A Method for Determining the Parameters in Ensemble Averaging of Frequency Spectrum of Surface Electromyogram using Breakpoint

Abstract

An ensemble averaging of frequency spectrum of biosignal corresponds to a smoothing of frequency spectrum obtained by Fourier transform of entire signal. As a general rule, a variation of frequency spectrum obtained by an ensemble averaging of signals becomes small, therefore, a spectrum becomes smooth by an increasing of segment number. On the other hand, a decrease of number of data per segment under dividing signals into a plurality of segments decreases a frequency resolution. Therefore, an ensemble averaging which is balanced between spectrum smoothness and frequency resolution is desirable. However, there is no definite method to determine both a segment number and a segment overlap ratio, which are parameters in ensemble averaging of frequency spectrum. In this study, we propose a method to determine these two parameters in surface electromyogram using breakpoint. Also, we present experimental results that were applied our method to surface electromyogram.