clear all; close all;
Fs=8000; F1=250; N=5; 
sigLen=Fs*N;
spY=30000;
subplot(2,3,1);
mysig=[];
myperiod=[ones(1,Fs/F1/2) -ones(1,Fs/F1/2)];
for idx=1:(F1*N); mysig=[mysig myperiod]; end
stem(mysig);
ylim([-2,2]); xlim([0,200]);
title(sprintf('%dHz pravouhly signal',F1));
subplot(2,3,2);
mySp=fft(mysig); myAbs=abs(mySp); 
stem (myAbs); xlim([0,sigLen]); ylim([-spY,spY]);
subplot(2,3,3);
stem (angle(mySp)); xlim([0,sigLen]); ylim([-2*pi,2*pi]);
subplot(2,3,5); 
stem (myAbs); xlim([0,sigLen]); ylim([-spY,spY]);
subplot(2,3,6)
randphase = 2*pi.*rand(1,sigLen)-pi; 
stem(randphase); xlim([0,sigLen]); ylim([-2*pi,2*pi]);
subplot(2,3,4);
mySp2=myAbs.*exp(i*randphase);
mysigA=real(ifft(mySp2));
stem(mysigA); ylim([-2,2]); xlim([0,200]);
title(sprintf('%dHz pravouhly signal s nahodou fazou',F1));
print(gcf,'randomPhase.png','-dpng'); 
sound(mysig, Fs); display("hram orig. 250Hz signal, stlac klavesu"); pause;
sound(mysigA, Fs); display("hram 250Hz signal s nahodnou fazou");