The Noise Eliminator Using Fast Fourier Transform in CCStudios and MatLab

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The Noise Eliminator Using Fast Fourier Transform in CCStudios and MatLab

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The Noise Eliminator Using Fast Fourier Transform in CCStudios and MatLab

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The Noise Eliminator Using Fast Fourier Transform in CCStudios and MatLab

Presented to: Dr Li

By: Megan Myles & David Jackson

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

- 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

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);

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

#include "math.h"

#include "frames.h"

// frame buffer declarations

#define BUFFER_COUNT1024 // 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;

- 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.

- 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)

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