Method for acoustically counting gunshots fired indoors

Patent metadata

Field	Value
Publication number	US-11604050-B2
Application number	US-201716328093-A
Country	US
Kind code	B2
Filing date	Aug 15, 2017
Priority date	Aug 29, 2016
Publication date	Mar 14, 2023
Grant date	Mar 14, 2023

Abstract

After determining that a gunshot has been fired, particularly indoors, the method of the invention is employed to determining the number of gunshots fired by analyzing consecutive windows of time over a certain time period. That is, after it is determined that a gun has been fired, the method is employed to identify that the gun is an automatic or rapid fire weapon by quickly counting the number of rounds shot over short periods of time. This information can be used to provide shooting details, both in connection with notifying emergency personnel and enabling the personnel to assess details of the shooting incident.

First claim

The invention claimed is:

1. A method of acoustically counting a number of fired gunshots comprising the steps of:
a) determining a RMS value of signals from a microphone over a predetermined time period;
b) averaging multiple RMS values together to establish an average RMS value;
c) calculate a slope of consecutive RMS values; and
d) determining a shot count based on results of steps a)-c).

2. The method of claim 1 , wherein step b) constitutes averaging three RMS values together.

3. The method of claim 1 , further comprising: after performing step c), determining if 3 or more consecutive slope values are greater than zero before moving to step d).

4. The method of claim 1 , further comprising: determining if a maximum RMS value is greater than a predetermined value before moving to step d).

5. The method of claim 4 , wherein the predetermined value is 400.

6. The method of claim 4 , further comprising: if the slope in step c) drops negative, restart the count.

7. The method of claim 1 , further comprising:
after performing step c), determining if 3 or more consecutive slope values are greater than zero or determining if a maximum RMS value is greater than a predetermined value, before moving to step d).

8. The method of claim 1 , further comprising: continuing the method until the RMS value drops below 5000.

9. The method of claim 1 , further comprising: if the average RMS value drops below ⅓ of the average RMS value, pause a predetermined time period and then proceed back to step a).

10. The method of claim 9 , wherein the predetermined time period is 10 ms.

11. The method of claim 1 , further comprising: outputting a shot count indicating the number of fired gunshots.

12. The method of claim 1 , further comprising: alerting emergency personnel of the number of fired gunshots.

13. The method of claim 1 , wherein the method is performed in acoustically counting the number of fired gunshots within a building.

14. The method of claim 1 , wherein the microphone has a low sensitivity.

15. A method of acoustically counting a number of fired gunshots comprising:
a) determining RMS values of signals from a microphone over a predetermined time period;
b) averaging multiple RMS values together to establish average RMS values;
c) calculating slope values of consecutive RMS values;
d) determining an existence of a gunshot within the predetermined time period when 3 or more consecutive slope values are greater than zero; and
e) determining a shot count based on results of steps a)-c) repeated for subsequent time intervals until the entire window has been analyzed.

16. The method of claim 15 , wherein step b) constitutes averaging three RMS values together.

17. The method of claim 16 , wherein the predetermined value is 400.

18. The method of claim 15 further comprising:
determining if a maximum RMS value is greater than a predetermined value in step d).

19. The method of claim 15 , further comprising: if the slope in step c) drops negative, restart the count.

20. The method of claim 15 , further comprising: if the average RMS value drops below ⅓ of the average RMS value, pause a wait time period and then proceed back to step a).

21. A method of acoustically counting a number of fired gunshots comprising:
a gunshot counting process executing on a processor of a gunshot detection sensor mounted within a structure to be monitored for gunshots performing steps a) through f) as follows, wherein the gunshot detection sensor comprises a computer board linked to a microphone and connected to the processor, which is an electrically powered multi-core processor capable of sampling acoustic signals received from the microphone at a minimum of 192 kHz:
a) determining RMS values of signals from the microphone over a predetermined time period, wherein the microphone is a MEMS microphone having a sensitivity below −40 dBFS;
b) averaging multiple RMS values together to establish average RMS values;
c) calculating slope values of consecutive RMS values;
d) determining an existence of a gunshot within the predetermined time period when 3 or more consecutive slope values are greater than zero;
e) determining a shot count based on results of steps a)-c) repeated for subsequent time intervals until an entire window has been analyzed; and
f) outputting the shot count indicating the number of fired gunshots and/or alerting emergency personnel of the shot count.

Assignees

• Tyco Fire & Security Gmbh

Inventors

• Pirkle Wesley C
• Shoaf Richard L

Classifications

• F41J5/06 Primary

  Acoustic hit-indicating systems, i.e. detecting of shock waves (F41J5/056 takes precedence) · CPC title

• G08B13/1672

  using sonic detecting means, e.g. a microphone operating in the audio frequency range · CPC title

• F41A19/01

  Counting means indicating the number of shots fired · CPC title