Komorowski Dariusz, Pietraszek Stanislaw
Faculty of Biomedical Engineering, Department of Biosensors and Biomedical Signals Processing, Silesian University of Technology, 40 Roosevelt'a street, 44-800, Zabrze, Poland.
Institute of Electronics, Division of Biomedical Electronics, Silesian University of Technology, 16 Akademicka street, 44-100, Gliwice, Poland.
J Med Syst. 2016 Jan;40(1):10. doi: 10.1007/s10916-015-0358-4. Epub 2015 Oct 29.
This paper presents the analysis of multi-channel electrogastrographic (EGG) signals using the continuous wavelet transform based on the fast Fourier transform (CWTFT). The EGG analysis was based on the determination of the several signal parameters such as dominant frequency (DF), dominant power (DP) and index of normogastria (NI). The use of continuous wavelet transform (CWT) allows for better visible localization of the frequency components in the analyzed signals, than commonly used short-time Fourier transform (STFT). Such an analysis is possible by means of a variable width window, which corresponds to the scale time of observation (analysis). Wavelet analysis allows using long time windows when we need more precise low-frequency information, and shorter when we need high frequency information. Since the classic CWT transform requires considerable computing power and time, especially while applying it to the analysis of long signals, the authors used the CWT analysis based on the fast Fourier transform (FFT). The CWT was obtained using properties of the circular convolution to improve the speed of calculation. This method allows to obtain results for relatively long records of EGG in a fairly short time, much faster than using the classical methods based on running spectrum analysis (RSA). In this study authors indicate the possibility of a parametric analysis of EGG signals using continuous wavelet transform which is the completely new solution. The results obtained with the described method are shown in the example of an analysis of four-channel EGG recordings, performed for a non-caloric meal.
本文介绍了基于快速傅里叶变换(CWTFT)的连续小波变换对多通道胃电图(EGG)信号进行的分析。EGG分析基于对几个信号参数的测定,如主频(DF)、主功率(DP)和胃电正常指数(NI)。与常用的短时傅里叶变换(STFT)相比,连续小波变换(CWT)的使用能使分析信号中的频率成分定位更清晰可见。这种分析通过一个可变宽度的窗口来实现,该窗口对应于观测(分析)的尺度时间。当我们需要更精确的低频信息时,小波分析允许使用长时间窗口;而当需要高频信息时,则使用较短的窗口。由于经典的CWT变换需要相当大的计算能力和时间,特别是将其应用于长信号分析时,作者使用了基于快速傅里叶变换(FFT)的CWT分析。通过利用循环卷积的特性获得CWT,以提高计算速度。该方法能够在相当短的时间内获得相对较长的EGG记录结果,比使用基于运行频谱分析(RSA)的经典方法要快得多。在本研究中,作者指出了使用连续小波变换对EGG信号进行参数分析的可能性,这是一种全新的解决方案。用所描述的方法获得的结果在对一顿无热量餐进行的四通道EGG记录分析示例中展示。