Apply wavelet transform to analyse EEG signal

A new processing system for analysing the EEG signal is proposed. The use of the wavelet transform as an effective mathematical analysis tool is described in this system. The basis idea of the wavelet transform is using a set of functions to express or approach a signal or a function. This function set is composed of a shifted and dilated mother wavelet. By means of various coefficients, the original signal can be described. The authors' analysis system contains two parts including hardware and software. The software is a windows applied program which provides an easy-to-learn, user-friendly graphical interface. The hardware includes an EEG amplifer, an A/D card, a microcomputer and a printer. The EEG signals obtained from 31 patients were analyzed using the wavelet transform method in this study. The authors can see from clinical applications that various states of the EEG signal correspond to a different representation of information in each scale. In other words, the features of the waveform in each scale using the wavelet transform can reflect the states of the EEG signal.