NOISE CANCELLATION

Click here to load reader

  • date post

    05-Feb-2016
  • Category

    Documents

  • view

    138
  • download

    3

Embed Size (px)

description

NOISE CANCELLATION http://DoctorD.WebHop.Net. INTRODUCTION TECHNOLOGY APPLICATIONS DEMONSTRATION SUMMARY. NOISE CANCELLATION INTRODUCTION. NOISE REDUCTION TECHNIQUES MECHANICAL DESIGN BALANCE TRANSIENTS RESONANCES PASSIVE ATTENUATION ENERGY ABSORBING MATERIALS COMPLIANT MOUNTS - PowerPoint PPT Presentation

Transcript of NOISE CANCELLATION

  • NOISE CANCELLATIONhttp://DoctorD.WebHop.NetINTRODUCTIONTECHNOLOGYAPPLICATIONSDEMONSTRATIONSUMMARY

    Active Noise Cancellation

  • NOISE CANCELLATIONINTRODUCTIONNOISE REDUCTION TECHNIQUESMECHANICAL DESIGNBALANCETRANSIENTSRESONANCESPASSIVE ATTENUATIONENERGY ABSORBING MATERIALS COMPLIANT MOUNTS ACTIVE SYSTEMS: NOISE CANCELLATIONAPPLICATIONSSTATUS"NOISE CANCELLATION TECHNOLOGY IS A PRACTICAL SOLUTION TO REAL WORLD PROBLEMS"

    Active Noise Cancellation

  • NOISE CANCELLATIONANTI-NOISE"ACTIVE NOISE CANCELLATION DOES NOT MASK THE NOISE, IT REMOVES A SIGNIFICANT PORTION OF THE NOISE FROM THE ENVIRONMENT"

    Active Noise Cancellation

  • NOISE CANCELLATIONTECHNOLOGYNOISEBROAD BANDTURBULENT OR RANDOM NOISENARROW BANDTONAL OR HARMONIC NOISEPASSIVE NOISE CONTROLLOCALIZE VIBRATION AND ABSORB ENERGYEFFECTIVE AT HIGH FREQUENCIESACTIVE CANCELLATIONTWO BASIC APPROACHES BROAD BAND -ADAPTIVELY FILTER THE SIGNAL FROM AN "UPSTREAM" SENSOR TO CREATE THE ANTI-NOISE SIGNAL SYNCHRONOUS - ADAPTIVELY SYNTHESIZE AN ANTI-NOISE SIGNAL WITH A-PRIORI KNOWLEDGE OF THE BASIC "NOISE CYCLE" RATEEFFECTIVE AT LOW FREQUENCIES "A GOOD SOLUTION USUALLY REQUIRES A COMBINATION OF PASSIVE AND ACTIVE TECHNIQUES"

    Active Noise Cancellation

  • NOISE CANCELLATIONEXAMPLE APPLICATIONSAT SOURCEMUFFLERALONG A TRANSMISSION PATHIN-DUCT FAN NOISECOMPLIANT MOUNTAT THE EARHEADSETBroadbandSelective Narrow BandQUIET ZONECabin QuietingIN-WIRECOMMUNICATIONS"ENGINEERING SOLUTIONS TO NOISE PROBLEMS REQUIRES AS MUCH REAL WORLD APPLICATION KNOWLEDGE AS IT DOES KNOWLEDGE OF ACTIVE NOISE CANCELLATION TECHNOLOGY"

    Active Noise Cancellation

  • AT SOURCE: MUFFLER(NARROW BAND NOISE CANCELLATION)IT IS USUALLY BEST TO CANCEL THE NOISE AS CLOSE AS POSSIBLE TO THE SOURCE"

    Active Noise Cancellation

  • AT SOURCE: MUFFLER(CONTINUED)CHARACTERISTICSSTRAIGHT THROUGH PASSIVE MUFFLER REDUCES BACKGROUND AND HIGH FREQUENCY NOISEACTIVE CANCELLATION AT THE END OF THE EXHAUST GLOBALLY REDUCES TONAL NOISE COMPONENTS TO THE BACKGROUNDBENEFITSLOW BACK PRESSUREFUEL ECONOMYQUIETSIZE AND WEIGHTAPPLICATIONSPRIMARY POWER EXHAUSTAUXILIARY POWER GENERATORS (EXHAUST NOISE)BULK TRANSFER VACUUM SYSTEMSCOMPRESSOR INLET NOISE

    Active Noise Cancellation

  • Vacuum MufflerApplication: 100 horsepower diesel vacuum. Used to load and unload railroad cars (CSX MasterVac 10/1990)Noise SourcesVacuum Exhaust: An Active Muffler, along with a straight-through, passive muffler.Diesel Exhaust: a better passive muffler.Engine Block: Passive housing.Vibration: Compliant mounts.

    Active Noise Cancellation

  • Vacuum Muffler (Continued)The quiet system loads/unloads a rail car 20% faster than the noisy system it replaced.

    Active Noise Cancellation

  • CSX MasterVac

    Active Noise Cancellation

  • Diesel Engine MufflerApplication: 450 horsepower diesel engine. 522 in3, 2-stroke Used to generate electrical power (Detroit Diesel 6V-92 at 1800 RPM)Noise SourcesExhaust: An Active Muffler, along with a straight-through, passive muffler.Air Intake: Air filterEngine Block: Passive housing.Vibration: Compliant mounts.

    Active Noise Cancellation

  • Diesel Muffler Results(Demonstration Audio)The Active muffler system is 20% smaller than the conventional passive muffle it replaced.

    Active Noise Cancellation

  • Along a Transmission Path(Broadband Noise Cancellation) "FEED FORWARD CANCELLATION IS THE CLASSICAL APPROACH AND IS OFTEN HIGHLIGHTED IN THE TECHNICAL LITERATURE"

    Active Noise Cancellation

  • CONTROLLING VIBRATION"CONTROLLING VIBRATION NEAR THE SOURCE CAN GREATLY REDUCE ACOUSTICAL NOISE AND REDUCE WEAR"

    Active Noise Cancellation

  • COMPLIANT MOUNT(CONTINUED)CHARACTERISTICSROTATING MACHINE FLOATS FREELY AT VIBRATION FREQUENCIESNO VIBRATION ENERGY IS TRANSMITTED THROUGH THE MOUNTFAIL SAFE - THE PASSIVE MOUNT IS STILL THERE IF THE ACTIVE SYSTEM STOPS WORKINGBENEFITSOPERATOR COMFORT - VIBRATION REDUCEDSECONDARY ACOUSTICAL NOISE ELIMINATEDREDUCED WEARAPPLICATIONSENGINES AUXILIARY GENERATORSREFRIGERATION UNITSCOMPRESSORS

    Active Noise Cancellation

  • AT THE EAR: SELECTIVE HEADSET(NARROW BAND NOISE CANCELLATION)"A SELECTIVE NOISE CANCELING HEADSET CAN IMPROVE WORKER SAFETY BY ENHANCING PERCEPTION OF WARNING SIGNALS"

    Active Noise Cancellation

  • AT THE EAR: HEADSET(CONTINUED)CHARACTERISTICSSELECTIVEREDUCE TONAL COMPONENTS TO THE BACKGROUND NOISE LEVELBENEFITSSAFETYHEARING PROTECTIONCOMFORTAPPLICATIONSEQUIPMENT OPERATORS (IN-CAB)GENERAL WORK SITE

    Active Noise Cancellation

  • Analog Heaset(Broadband Noise Cancellation)An open-back, analog, noise canceling headset has good low-frequency attenuation and passes higher frequencies without attenuation.

    Active Noise Cancellation

  • Zone Cancellation(Interacting Channels)"PLACEMENT OF SPEAKERS AND MICROPHONES REQUIRES CAREFUL ACOUSTICAL ENGINEERING TO PRODUCE A WELL BEHAVED SYSTEM"

    Active Noise Cancellation

  • Saab 2000 TurbopropThe SAAB 2000 aircraft (50 passengers) has an ANC system for reducing the noise in the cabin. http://www.ultraquiet.comThis is achieved by measuring the sound with microphones (green) and generating canceling sound waves using speakers (red).The ANC system has 72 microphones and 36 speakers (a complex multivariable problem).A key advantage is a dramatic weight savings compared to passive treatments alone.Sonograms (a graphical representation of sound) left shows sound levels within the aircraft while in flight. Blues and greens represent lower levels, oranges and reds are higher.ONOFF

    Active Noise Cancellation

  • Zone Cancellation(CONTINUED)CHARACTERISTICSEFFECTIVE ON TONAL NOISE BELOW 250 HZSOPHISTICATED ALGORITHM COMPENSATES FOR INTERACTIONS AMONG MICROPHONES AND SPEAKERSBENEFITSCOMFORTSAFETYHEARING PROTECTIONAPPLICATIONSEQUIPMENT CAB (In production turboprop aircraft)SITE OFFICE

    Active Noise Cancellation

  • NOISE CANCELLATIONSUMMARYPRACTICAL SOLUTION TO SELECTED REAL WORLD PROBLEMSSIGNIFICANTLY REDUCES NOISE AND VIBRATIONCOSTS ARE OFTEN COVERED BY IMPROVED EFFICIENCIESSAFETYACCIDENTSHEARING PROTECTIONPRODUCTIVITY GAINSBetter CommunicationsBetter ThroughputEnergy Savings

    Active Noise Cancellation

    Demonstration: Audio tape of Detroit Diesel 6V92 Generator and ANC headsetNot total cancellationIn use for quieting turboprop commuter aircraft (Saab 2000 50 passengers, 72 microphones, & 36 speakers)Originally developed by Noise Cancellation Technologies