i'm trying to get an FFT of a signal
my FFT has 1024 samples
i added two sin functions one of freq 86,13Hz (2*44100/1024) and one of freq 129,19Hz (3*44100/1024)
the WAV looks like that (for 1 period) :
i then use this code to inspect the FFT
FFTSize = 1024; Y = wavread('2sins.wav'); current_window = zeros(FFTSize, 1); for k = 1:length(Y)/(FFTSize) for m = 1:FFTSize current_window(m, 1) = Y((k-1)*(FFTSize)+m, 1); end; plot(current_window) a = abs(Ydft); p = angle(Ydft); end;
the bins 2 and 3 have the maximum amplitude of 256 which is right as i used two sin of frequency 2 and 3
but when i look at the phases they are -pi/2 which is weird as they should be 0 no ?
here are the phases :
so you see they are -pi/2, why is that ?
and here is the WAV file i used so you can try yourself: http://www.khaelis.com/tmp/2sins.zip
thanks for help