bagas ganteng

fs = 8000; %frequency sampling
t = 0:1/fs:1; % time range
x = 4*cos(2*pi*400*t)+4*cos(2*pi*900*t+0.5*pi)+5*cos(2*pi*400*t+0.25*pi); %signal x
%H(z) = Y(z)/X(z) = (1 + 3 2*-2)/ (1 - 1/3 z*-1)
b = [0.0201 0.0000 -0.0402 0.0000 0.0201 ]
a = [1.0000 -2.1192 2.6952 -1.6924 0.6414 ]

y = filter(b,a,x); % filtering
%fft sinyal awal
Ak1=abs(fft(y))/length(x);
k1=0:1:length(x)-1;
f1=k1*fs/length(x);
%fft sinyal setelah filter
Ak2=abs(fft(y))/length(y);
k2=0:1:length(y)-1;
f2=k2*fs/length(y);
%plot
figure(1);
subplot(2,1,1)
plot(f1,Ak1)
subplot (2,1,2)
plot(f2,Ak2)
figure(2);
freqz(b,a,512,fs); %frekuensi respon filter