Electro Encephalography Measurements Using Wavelet Based Signal Processing (Part 1)

DOI : http://dx.doi.org/10.13005/msri/050207

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Generally, EEG wave forms are recorded and observed for prolonged periods. The pathological findings are based on measurements of abnormal wave patterns which can appear once in a while. Wavelets is a useful technique of signal analysis which finds application for diagnosing EEG pathology. First, it is explained how Multi-resolution analysis is performed on wavelets to show up with a good match ato the clinical bands of Alpha, beta , delta and theta rhythms in addition to waves and spikes. The appropriate choice of a wavelet is explained and the method indicated. Two method of displaying of wavelet analysis results are illustrated, one of plotting the maximal scale coefficients plot versus time; another of plotting the scale intensities versus scale value at a time point chosen for good EEG activity using the line of maxima in the scalogram figure. Comparative studies of a patient?s records over a long period of observation can be easily made to assess the disease prognosis.

Stochastic signal; EEG Records; Photic stimulation; Fourier Transform; Wavelet Transform