MATLAB program for the design and implementation of Chebyshev low pass filter

Program code

%Chebyshev low pass filter

clc;

clear all;

close all;

fp=input('Please enter the pass band frequency: ');

fs=input('Please enter the stop band frequency: ');

rp=input('Please enter the pass band attenuation: ');

rs=input('Please enter the stop band attenuation: ');

sf=input('Please enter the sampling frequency: ');

wp=2*fp/sf;

ws=2*fs/sf;

[n,wn]=cheb1ord(wp,ws,rp,rs);

[b,a]=cheby1(n,rp,wn,'low');

freqz(b,a);

title('Chebyshev low pass filter');

Example of output

Please enter the pass band frequency: 2000

Please enter the stop band frequency: 1600

Please enter the pass band attenuation: .4

Please enter the stop band attenuation: 50

Please enter the sampling frequency: 8000 

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MATLAB program for the design and implementation of Butterworth low pass filter

Program code

clc;
clear all;
close all;
fp=input('Please enter the first pass band frequency: ');
fs=input('Please enter the first stop band frequency: ');
rp=input('Please enter the pass band attenuation: ');
rs=input('Please enter the stop band attenuation: ');
sf=input('Please enter the sampling frequency: ');
wp=2*fp/sf;
ws=2*fs/sf;
[n,wn]=buttord(wp,ws,rp,rs);
[b,a]=butter(n,wn,'low');
freqz(b,a);
title('Butterworth Low Pass Filter');

Example of output

Please enter the first pass band frequency: 2000

Please enter the first stop band frequency: 1600

Please enter the pass band attenuation: .5

Please enter the stop band attenuation: 53

Please enter the sampling frequency: 9500

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MATLAB program for Ideal Low Pass Linear Phase Fir Filter

Program Code

clc;
close all;
clear all;
wc=input('Input the cut-off frequency in radians(less than pi)');
M=input('Input the length of ideal filter');
if wc>pi
    error('cut-off frequency should be less than pi')
    return
end
alpha=(M-1)/2;
n=0:1:(M-1);
m=n-alpha+eps;
hd=sin(wc*m)./(pi*m);
if nargout==0
    stem(n,hd);
    title('Impulse response of ideal low pass filter');
    xlabel('n');
    ylabel('hd(n)');
end

                      Example of Output

Input the cut-off frequency in radians(less than pi)    3
Input the length of ideal filter     50

ans =

  Columns 1 through 7 

   -0.0123    0.0133   -0.0141    0.0147   -0.0151    0.0152   -0.0149

  Columns 8 through 14 

    0.0143   -0.0134    0.0120   -0.0102    0.0079   -0.0050    0.0016

  Columns 15 through 21 

    0.0025   -0.0075    0.0134   -0.0207    0.0297   -0.0412    0.0569

  Columns 22 through 28 

   -0.0800    0.1194   -0.2074    0.6350    0.6350   -0.2074    0.1194

  Columns 29 through 35 

   -0.0800    0.0569   -0.0412    0.0297   -0.0207    0.0134   -0.0075

  Columns 36 through 42 

    0.0025    0.0016   -0.0050    0.0079   -0.0102    0.0120   -0.0134

  Columns 43 through 49 

    0.0143   -0.0149    0.0152   -0.0151    0.0147   -0.0141    0.0133

  Column 50 


   -0.0123

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