(<a href=www.nytimes.com target=_blank>NYT) The system uses four microphones, contained along with the computer in a bulletproof box two feet by two feet by three feet. The system is able to determine quickly where a gun was fired, using the difference in time that the sound took to reach each microphone. The computer sends a signal to the video camera, which zooms in on the location. The system then transmits information and the video directly to law enforcement headquarters. The devices, which cost up to $25,000 each, can cover an area with a radius of about 200 yards. Cmdr. Sid Heal of the Los Angeles County Sheriff's Department, who is in charge of evaluating technology for the agency, said that the system is likely to provide greater "situational awareness." In about six months, the sheriff's department will test the devices, installing as many as 20 around Los Angeles County.