ANC Project

8/7/2019 ANC Project

1/22

Active Noise Cancellation

Dr. FarrukhDr. FarrukhDepartment of Electrical & Electronics Engineering,Department of Electrical & Electronics Engineering,

College of Engineering,College of Engineering,

University Tenaga Nasional,University Tenaga Nasional,

Jalan KajangJalan Kajang--Puchong,Puchong,

43009 Kajang,43009 Kajang,

Selangor, MALAYSIA.Selangor, [email protected]


2/22

Description of paper Use of TMS320C5402 DSK-single

TMS320C6701 EVM dual channel channelActive Noise Cancellation in duct system

Uses feedback + feedforward topology -designed to cancel narrowband periodic

tones.


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Problem Description!!!!

Unwanted sound thatis often loud and irritating

Industrial equipment

Damaging to human from both

a physical and psychological aspect

Active Noise Cancellation???Reason

What is Noise ?????


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How does Active Noise Cancellation(ANC) works ?

Basic principles by introducing a canceling anti-noisesignal that has the same amplitude but the exactopposite phase and resulting a reduction noise signal

Identical and in phaseVolumes increases

Out of phaseVolumes decreases

Active noise cancellation


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Approaches of ANC

Feedforward Topology Reference noise andcancelled noise are used

2 inputs and 1 output

Feedback Topology only cancelled noiseare used one input and one outpu

Use of TMS320C5402 DSK-singlechannel Active Noise Cancellation

in duct system

Hardware


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Feedback TopologyHardware

W(z)

S^(z)

L MS

EstimateSecondaryPath,S^(z)

SecondaryPath,S(z)

x(n)

x^(n)

y(n)

e(n)

Duct system

to estimate primarynoise and use it as areference

DSP System

X(z)= E(z) + S(z)Y(z)

Need to estimate thesecondary path transferfunction

y(n)


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Feedback Experimental SetupFeedback Experimental Setup--ANCANC

DSP TMS320C5402 DSK

Amplifier

Noise loudspeaker

Input noiseCanceling loudspeaker

Canceling zone

Amplifier

microphone

Secondary Path

Hardware

LMS Algorithm

INOUT

e(n)

y(n)

S(z)x(n)


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Feedforward Topology

Estimationof S(z),

(z)LMS

SecondaryPath,S(z)

x(n)

x^(n)

y(n)

e(n)

Duct system

Coherent input iscaptured, filteredand feed into LMS

DSP System

Estimation of thesecondary pathtransfer function isobtained byidentification

processe(n)

Primaryfunction, P(z)

y(n)

d(n)

W(z)


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Feedforward ExperimentalFeedforward ExperimentalSetupSetup

Noise speaker

Input noiseCanceling speaker

Canceling zone

Amplifier

microphone

Secondary Path

Hardware

TMS320C6701 EVM DSP

e(n)

y(n)

S(z)x(n)


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Least Mean Square (LMS) Algorithm

Software

)()()( iyidie!

!

!1

0

)()(N

k

kkixbiy

The outputThe output

The errorThe error

Update the weightsUpdate the weights

)()(2)()1( kixiebb ikik ! F


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Secondary path S(z) duct modeling

Canceling loudspeaker

Amplifier

microphone

S(z)

LMSAlgorithm

Result of identification ofthe secondary path


12/22

Single channel cancellation results

InputF

requency =120Hz


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Without cancellation

With cancellation

Input Frequency = 70 + 80 Hz


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Cancellation result on

70+80+100+110+120+130Hz


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Dual Channel cancellation Results

InputF

requency =80Hz

No cancellationWith cancellation


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Input Frequency = 40+70Hz

no cancellation

cancellation


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Cancellation result on

40 + 70 + 80Hz

no cancellationcancellation


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Conclusions ANC was first time attempted in Malaysia and

obtained compatible results.

Integrated programming of DSP was achieved

without any external aid or training. This work yields Masters thesis and research

papers accepted by local and international

conferences. The expertise developed is now being shared

with other groups, projects and laboratory workin COE.


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Future Scope

Acoustic wave propagation in ductboundary is investigated with PDE FiniteElement method will be the future direction

Boundary value conditions at the exhaustof duct can be studied with FEM

Build dedicated DSP hardware for

embedded standalone ANC systemPCB for audio amplifiers and speakers are

needed for mobility of test rig


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FINITEELEMENTMETHOD

ANALY

SI

S OF

DUCT

SY

STEM


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ACCOUSTIC ENERGYINSIDETHE

DUCT


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The endThe end

ANC Project

Documents

Transcript of ANC Project