I want to characterize a binary time-series signal x (derived from neuron action potential data) in the frequency domain.
Should I use the FFT of the original signal x, or the power spectrum (FFT of the autocorrelation of x, which is defined as $k(n)=E[x(t)\cdot x(t-n)]$ )?
Also, does anyone know any literature which explicitly talks about this, or at least took sides?