A ShotSpotter network includes 12 to 20 sensors per square mile. Roughly the size of a medium pizza, the devices are hidden on rooftops, utility poles, and in other inconspicuous places. Here are the components of a typical unit:
Microphone An internal microphone array gives the sensor 360-degree coverage and makes it possible to determine the direction a sound came from.
GPS Receiver Global positioning satellites give the location of each sensor. GPS also serves as a central clock, making it possible to triangulate an incident's location based on the speed of sound.
Thermometer Air temperature determines the speed of sound — crucial to calculating a shot's location. The server at the station checks the Net for other atmospheric conditions that affect sound waves.
Network Connection Each sensor is in constant contact with the server. Some are connected by a telephone line. Others have a digital link managed by a microprocessor.
Memory In sensor units with a processor, if communication is interrupted or bandwidth becomes clogged, the memory stores the sounds until they can be uploaded.
Shot Spotter
Spotting the Shot
