Shotspotter hits more than it misses

There are lots of reasons for cities not to buy into the ShotSpotter system.

It’s not cheap. It’s not that easy to use. It can end up wasting valuable police resources if misused.

But the big reason to get on board — like San Francisco, Oakland, Richmond, East Palo Alto, and a couple of others — is that it flat out works, and can help police get help to shooting victims, and in some cases help locate and prosecute the shooter.

The ShotSpotter system is fairly a simple concept: A network of audio sensors installed on utility poles and buildings detects and locates gunfire within a community.

For shots fired outdoors, it’s accurate to about five yards, sensitive enough to detect if multiple gunshots were fired from a moving car.

The cost is steep: $200,000 – $300,000 per square mile installed, or about 20 percent of that cost annually if installed purely on a subscription basis.

Training and experience is required for officers and support staff to analyze the audio waveforms and tell the difference between actual gunfire and false alarms like fireworks, machinery, and backfiring cars.

Mountain View’s SST, the maker of the ShotSpotter, knows that false alarms can be a problem. They now offer cities a central screening service that — for a fee — helps filter out false alarms with about a 20-second wait time between shot and verification.

Richmond used the system to detect 218 gunfire events in November. More than 600 false alarm sounds were detected and discarded by the system and operators.

East Palo Alto demonstrated their ShotSpotter system to reporters Thursday, and said the system will be watched closely throughout the New Year’s weekend.