위전도 신호처리를 위한 웨이브렛 필터와 디지털 필터의 비교

Abstract

Electrlgastrography(EGG) is an noninvasive method for measuring gastric electrical activity on the abdomen resulting from muscle. EGG signals have a very low frequency range(0.0083~0.15㎐) and extremely low amplitude(10~100μV). consequently, EGG signals is easily influenced by other noises. Both finite impulse response(FIR) and infinite impulse response (IIR) filters need high orders or have phase distortions for passing very narrow bandwidth of the EGG signal. In this study, we decomposed EGG signals using a wavelet multiresolution method with Doubechies mother wavelet. The EGG signals were decomposed to seven levels. We reconstructed signal by summing the decomposed signals from level four to seven. To evaluate the performance of the wavelet multiresolution filter(WMF) with simulated EGG signal using two kinds of FIR and four kinds of IIR filters., we used two indices; signal to noise ratio(SNR) and reconstruction squared error(RSE). The SNR of WMF had 9.5, 6.9 and 4.7 dB bigger than that of the other filters at different noise levels, respectively. Also, The RSE of WMF had 1.22×106, and 1.22×106 smaller than that of the other filters at different noise levels, respectively. The WMF performed better in the SNR and RSE than two kinds of FIR and four kinds of IIR filters.