Hi Mustafa,
Since in your case you are doing a cross-correlation between a signal and its own shifted version, to simplify things, you would just need to ensure that the signal and its shifted version have the same scaling. To ensure this, you can use something like:
% s1 = some signal
% s2 = time shifted s1
s1 = s1/max(abs(s1));
s2 = s2/max(abs(s2));
scorr = xcorr(s1,s2);
Hope this helps,
Cheers!
Abhiram
