I'm studying what I believe to be a system that produces a (noisy) quantal response (i.e. there should be a minimum increment of response). To do this, I've plotted a histogram of some ~6000 amplitude values from the system into small bins, and performed an FFT on the histogram, expecting that a common quantal value should appear as the lowest frequency "spike". However, my spectral response: looks odd to me. What I see are what look like harmonics.
Why does this occur in the quantal release problem? Is this lowest frequency actually my quantal response, or is it a typical electrical response/artefact from the FFT of a signal with so many discontinuities? I thought that odd-numbered harmonics are the most powerful, but here they seem to be linearly declining. Why am I seeing other smaller spikes appear 1/3rd of the way through each of the "main" harmonic bands?