Unit extraction is carried out using MATLAB functions. The procedure
is to produce a time series from the raw signal by applying a Fast
Fourier transform to slices of the data and representing that slice by
the sum of squares of the Fourier Coefficients. The slices are
1000-points long, representing 0.05 seconds each.
A threshold is applied to the time series and an algorithm sweeps
through from start to finish; 4 values above the threshold indicate
the start of a unit, 2 values below indicate the space between units.