Comparison of single-level and multi-level filtering systems of EEG signal

The paper presents a method of frequency response comparison of single-level and multi-level EEG filtering systems. The problem is not trivial since internal structures of the systems are different and cannot be compared directly. It has been shown how the multi-level system can be reduced to its single-level equivalent, which makes the two types of systems directly comparable. Next, some amplitude and phase distortion measures have been defined and used to evaluate two EEG filtering systems based on Butterworth IIR filters.