nad i podprobkowanie

clc; clear; close all;

f1= 8;
N=4;
M=2;
t1=-0.5:1/(f1*16):0.5;

sin1= sin(2*pi*f1.*t1),

sin2=zeros(1,length(sin1)*N),
sin2(1:N:length(sin2))=sin1;

sin3=sin1(1:M:length(sin1));

t1= linspace(-0.5,0.5,length(sin1))

t2= linspace(-0.5,0.5,length(sin2))

t3= linspace(-0.5,0.5,length(sin3))

B1= fir1(20,1/(2*N));
B2= fir1(20,1/(2*M));

sinf2=filter(B1,1,sin2);
sinf3=filter(B2,1,sin3);

dft1=fft(sin1),
dft2=fft(sinf2),
dft3=fft(sinf3),

figure(1);
subplot(2,1,1)
plot(t1, sin1,'.-'); hold on; plot(t2,sinf2,'.');
subplot(2,1,2)
plot(t1, sin1,'.-'); hold on; plot(t3,sinf3,'o');

figure(2);
subplot(3,1,1)
plot(abs(dft1));
subplot(3,1,2)
plot(abs(dft2));
subplot(3,1,3)
plot(abs(dft3));