Gunfire locator

A gunfire locator or gunshot detection system is a system that detects and conveys the location of gunfire or other weapon fire using acoustic, optical, or potentially other types of sensors, as well as a combination of such sensors. These systems are used by law enforcement, security, military and businesses to identify the source and, in some cases, the direction of gunfire and/or the type of weapon fired. Most systems possess three main components:

Systems used in urban settings integrate a geographic information system so the display includes a map and address location of each incident.

Determination of the origin of gunfire by sound was conceived before World War I where it was first used operationally.

In the early 1990s, the areas of East Palo Alto and eastern Menlo Park, California, were besieged with crime. During 1992 there were 42 homicides in East Palo Alto, making it the per capita murder capital of the United States. The Menlo Park police department was often called upon to investigate when residents reported gunshots; however there was no way to determine their source from scattered 911 calls.

In late 1992 John C. Lahr, a PhD seismologist at the nearby United States Geological Survey, approached the Menlo Park police department to ask if they would be interested in applying seismological techniques to locate gunshots. Others had also approached the Menlo Park police department suggesting ways to help the police by means of gunshot location systems. The police chief arranged a meeting with local inventors and entrepreneurs who had expressed an interest in the problem. At that time there were no solutions to tracking gunshots, only a desire to do so. One key attendee was Robert Showen, a Stanford Research Institute employee and expert in acoustics.

Lahr decided to go ahead with his plans to demonstrate the feasibility of locating the gunshots, relying on his background in the earthquake location techniques and monitoring in Alaska. A network consisting of one wired and four radio-telemetered microphones was established, with his home in eastern Menlo Park becoming the command center. Lahr modified the software typically used for locating earthquakes and recorded the data at a higher sample rate than is used for regional seismology. After gunshots were heard, Lahr would determine their location while his wife monitored the police radio for independent confirmation of their source.

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