Now I'm trying to understand and implement the zero-padding work in my example. As I know, meaningless zero values are affect to better DFT result. So I want to see how zero-padding works.
clear all
clc
fs = 50; %50Hz
T = 1/fs;
N = 8;
t = (0:N-1)*T;
y = 5+cos(2*pi*12.5*t)+sin(2*pi*18.75*t);
X=zeros(1,N);
for k = 0:N-1
for n = 0:N-1
X(k+1) = X(k+1) + y(n+1)*exp(-j*(2*pi/N)*k*n);
end
end
x_mag = abs(X);
f_2 = fs*(0:(N-1))/N;
stem(f_2,x_mag,'-ok','linewidth',2,'MarkerFaceColor','black');
For N=8:
For N=80:
But I feel hard to implement the increasing zero padding in my example code. Would you please show me how I can increase the zero-pad?
I found the better result when I increased the $N$ number to 80 from 8. But I'm not sure if increasing $N$ means increasing the zero-pad.