MATLAB program for unfolding and unwrapping of DFT

Program Code

%Unfolding and Unwrapping of DFT
clc;
close all;
clear all;
x=input('Enter the sequence x= ');
N=input('Enter the length of the DFT N= ');
len=length(x);
if N>len
    x=[x zeros(1,N-len)];
elseif N<len
    x=x(1:N);
end
i=sqrt(-1);
w=exp(-i*2*pi/N);
n=0:(N-1);
k=0:(N-1);
nk=n'*k;
W=w.^nk;
X=x*W;
disp(X);
subplot(411);
stem(k,abs(X));
title('Magnitude plot of unwrapped sequence ');
subplot(412);
stem(k,angle(X));
title('Phase plot ofunwrapped sequence ');
y=X(floor(N/2)+1:N);
Y=[y X(1:floor(N/2))];
subplot(413);
stem(k,abs(Y));
title('Magnitude plot of unfolded spectrum ');
subplot(414);
stem(k,angle(Y));
title('Phase plot of unfolded spectrum ');

Example of Output

Enter the sequence  x= [1 1 2 2 3 3 2 2 1 1]
Enter the length of the DFT  N= 69
  Columns 1 through 4 

  18.0000            16.1310 - 7.0067i  11.1882 -11.9796i   4.8688 -13.6995i

  Columns 5 through 8 

  -0.8338 -12.1898i  -4.4438 - 8.5762i  -5.5078 - 4.4810i  -4.5846 - 1.2845i

  Columns 9 through 12 

  -2.7880 + 0.3832i  -1.1687 + 0.7107i  -0.2635 + 0.3733i  -0.0093 + 0.0449i

  Columns 13 through 16 

   0.0082 + 0.0394i   0.1772 + 0.2510i   0.5978 + 0.3635i   1.0701 + 0.1471i

  Columns 17 through 20 

   1.2925 - 0.3622i   1.1048 - 0.8989i   0.6049 - 1.1673i   0.0716 - 1.0466i

  Columns 21 through 24 

  -0.2337 - 0.6577i  -0.2394 - 0.2563i  -0.0873 - 0.0379i   0.0000 + 0.0000i

  Columns 25 through 28 

  -0.0920 + 0.0400i  -0.2666 + 0.2855i  -0.2763 + 0.7775i   0.0905 + 1.3226i

  Columns 29 through 32 

   0.8264 + 1.5948i   1.6598 + 1.3503i   2.1917 + 0.6141i   2.1373 - 0.2938i

  Columns 33 through 36 

   1.5176 - 0.9229i   0.6738 - 0.9545i   0.0829 - 0.3990i   0.0829 + 0.3990i

  Columns 37 through 40 

   0.6738 + 0.9545i   1.5176 + 0.9229i   2.1373 + 0.2938i   2.1917 - 0.6141i

  Columns 41 through 44 

   1.6598 - 1.3503i   0.8264 - 1.5948i   0.0905 - 1.3226i  -0.2763 - 0.7775i

  Columns 45 through 48 

  -0.2666 - 0.2855i  -0.0920 - 0.0400i  -0.0000 + 0.0000i  -0.0873 + 0.0379i

  Columns 49 through 52 

  -0.2394 + 0.2563i  -0.2337 + 0.6577i   0.0716 + 1.0466i   0.6049 + 1.1673i

  Columns 53 through 56 

   1.1048 + 0.8989i   1.2925 + 0.3622i   1.0701 - 0.1471i   0.5978 - 0.3635i

  Columns 57 through 60 

   0.1772 - 0.2510i   0.0082 - 0.0394i  -0.0093 - 0.0449i  -0.2635 - 0.3733i

  Columns 61 through 64 

  -1.1687 - 0.7107i  -2.7880 - 0.3832i  -4.5846 + 1.2845i  -5.5078 + 4.4810i

  Columns 65 through 68 

  -4.4438 + 8.5762i  -0.8338 +12.1898i   4.8688 +13.6995i  11.1882 +11.9796i

  Column 69 


  16.1310 + 7.0067i

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