close all
clear all
clc
fs = 1000;
T = 1;
t = 0:1/fs:T-1/fs;
x = chirp(t,20,1,220);
x=x';
a = 1;
sign = [];
final = [];

windowtime = 1/10*length(t);
b = windowtime;
iter = ((T*1000/windowtime)*2)-1;
w=hann(windowtime);

for o = 1 : iter
    for n = 1 : windowtime
        y = x(a:b);
        sign = y .*w;
        sign = fft(sign);
        sign = abs(sign);
        sign = sign(1:length(sign)/2);
    end
    final=[final,sign];
    a=a+windowtime/2;
    b=b+windowtime/2;
end
final= [final, final(:,end)];
f=linspace(0, fs/2, length(sign));
x=linspace(0, t(end), size(final,2));

figure (1)
surf(x,f,final)
view(2)
xlabel('Time [s]')
ylabel('Frequency [Hz]')