Upsampling & Low pass filtering using FFT | MATLAB

Code:

%%

clc

clear all

close all

%%

N=32;

n=0:31;

w=2*pi/N;

x=sin(w*n);

stem(n,x);

%%

k1=0:31;

g=fft(x,32);

stem(k1,abs(g));

%%

k=2;

Y=[];

j=k-1;

for i=1:length(x)

    Y=[Y x(i)];

    if(i~=length(x))

    for m=1:j

        Y=[Y 0];

    end

    end

end

stem(Y);

%%

rs=fft(Y,length(Y));

k=0:length(Y)-1;

stem(k,abs(rs));

%%

subplot(2,1,1);

g=fft(x,32);

stem(k1,abs(g));

subplot(2,1,2);

k=0:length(Y)-1;

stem(k,abs(rs));

%%

rs(28)=0;

rs(29)=0;

rs(30)=0;

rs(31)=0;

rs(32)=0;

rs(33)=0;

rs(34)=0;

rs(35)=0;

r1=ifft(rs);

stem(real(r1));