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The Noise Eliminator Using Fast Fourier Transform in CCStudios and MatLab. Presented to: Dr Li By: Megan Myles & David Jackson. The Noise Eliminator. Researching Project Idea Visited Various DSP Websites Implemented idea in MatLab to test the concept

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The noise eliminator using fast fourier transform in ccstudios and matlab

The Noise Eliminator Using Fast Fourier Transform in CCStudios and MatLab

Presented to: Dr Li

By: Megan Myles & David Jackson


The noise eliminator
The Noise Eliminator CCStudios

Researching Project Idea

  • Visited Various DSP Websites

  • Implemented idea in MatLab to test the concept

  • Interviewed Dr. Li and other engineers about the noise eliminator



Meetings contd
Meetings contd. CCStudios



Steps followed in matlab
Steps followed in MatLab CCStudios

  • Input wave file into MatLab as a vector

  • Run noisy signal through a Fourier Transform

  • Change all values of the signal points to zero except the first and last few.

  • Run signal through an inverse Fourier transform

  • Take only real part of ifft

  • This final signal will be the clear signal extracted from the noise



Matlab code
MatLab Code CCStudios

fs=22050;

s=20000;

x=wavread('5000noisywav.wav');

wavplay(x,fs);

f=fft(x);

f(s+1:220500-s,:)=0;

i=real(ifft(f));

wavplay(i,fs);





Ccstudio
CCStudio CCStudios


Isrs c in cc studio
ISRs.c in CC Studio CCStudios

#include "..\..\..\Common_Code\DSK_Config.h“

#include "math.h"

#include "frames.h"

// frame buffer declarations

#define BUFFER_COUNT 1024 // buffer length in McBSP samples (L+R)

#define BUFFER_LENGTH BUFFER_COUNT*2 // two shorts read from

s = 100;

for(i=s;i < BUFFER_COUNT-s;i++){

x[i].real = 0.0;

x[i].imag = 0.0;


What we learned
What We Learned CCStudios

  • Fast Fourier Transform - Chapter 8

    FFT is a fast way for computers to calculate the Fourier transform.

    The difference between the FFT and IFFT is simply the division by N and the negative powers of the twiddle factors.

    The algorithm can be used for both the FFT and IFFT.


Learning contd
Learning Contd. CCStudios

  • Using the FFT for filtering

    As the order of a filter increases the time required to calculate the output value associated with each input sample also increases.

  • Frame based filtering helps increase the overall efficiency of the filtering and reduces the time required to pass various samples. (Chapter 7)


Conclusion
Conclusion CCStudios

Noise filters have many uses:

  • Filter engine noise from car audio

  • Filter static from cell phone transmissions

  • Even filter an image for better clarity

  • Noise filters improve the quality of life around the world


ad