Calif. city to test system that pinpoints gunshots

November 09, 1994|By Knight-Ridder News Service

REDWOOD CITY, Calif. -- If you fire a gun in east Redwood City next year, the police will know about it almost the moment you pull the trigger.

City Council members voted unanimously Monday night to spend $25,000 on the nation's first field test of an urban gunshot location system, a high-tech web of microphones and data lines that can pinpoint the source of a gunshot within a few feet.

Although a $5.5 million federal grant was approved last month to install a citywide system in Washington, D.C., Redwood City will become the first community to try a high-tech solution to the random gunfire that has terrified its eastern neighborhoods.

If successful, the system eventually will be able to tell police dispatch computers about gunfire within 4 seconds of an initial shot.

Plans call for the system to indicate with a circle on a detailed map in the police dispatch center where the shots were fired.

Researchers say initial tests at a desert site often were accurate within 10 feet; occasionally the system pinpointed the location within a yard.

Rattled residents, who have complained about both celebratory gunfire and occasional gunbattles in the streets, cheered the decision.

Child in bathtub

"You can't understand what it's like until you've experienced diving [for safety] with a child in hand," said Maria Diaz, who said she placed her infant daughter in a cast-iron bathtub to protect her from bullets during a early-morning street fight last year.

Residents of east Redwood City have been lobbying the city for nearly a year to spend more than $250,000 on a fully functional gunshot location system.

But council members, stuck trying to decide between hiring more police officers and giving them this new tool, decided first to find out whether such a system would actually work.

No city in the world yet has a fully functioning urban gunfire location system.

Although details of the test system still must be worked out, researchers said it most likely will cover roughly a one-square-mile area of both Redwood City and unincorporated San Mateo County.

On light posts

Four to six small units containing sound sensors and data relay lines will be installed on top of light posts and buildings, where they will be tuned to listen for gunfire 24 hours a day.

Using seismic technology that pinpoints the epicenter and strength of earthquakes, scientists from SRI International of Menlo Park will use a computer to time when the sound of a shot arrives at three or more of the sensor locations.

Using the millisecond differences in arrival times, the computer then can calculate through a process called triangulation exactly where the sound originated.

Redwood City officials decided to let SRI conduct the test, although they also received a bid from a new company created by Robert Showen, the former SRI engineer who spearheaded the Menlo Park company's gunshot location project until he was laid off last spring.

Firecrackers, backfires

Researchers said they are still perfecting technology that differentiates between the sound of a gunshot, a firecracker and a car backfiring.

But the current technology being tested between the buildings at SRI's Menlo Park campus has been effective, said John Ciboci, the project manager.

If the cost of conducting a thorough test in Redwood City exceeds $25,000, Councilman Jack Greenalch said, county Supervisor Ruben Barrales has promised to try to persuade the county to contribute as much as $25,000 more.

SRI also has asked the state attorney general to grant as much as $125,000 to expand the system.

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