SenTech developed a system consisting of two acoustic arrays with four microphones each in a roughly tetrahedral arrangement. The signal collected by the microphones is processed by a digital signal processor hosted on a fieldable PC to extract the following information:

• The time and direction of arrival of the disturbance generated by the ballistic shock wave. The ballistic shock wave is produced when a bullet flys at supersonic speeds – but not all bullets travel supersonically.
  

Time and direction of arrival of the muzzle blast signature. This signature will unambiguously point in the direction of the shooter.

The signatures are collected simultaneously from two acoustic arrays separated by several hundred feet. The processor solves a complex geometrical problem to determine the direction and range to the source of the shot and displays the result in a map.

SenTech developed the processing algorithms and implemented them for real-time operation using an off the shelf digital signal processor hosted on a portable PC. The system was tested with very positive results at Camp Pendleton’s urban training site (MOUT). This site was a particularly difficult environment because of the severe acoustic multipath. Typically, the system could locate the sniper’s location within one to two degrees in bearing and within 20% in range.

During 2000, SenTech has received additional funding from SPAWAR to improve the operation of the system and its fieldability. This program was supervised by Dr. Ed Carapezza of DARPA and Dr. Dave Law of the US Navy SPAWAR.