A nonlinear digital filter for separating nonstationary waves from stationary waves of the EEG

A new nonlinear digital filter which separates nonstationary waves such as spikes from stationary background waves of the EEG is proposed. This filter is composed of a prediction filter and a simple nonlinear function, and separates the nonstationary waves by processing the prediction error with the nonlinear function. This filter aims at real-time analysis of EEG, hence the algorithm of this filter is deliberately kept very simple, and the parameters in it are set adaptively. Some examples of separating spikes from epileptic EEG data are shown.