199 lines
10 KiB
Plaintext
199 lines
10 KiB
Plaintext
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(word processor parameters LM=8, RM=75, TM=2, BM=2)
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Taken from KeelyNet BBS (214) 324-3501
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Sponsored by Vangard Sciences
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PO BOX 1031
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Mesquite, TX 75150
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There are ABSOLUTELY NO RESTRICTIONS
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on duplicating, publishing or distributing the
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files on KeelyNet except where noted!
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February 26, 1993
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NOISECNC.ASC
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This file is from the Dallas Morning News of
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Saturday, February 13, 1993 - Business section.
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The following file is most intriguing and applies to one of the root
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studies of Vangard Sciences and KeelyNet. Keely used compound
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vibrations and we believe at various phasing differentials. This
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phase adjustment is known in modern terms as interference or phase
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conjugation and can be either constructive (additive) or
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destructive. Use of such principles can lead to phenomena beyond
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simple cancellation of a signal, but we will stay within the context
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of the article as given.
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Technology Report
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Silence is gold for companies
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Experiments seek noise reduction
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by Rebecca Smith
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San Jose, Calif. - Imagine summer without the earsplitting roar of
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power lawn mowers, flying without hearing the whining din of jet
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engines, running the dishwasher without having to shout over the
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noise.
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Companies that make noisy products are looking at an ingenious
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breakthrough technology that enables them to dramatically reduce
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unwanted sounds.
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"Active noise reduction" systems represent the broadest assault on
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noise pollution since invention of the muffler. Products employing
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the technology will begin showing up in mass consumer products later
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this year.
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In what could be a boost for U.S. competitiveness, about 75 patents
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covering product-specific applications of the technology are
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controlled by two U.S. companies.
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"It'll be part of the next wave of luxury home appliances and cars,"
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says technology analyst Dan Hutcheson, president of VLSI Research in
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San Jose. "Right now, it's expensive, but the cost should come down
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fairly fast as volumes build."
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The idea of active noise reduction dates back to a 1936 patent for a
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"process of silencing sound oscillations" by German inventor Paul
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Lueg. But commercial execution required invention of the microchip.
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The concept is simple. Fight fire with fire.
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Page 1
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Here's how it works :
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Start with an irritating noise, say, that of an air compressor.
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A microphone samples the noise and sends a signal to a microchip
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analog-to-digital converter, which translates the sound waves
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into computer language. It creates a digitized blueprint of the
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sound, then passes the blueprint to a digital signal processing
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chip that analyzes the sound's magnitude and frequency.
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The digital sound processor (DSP) then computes WHAT pattern of
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sound waves would be EQUAL but OPPOSITE - a MIRROR IMAGE. (180
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degree shifted for perfect cancellation...Vangard)
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That sound profile (signature) is then converted back from a digital
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to an analog representation. An audible sound wave is created and
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amplified through speakers or a headset. When the yin-and-yang
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sound patterns collide - the whole process takes a fraction of a
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second - they largely cancel each other out. The loud air
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compressor noise becomes a quiet hum. Advanced systems continuously
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sample the ambient noise level, correcting and re-correcting. They
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follow noises as they change, such as engines accelerating.
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"Most of these systems are still in the experimental stage," says
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Mike Collins, a manager of digital signal operations at Motorola
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Corp. in Austin. "In a couple of years, it has the potential to
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become a commonplace consumer item that will make quieter
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dishwashers, quieter airplanes and so forth."
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Most of the patents required to make a DSP-based noise reduction
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system work are owned by two small U.S. companies : privately held
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Active Noise and Vibration Technology in Phoenix and publicly held
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Nose Cancellation Technologies in Stamford, Conn. They are working
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with Motorola and Analog Devices of Norwood, Mass. to develop the
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best chips. Other companies are expected to become active players
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in coming years, at least at the chip-production level.
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Active Noise says it will have headsets on the market this year
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carrying a price tag of about $250. They'll be marketed primarily
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to workers in noisy industrial settings, where they will replace
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earplugs as safety equipment.
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Unlike earplugs, which block sounds indiscriminately, the headsets
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will be programmed to target low-frequency, repetitive sounds that
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bother most people. A jackhammer operator, at least theoretically,
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will be able to operate his or her machine and still converse with a
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co-worker without shouting. As brilliant as noise reduction
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technology sounds, not everybody is getting on board yet.
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"The more mainstream approach is to try to reduce noise at the
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source," says engineer Tom Mitchell, head of the Noise Technology
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Center at General Motors Corp's Power Train Division in Pontiac,
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Mich. "Anything you add to a vehicle to susceptible to failure, and
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there's some added cost associated with a noise reduction system."
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Mr. Mitchell says GM has devoted considerable resources to reducing
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unwanted vibrations and noise in automobiles. Fluid-filled engine
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mounts, developed eight years ago, are an example of a simple device
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that eliminates noise by reducing the transfer of vibrations from
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the engine to the frame of the car.
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Page 2
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"I could bore you for hours with all the stuff we've developed,"
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says Mr. Mitchell. "Like double-wall, insulated exhause pipes and
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sound absorbers in the headliner. We devote a lot of energy to
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reducing noise, because customers tell us it's one of the best
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mechanisms they have for assessing quality." Reducing noise can get
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kind of tricky. Nobody wants road noise, thus tire makers have
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sound standards to meet.
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"On the other hand, nobody wants absolute silence. They want some
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feedback that the engine is there. That's where an electric car can
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be eerie," Mr. Mitchell says.
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The key to the noise-cancellation feature of DSP systems rests in
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the software that's built into the chips. That's where most
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research and development energies are being expended. The chip has
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to be told which sounds to attack and which to leave alone.
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"You don't want to cancel the sound of a great Porsche engine," says
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Tom Hesse, founder and chief executive officer of Active Noise in
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Phoenix. In some cases, noise suppression systems actually do more
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than eliminate an irritation or a safety hazard. They can improve
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performance. Systems are being developed to replace the entire
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exhaust system and muffler, thus eliminating the back pressure that
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the muffler creates.
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"As a result, you get up to a 5 percent improvement in gas mileage,"
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says John McCoy, president of Noise Cancellation Technologies.
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Many companies - including Boeing Co., Mercedes Benz and Whirlpool
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Corp. - confirm they are looking at noise reduction systems but
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don't want to comment on their research progress because they don't
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want to tip off their competitors about the timing of the
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introduction of improved devices. "I know there's a lot of work
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going on here, but it's highly proprietary," says Boeing spokesman
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Tom Cole.
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Meanwhile, designers at Noise Cancellation and Active Noise are busy
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drumming up interest. So far, most of their income has come from
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licensing big companies to develope their own systems for specific
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products. When they come to market, there may be some interesting
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twists.
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"We could use it to do more than reduce noise. It could create
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sounds," says Active Noise's Mr. Hesse. "We probably could make a
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Honda Civic sound like a Ferrari."
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Better yet, how about one that can tune out, "Are we there yet?"
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If you have comments or other information relating to such topics
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as this paper covers, please upload to KeelyNet or send to the
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Vangard Sciences address as listed on the first page.
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Thank you for your consideration, interest and support.
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Jerry W. Decker.........Ron Barker...........Chuck Henderson
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Vangard Sciences/KeelyNet
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If we can be of service, you may contact
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Jerry at (214) 324-8741 or Ron at (214) 242-9346
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Page 3
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