Word: signallers
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...antinoise collide, they interact with what is called destructive interference, canceling each other out. The idea is not new; generations of high-school physics students have seen destructive interference demonstrated with undulating Slinkies or jump ropes. But it is only recently -- with the advent of small, high-speed signal processors -- that scientists have had the computer power to make practical antinoise devices...
...analog approach, first developed in the 1930s using vacuum-tube technology, works something like a seesaw. A mechanism drives a loud speaker that pushes the air when incoming sound waves rise and pulls it back when the sound waves fall. Alternatively, antinoise waves can be created digitally, using a signal processor to convert incoming sound waves into a stream of numbers. Given those numbers, computers can quickly calculate the frequency and amplitude of the mirror-image waves. Those specifications are then fed to a conventional speaker and broadcast into the air. Sounds that the system wants to preserve, like human...
...zones of silence. Soon, lawn mowers and snow-blowers may be electronically muzzled to reduce suburban din. And, thanks to antinoise systems, submarines carrying nuclear warheads now run silent as well as deep. "Everywhere you hear noise, there's a business opportunity," says Gene Frantz, applications manager for digital signal processing at Texas Instruments. "We're at a stage of the technology where the first guy to the problem can be rich...
...scene began with five seconds left to play in the first period and Colgate defenseman Allan Brown serving time for a holding infraction. The teams were lining for a face-off to the right of the Red Raider goalie Dave Gagnon when Ciavaglia gave the signal...
...KRON, the NBC affiliate in San Francisco, tried to transmit its footage of the disaster to NBC via satellite. But for more than an hour after the tremor, a glitch-prone NBC network was unable to broadcast any live reports. Meanwhile, CNN, which had access to the same satellite signal, was airing KRON's vivid images of the destruction...