History
Determination of the origin of gunfire by sound was conceived prior to 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 related to drug traffic. 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 U.S. Geological Survey, approached the Menlo Park police department to ask if they would be interested in applying seismological techniques to locate gun shots. 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 point 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 1 wired and 4 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. Using this system, Lahr was able to demonstrate to the police and others that this technique was highly effective, as the system was able to locate gunshots occurring within the array to within a few 10's of meters. Although additional techniques from the seismic world were known that could better automate the system and increase its reliability, those improvements were outside the scope of this feasibility study.
Read more about this topic: Gunfire Locator
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