System and method for precision acoustic event detection

• US 7,751,282 B2
• Filed: 08/30/2008
• Issued: 07/06/2010
• Est. Priority Date: 01/20/2005
• Status: Active Grant

• Current Assignee: Shotspotter Incorporated
• Original Assignee: Shotspotter Incorporated
• Inventors: Fisher, Ken, Holmes, Fred, Baxter, Kevin
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US12/202,268
• Publication Number:
  US 20090109796A1
• Time in Patent Office: 675 Days
• Field of Search: 367/128, 367/906, 342/357.03, 342/357.02, 342/357.06, 342/357.14, 701/207, 701/213, 340/988
• US Class Current: 367/128
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• 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

Abstract

A system and method for providing precision locations for sensors which make up an array of sensors in a gunshot detection system. In a preferred embodiment sensors employ a commercial GPS which reports a sensor position or a group of pseudoranges to GPS satellites. A server collects differential information from a differential node and, in one preferred embodiment, calculates a precision position for each sensor by adjusting the reported position or pseudoranges with the differential information. In another preferred embodiment differential information is sent from the host to individual sensors which calculate their own precision positions. Differential information may be latitude and longitude corrections, pseudorange corrections, ionospheric delay, GPS satellite clock drift, or other corrective term which will improve the accuracy of a sensor position.

Claims

1. A weapon fire detection sensor comprising:

a microphone for receiving an acoustic signal of a weapon fire event;

a first commercial GPS receiver that provides commercial GPS sensor location information regarding the sensor;

a network interface configured to communicate with a host processing unit that is associated with an array of sensors and has a second commercial GPS receiver and a military GPS receiver; and

a processor that;

receives, via the network interface, a precise location of the sensor calculated by the host processing unit as a function of the commercial GPS sensor location information, a commercial GPS signal from the second commercial GPS receiver, and a military GPS signal from the military GPS receiver; and

determines a precise source location of the weapon fire event using the precise location of the sensor, wherein the precise source location of the weapon fire event is more accurate than weapon fire source location information obtained without using the precise location.

2. The sensor of claim 1, wherein time of arrival information from a plurality of microphones arranged in an array is used to determine the precise source location without use of bullet shockwave data.

3. The sensor of claim 2, wherein sensor position is provided using a plurality of pseudoranges.

4. The sensor of claim 1, wherein sensor position is provided using a plurality of pseudoranges.

5. The sensor of claim 1, wherein GPS position information is provided using a plurality of pseudoranges.

6. The sensor of claim 1, wherein calculation of the precise location of the sensor includes adjusting commercial GPS sensor location information with correction information determined by the host processing unit.

7. The sensor of claim 6, wherein sensor position is provided using a plurality of pseudoranges.

8. The sensor of claim 6, wherein GPS position information is provided using a plurality of pseudoranges.

9. A weapon fire detection sensor comprising:

a microphone for receiving an acoustic signal of a weapon fire event;

a first commercial GPS receiver that provides commercial GPS sensor location information regarding the sensor;

a network interface configured to communicate with a host processing unit that is associated with an array of sensors and has a second commercial GPS receiver and a military GPS receiver, wherein the network interface is configured to receive, from the host processing unit, precision position information determined as a function of a commercial GPS signal from the second commercial GPS receiver and a military GPS signal from the military GPS receiver; and

a processor that;

calculates a precise location of the sensor as a function of the commercial GPS sensor location information and the precision position information; and

determines a precise source location of the weapon fire event using the precise location of the sensor, wherein the precise source location of the weapon fire event is more accurate than weapon fire source location information obtained without using the precise location of the sensor.

10. The sensor of claim 9, wherein time of arrival information from a plurality of microphones arranged in an array is used to determine the precise source location without use of bullet shockwave data.

11. The sensor of claim 10, wherein sensor position is provided using a plurality of pseudoranges.

12. The sensor of claim 9, wherein sensor position is provided using a plurality of pseudoranges.

13. The sensor of claim 9, wherein GPS position information is provided using a plurality of pseudoranges.

14. The sensor of claim 9, wherein calculation of the precise location of the sensor includes adjusting commercial GPS sensor location information with correction information determined by the host processing unit.

15. The sensor of claim 14, wherein sensor position is provided using a plurality of pseudoranges.

16. The sensor of claim 14, wherein GPS position information is provided using a plurality of pseudoranges.

17. A computer readable medium containing computer readable instructions executable to perform a method for determining a precise source location of a weapon fire event detected by a weapon fire detection sensor, the method comprising:

processing an acoustic signal of a weapon fire event detected at a microphone in the weapon fire detection sensor;

receiving commercial GPS sensor location information regarding the weapon fire detection sensor from a first commercial GPS receiver;

communicating, via a network interface, with a host processing unit that is associated with an array of sensors and has a second commercial GPS receiver and a military GPS receiver;

processing precision position information, from the host processing unit, that is determined as a function of a commercial GPS signal from the second commercial GPS receiver and a military GPS signal from the military GPS receiver;

calculating a precise location of the sensor as a function of the commercial GPS sensor location information and the precision position information; and

determining a precise source location of the weapon fire event using the precise location of the sensor, wherein the precise source location of the weapon fire event is more accurate than weapon fire source location information obtained without using the precise location of the sensor.

18. The computer readable medium of claim 17 wherein time of arrival information from a plurality of microphones arranged in an array is used to determine the precise source location without use of bullet shockwave data.

19. The computer readable medium of claim 17, wherein sensor position is provided using a plurality of pseudoranges.

20. The computer readable medium of claim 17, wherein GPS position information is provided using a plurality of pseudoranges.

21. The computer readable medium of claim 17, wherein calculation of the precise location of the sensor includes adjusting commercial GPS sensor location information with correction information determined by the host processing unit.