Spectrum Analysis using DFT

 Program:

clc;
clear;
close;
fs=125;
fm=10;
m=2;
t=0.0001:1/fs:m/fm;
x=3*cos(2*%pi*fm*t);

N=(m*fs/fm)
for k=1:N
    X1(k)=0;
    for n=1:length(x)
        X1(k)=X1(k)+x(n).*exp((-%i)*2*%pi*(n-1)*(k-1)/N)
    end
end

subplot(1,2,1);
plot2d3(t,x);

k=0:N-1;
f=k*fs/N;
subplot(1,2,2);
plot2d3(f,abs(X1));

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