%spectrogram(x,window,noverlap,fs)
clear all,clc
fs=1e3,;%czestotliwość próbkowania
T_of_S=1; %czas trwania w sekundach
t=0:1/fs:T_of_S;%wektor czasu
x=chirp(t,20,T_of_S,200);%analizowany_sygnał
lw=0.25;%dlugosc okna w sek
lw_samp=lw*fs;%dlugosc okna w probkach
nakladowanie=0;% podane w %
noverlap=nakladowanie/100*lw_samp; %liczba probek podlegajacych nakladkowaniu
nfft=2^nextpow2(lw_samp);
temp=0;
i=1;
range=lw_samp;
j=range;
s_left=length(x);
max=length(x);
row=1;S=0;
while s_left>=range
    sig_temp=x(i:j-1);
    s_left=length(x(j:max));
    i=j-noverlap;
    j=i+range;
    whan=hanning(length(sig_temp));
    fft_temp=fft(sig_temp'.*whan,nfft);
    NS = length(fft_temp);
    S=S./length(sig_temp);
    S2plot = abs(fft_temp);
    df= fs/NS;
    fv= 0:df:(fs-df);
    S2plotSS = S2plot(1:NS/2+1);
    S2plotSS(2:end) = 2* S2plotSS(2:end);
    fvSS=fv(1:NS/2+1);
    ztemp=S2plotSS;
    XX(:,row)=S2plotSS;
    for k=1:(lw_samp-noverlap+1)
        A(:,(row-1)*(lw_samp-noverlap)+k)=ztemp;
    end
    row=row+1;
end
A=A';
[F,T]=meshgrid(0:df:fs/2,1/fs:1/fs:length(x)/fs);
h=surface(F,T,A);
set(h,'EdgeColor','none')
axis('tight');
%axis([fvSS(1) fvSS(end) 0 (length(x)-lw_samp)/fs]);
axis([fvSS(1) fvSS(end) 0 length(x)/fs]);
xlabel('Hz'),ylabel('czas');