Presented by:ID

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United Arab Emirates UniversityCollege of
EngineeringGraduation Projects Unit
DESIGN OF SINGLE-CHANNEL FEEDFORWARD ACTIVE
NOISE CONTROL SYSTEM

• Presented by ID
• Abdulla Wasfi 199901531
• Ali Ahmed 200101757
• Ibrahim Muhammed 200235830
• Bassim Al-Kahlout 200101874
• Advisor Dr. Muhammed Taher Aktar

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Outline

• Executive Summary.
• Objectives and Scope.
• Background Theory.
• Simulation Environment.
• Prototype.
• Results.
• Problems.
• Conclusion.

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Executive Summary(1/7)

• The project is about designing of single channel
  feedforward active noise control system (ANC).
• Basic idea
• Canceling the low frequency unwanted disturbance.

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Executive Summary(2/7)

• Types of noise

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Executive Summary(3/7)

• How?
• Generating an anti-phase signal.

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Executive Summary(4/7)
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Executive Summary(5/7)

• More details

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Executive Summary(6/7)

• ANC performance depends on
• The wavelength of the primary and the secondary
  source.
• The separation distance between the two sources.
• Ideal cancellation when d 0.

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Executive Summary(7/7)

• The plan for the project is
• Basic study.
• Prototype development.
• System identification.
• Simulation and implementation.

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Importance of the project

• Active noise cancellation/control (ANC) technique
  has an application to a wide variety of problems.
• Investigate ANC technique for real life
  application.
• design an ANC system that is able to record
  noise, and process it, which when played back,
  will cancel the unwanted noise.

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Objective and scope

• Implementing a feed-forward ANC technique for the
  purpose of canceling low frequency and periodic
  undesired noise in an enclosed duct.

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Active Noise Control (ANC)

• Passive techniques in the acoustic noise
  cancellation have been used in the past.
• ANC system involves electromechanical system that
  cancels the primary noise based on the
  superposition principle.

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Active Noise Control (ANC)

• ANC categories
• Duct noise one-dimensional ducts such as
  ventilation ducts, exhaust ducts,
  air-conditioning ducts, pipe-work, etc.
• Interior noise noise within an enclosed space.
• Personal hearing protection a highly compacted
  case of interior noise.
• Free space noise noise radiated into open space.

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Adaptive Active Control

• characteristics of the acoustic noise source and
  the environment are time varying.
• The frequency content, amplitude, phase, and
  sound velocity of the undesired noise are not
  stationary.
• Adaptive filters adjust their coefficients to
  minimize an error signal and can be realized as
  FIR, IIR.

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ANC Systems (1/4)

• Broadband Feedforward ANC System.

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ANC Systems (2/4)

• Narrowband Feedforward ANC System.

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ANC Systems (3/4)

• Feedback ANC Systems

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ANC Systems (4/4)

• Multiple-Channel ANC System

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Simulation Environment (1/2)

• Matlab program was used to model the system
• Software consists of three main parts
• Noise Generator
• Primary path filter
• LMS Adaptive filter

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Simulation Environment (2/2)
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Noise Generation
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Primary Path Filter

• Digital Butterworth band pass filter (200 1000
  Hz)

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LMS Adaptive Filter

• The LMS adaptive algorithm was written in Matlab
• The coefficients were been taken from a book
  (Active noise control system)
• Filtered noise will be processed through LMS
  adaptive algorithm
• to update the coefficients (reduce the error).

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OffLine Test (1/4)

• Two experiments have been done offline to get the
  impulse response of P(z) and S(z)
• Procedures of the two experiments
• Generating random noise Sn by MATLB.
• Filtering the random noise through a Band pass
  filter 200 1000.
• The filtered noise Yn will be transmitted
  into the duct through a loudspeaker.
• At the end of the duct, the noise will be sensed
  and measured dn by a microphone.

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OffLine Test (2/4)

• Above procedures will be repeated 10 times and
  the average of dn and Yn will be calculated.
• The averaged Yn and dn will be introduced to
  LMS algorithm code and will be run through a
  MATLAB. After convergence, expression of W(z)
  will be determined.
• W(z) P(z).

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OffLine Test (3/4)
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OffLine Test (4/4)
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Prototype(1/10)

• Materials to be used in modeling the system
• Function generator
• ANC System Components
• Plant
• Sensors
• Actuators
• Controllers

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Prototype(2/10)

• Function generator
• The undesired noise is a low frequency originates
  in a fan, air conditioning / heating unit and
  engines.
• Function generator will be used to produce
  frequencies 100 - 600 Hz.
• Amplify the signal output it through a speaker
  (source of the noise).

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Prototype(3/10)

• The Plant is the volume or space within a volume
  to be controlled
• Examples
• Air Conditioning duct.
• Ventilation duct.

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Prototype(4/10)

• The Plant
• 8 diameter PVC pipe 0.2 m.
• Approximately 1.5 m in length.

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Prototype(5/10)

• Sensors
• Devices that senses some conditions.
• Examples
• Microphones.
• Transducers.
• Accelerometers.
• Microphones devices used to sample the
  disturbing noise that will be cancelled.
• 8 Microphones will be used.

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Prototype(6/10)

• Why Shure SM-57?
• Low cost.
• Low impedance.
• High sensitivity.

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Prototype(7/10)

• Actuators
• The physical meaning of producing the processed
  output noise.
• Examples
• Speakers.
• 2 speaker powered by an amplifier.
• Speaker will be introduced to the plant via a Y
  fitting at the third quarter of the duct.

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Prototype(8/10)

• Controllers
• Devices used to process the input noise before
  sending the output to the Actuator.
• Used in conjunction with the Sensors.
• May consist of
• DSP and related Software.
• Texas Instruments Digital Signal Processing (DSP)
  Board in conjunction with a PC.
• TMS320C25 DSP.

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Prototype(9/10)

• Why TMS320 DSP?
• It combines
• High speed.
• Flexibility.
• Low cost.
• TMS320 can execute an instruction in 80 ns.

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Prototype(10/10)
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Results (1/6)
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Results (2/6)
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Results (3/6)
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Results (4/6)
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Results (5/6)
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Results (6/6)
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Problems

• DSP kit.
• Debugging.
• Microphones.
• DAC.

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Conclusion(1/3)

• The ANC system was studied and analyzed.
• Its main concept, history, background, benefits
  and application were all discussed.
• LMS FxLMS was implemented by MATLAB.

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Conclusion(2/3)

• A simulation environment was created
• It consists of
• Noise generation.
• Primary path.
• LMS FxLMS filtering.

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Conclusion(3/3)

• The materials of the project were selected and
  bought.
• The prototype was done.

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Thanks For Your Listening