So I have been away from education for a little while now and I'm going through some refresher stuff - in particular I have been playing around with FFTs. If i take (with matlab notation): time = 0:0.01:10 y = fft(sin(2*pi*f*time)) with f = 5 then the maximum amplitude of the fft output is about 498. with f = 10 the maximum amplitude of fft output is 492. I understand the amplitude is 'halved' in both cases because this fft is ambiguous so the energy is spread over two peaks. But why is the energy less when the frequency increases? I have more cycles in the case with more frequency, but I suppose this means I have less samples. Also, is it usual to normalise this in some way? It seems like this is something you wouldn't want if you were dealing were plotting energy return from doppler shifts.