to said non-gunshot event is stored on said mass storage device to facilitate later reproduction of said sampled audio signal surrounding said non-gunshot event.

13. The improved gunshot detection system of claim 12 wherein determination of a source location of said gunshot event is performed from said later reproduction.

14. The improved gunshot detection system of claim 11 wherein a permanent recording is made of said later reproduction.

15. A method for archiving audio information in a gunshot detection system of the type having an array of acoustic sensors placed over a geographic area, wherein said array of sensors detects gunshots which occur proximate the array, the method comprising the steps of:

(a) providing a mass storage device;

(b) periodically sampling an audio signal from each sensor; and

(c) storing each sample in said mass storage device wherein the audio signal from each sensor can be reproduced with the relative timing between the audio signals of each sensor preserved.

16. The method for archiving audio information of claim 15 wherein step (a) includes the substeps of:

(a)(i) providing a mass storage device; and

(a)(ii) providing a file structure on said mass storage device, said file structure having a plurality of files, each file having an absolute time associated therewith;

17. The method for archiving audio information of claim 16 wherein in step (c) each sample is stored in a file having an appropriate absolute time associated therewith.

18. The method for archiving audio information of claim 17 wherein each file of said plurality of files represents one second of sampled audio.

19. The method for archiving audio information of claim 18 wherein said files representing one second of sampled audio are organized into minute directories, each minute directory having sixty said files representing one second of sampled audio.

20. The method for archiving audio information of claim 15 further including the step of:

(d) when a gunshot is detected, storing an index to the location of the stored samples in said mass storage device corresponding to said gunshot.

21. The method for archiving audio information of claim 20 further including the step of:

(e) reproducing the audio surrounding said gunshot by using said index to locate said stored samples corresponding to said gunshot.