Unit Extraction

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.