And you're right about focusing in where fire is coming from. I remember a special from the Kosovo campaign about our ability to use radar to determine exactly where incoming sniper fire was coming from, and to return fire on that exact path. The Israelis used a similar technology with a .50bmg on a crane during the incident at the Church of the Nativity last year. I can only presume the technology has advanced considerably.
The Los Angeles Sheriff set that system up here in SoCal in Willowbrook in south central L.A. on New Year's eve a few years ago to try and stop some of the shooting at midnight. After several hundred shots the system was too overloaded.
Back to the drawing board.