The AP reports on NYPD preparations for the Republican convention

At the Brooklyn training site on Thursday, police practiced disarming a truck bomb at a checkpoint. Scores of officers also made mock arrests of police academy cadets who posed as protesters.

Chanting “no justice, no peace,” the cadets surrounded a bus full of “delegates” before officers in riot gear raced in, slapped on plastic “flex cuffs” and led them away to vans.

The demonstration was intended to show how the nation’s largest police department hopes “to put a comprehensive security net over Madison Square Garden and the rest of the city,” said Police Commissioner Raymond Kelly.

The NYPD plans to unveil its two recently-purchased Long Range Acoustic Devices, crowd-control devices which will be mounted on humvees to issue orders (or any other sound, for that matter) at 150 decibels.

The military, which has used the machines in Iraq, bills them as a “non-lethal weapon” designed to disperse hostile crowds or ward off potential foreign combatants by delivering prerecorded warnings in several languages and, if needed, an earsplitting screeching noise. But police insist the latter feature won’t be used at the convention.

“It’s only to communicate in large crowds,” Inspector Thomas Graham of the department’s crowd control unit said Thursday.

Graham said police had tried out the device in Times Square, and found it delivered clear, even sound over four blocks. Decibel readers will be used to keep the volume at a safe level, he added.

Still, Bill Dobbs of United for Peace and Justice, which has planned a massive anti-war demonstration on the eve of the convention, called the sound system “a potential Big Brother nightmare.”

Police “are trying to use technology and machinery to control every aspect of life on the street, rather than relax a little and let a part of democratic society unfold,” he said.

Other devices in the arsenal being tested includes motor scooters, hand-held radiation detectors, and mechanical barriers strong enough to stop moving vehicles.