%hamming1.m
clc
clear all
close all
display('Running hamming1.m');
%

%window width parameter 0 <= p < 0.5
p=0.1;

%signal
t = 0:0.015:10 ;           % Time vector
x = sin(20*t);              % Signal

%rectangular window

N=length(t);
l=1:N;

for k=1:N
    rect(k) = 1;
    if k < p*N
        rect(k)=0;
    end;
    if k > (1-p)*N
        rect(k)=0;
    end;
end


%fft of rectangular window
fftrect=fftshift(fft(rect));
mrectdb=20*log(abs(fftrect));

f = (0:length(x)-1)/length(x)-0.5; % Frequency vector

figure;
subplot(2,1,1);
plot(t,rect); title('Rectangular window in time domain');
axis([0 10 0 2]);
subplot(2,1,2);
plot(f,mrectdb); title('Rectangular window in freq domain');
axis([-0.1 0.1 -50 150]);

display('rectangular window...hit return to continue');
pause;

%filter using rectangular window

%FFT of signal
%window the signal

for i=1:N
    x(i) = x(i)*rect(i);
end

%FFT
%fftx0 = fft(x);                       % Compute DFT of x
fftx=fftshift(fft(x));
mx = abs(fftx); px = unwrap(angle(fftx)); % Magnitude and phase
mxdb=20*log(mx);

%plot signal

figure;
subplot(2,1,1)
plot(t,x), title('signal*rectangle'), axis([0 10 -1 1]);
subplot(2,1,2)
plot(f,mxdb); title('signal*rectangle - frequencx domain (magnitude)'), axis([-0.5 0.5 -50 150]);

display('DFT using rectangular window...hit return to continue');
pause;

%hamming window

for k=1:N
    ham(k) = 0.54 -0.46*cos(2*pi*(k-p*N)/((1-2*p)*N-1));
    if k < p*N
        ham(k) = 0;
    end
    if k > (1-p)*N
        ham(k)=0;
    end;
end

%fft of hamming window
fftham=fftshift(fft(ham));
mhamdb=20*log(abs(fftham));

figure;
subplot(2,1,1);
plot(t,ham); title('Hamming window in time domain');
axis([0 10 0 2]);
subplot(2,1,2);
plot(f,mhamdb); title('Hamming window in freq domain');
axis([-0.1 0.1 -50 150]);

display('Hamming window...hit return to continue');
pause;

%filter using hamming window

%window the signal

for i=1:N
    xh(i) = x(i)*ham(i);
end

fftxh0 = fft(xh);                       % Compute DFT of xh
fftxh=fftshift(fftxh0);
mxh = abs(fftxh); pxh = unwrap(angle(fftxh)); % Magnitude and phase

mxhdb=20*log(mxh);


%plot ham windowed signal

figure;
subplot(2,1,1)
plot(t,xh), title('signal*hamming'), axis([0 10 -1 1]);
subplot(2,1,2)
plot(f,mxhdb); title('signal*hamming - frequencx domain (magnitude)'), axis([-0.5 0.5 -50 150]);

display('DFT using Hamming window...');
display('...done');