BAB IV
TRANSFORMASI FOURIER DISKRIT
clc; close all; clear all;
L =5; N = 40; k = [-N/2:N/2];
n = 0:N-1;
xn = [ones(1,L), zeros(1,N-L)];
Xk = dft(xn,N);
magXk = abs([Xk(N/2+1:N) Xk(1:N/2+1)]);
subplot '211'; stem(n,xn);
xlabel('n'); ylabel('xn)')
title ('sinyal xn')
subplot '212'; stem(k,magXk);
xlabel('k'); ylabel('Xtilde(k)')
title ('DFT of SQ. vave: L=5, N=40')
figure;
L =6; N = 60; k = [-N/2:N/2];
n = 0:N-1;
xn = [ones(1,L), zeros(1,N-L)];
Xk = dft(xn,N);
magXk = abs([Xk(N/2+1:N) Xk(1:N/2+1)]);
subplot '211'; stem(n,xn);
xlabel('n'); ylabel('xn)')
title ('sinyal xn')
subplot '212'; stem(k,magXk);
xlabel('k'); ylabel('Xtilde(k)')
title ('DFT of SQ. vave: L=6, N=60')
figure;
L =7; N = 80; k = [-N/2:N/2];
n = 0:N-1;
xn = [ones(1,L), zeros(1,N-L)];
Xk = dft(xn,N);
magXk = abs([Xk(N/2+1:N) Xk(1:N/2+1)]);
subplot '211'; stem(n,xn);
xlabel('n'); ylabel('xn)')
title ('sinyal xn')
subplot '212'; stem(k,magXk);
xlabel('k'); ylabel('Xtilde(k)')
title ('DFT of SQ. vave: L=7, N=80')
figure;
L =8; N = 100; k = [-N/2:N/2];
n = 0:N-1;
xn = [ones(1,L), zeros(1,N-L)];
Xk = dft(xn,N);
magXk = abs([Xk(N/2+1:N) Xk(1:N/2+1)]);
subplot '211'; stem(n,xn);
xlabel('n'); ylabel('xn)')
title ('sinyal xn')
subplot '212'; stem(k,magXk);
xlabel('k'); ylabel('Xtilde(k)')
title ('DFT of SQ. vave: L=8, N=100')
%PERCOBAAN 2 iqbal
n = 0:1:49; x = n.*exp(-0.3*n);
n1 = [0:24]; y1=x(1:1:25);
subplot '221'; stem(n1,y1); title 'Sinyal xn 0<=n<=24';xlabel 'n2';
Y1 = dft(y1,25); magY1 = abs(Y1(1:1:13));
k1 = 0:1:12; w1 = 2*pi/25*k1;
subplot '222'; plot(w1/pi,magY1); title 'Magnitud Y1 iqbal';
xlabel 'frequency in pi unit';
n2 = [0:1:49]; y2 = [x(1:1:25) zeros(1,25)];
subplot '223'; stem(n2,y2); title 'Sinyal xn 0<=n<=24+25 iqbal'; xlabel
'n2';
Y2 = dft(y2,50); magY2=abs(Y2(1:1:26));
k2 = 0:1:25; w2 = 2*pi/50*k2;
subplot '224'; plot(w2/pi,magY2); title 'Magnitud Y2 iqbal';
xlabel 'frequency in pi unit';
figure;
n = 0:1:99; x = n.*exp(-0.3*n);
n1 = [0:24]; y1=x(1:1:25);
subplot '221'; stem(n1,y1); title 'Sinyal x 0<=n<=24';xlabel 'n2';
Y1 = dft(y1,25); magY1 = abs(Y1(1:1:13));
k1 = 0:1:12; w1 = 2*pi/25*k1;
subplot '222'; plot(w1/pi,magY1); title 'Magnitud Y1 iqbal';
xlabel 'frequency in pi unit';
n2 = [0:1:99]; y2 = [x(1:1:25) zeros(1,75)];
subplot '223'; stem(n2,y2); title 'Sinyal x 0<=n<=24+75 iqbal'; xlabel
'n2';
Y2 = dft(y2,100); magY2=abs(Y2(1:1:26));
k2 = 0:1:25; w2 = 2*pi/100*k2;
subplot '224'; plot(w2/pi,magY2); title 'Magnituda Y2 iqbal';
xlabel 'frequency in pi unit';