The Shotspotter Gunshot Location System was developed by Dr. Robert Showen and is marketed by Trilon Technology, a technology company located in Mountain View, California. According to press releases and newspaper articles, Shotspotter is currently deployed in 32 jurisdictions nationwide.
Shotspotter GLS works through strategic placement of acoustic sensors at various locations such as on rooftops and telephone poles in areas where gunfire is a problem. Trilon says that as few as eight sensors are needed to cover up to one square mile of a city. The sensors are housed in weatherproof casings about 15” x 4” x 4”.
When suspected gunfire is detected, Shotspotter determines the location through triangulation by using the time it takes for the sound waves to reach each sensor. The data are transmitted to a central station at police headquarters and through the use of a global positioning system; a graphic of the event is displayed on a map of the protected area. The time from the first discharge of a weapon to registration at the central station is reportedly within 15 seconds and has been shown to be accurate to within 25 meters.
This technology is similar to that used to pinpoint the epicenter of an earthquake. Shotspotter can also be used in conjunction with video surveillance and facial recognition software.
The sounds of the suspected gunfire are recorded for forensic analysis at a later time or the event immediate playback is required to determine if the sensor may have been tripped by some loud noise other than a gunshot. The manufacturer is confident that properly calibrated sensors will not generate false positive indicators nor eavesdrop on conversations held in a normal tone of voice. The Shotspotter triangulation method appears below: