The ShotSpotter GLS uses a network of weatherproof acoustic sensors to record and locate gunshots and other loud noises. When a gun is fired, spherical sound waves radiate up to 2 miles. The sensors detect the sound and identify it as a possible gunshot. The recording is transmitted to a server at police headquarters, along with the direction from which the sound came, the time it was detected, the sensor's location, and the current temperature. When at least three sensors have detected the sound, the server triangulates the exact location based on time-of-arrival reading from the sensors. SECURES is another acoustic gunshot detection system. Its battery-operated sensors can distinguish gunshots from other sounds, including engine backfires and fireworks. Sensors are generally located at every intersection and can be mounted on utility poles, street lights, and buildings. Detection information is wirelessly transmitted to a receiving station, which tags the time and data. Once several sensors have relayed the information, the differences in arrival time are used to triangulate the location of the gunshot. A third gunshot location system called SENTRI uses Dynamic Synapse Neural Network technology, which is based on neurobiological principles of brain signal processing. Similar to the human brain, it can accurately perform pattern recognition of acoustic signals. Once the sound of a gunshot has been recognized, standard triangulation methods pinpoint its source. SENTRI sensors operate as individual recognizers that can be mounted on poles, fences, or buildings. The units communicate wirelessly to a central command center, with the option to send alert data and video to laptops in police vehicles.