Chourasia V S, Mittra A K
Electronics Engineering Department, MIET, Gondia, MS, India.
J Med Eng Technol. 2009;33(6):442-8. doi: 10.1080/03091900902952618.
This paper is aimed at the selection of suitable mother wavelet and denoising algorithm for the analysis of foetal phonocardiographic (fPCG) signals. Fourier based analysing tools have some limitations concerning frequency and time resolutions. Although wavelet transform (WT) overcomes these limitations, it requires proper selection of a mother wavelet and denoising algorithm. In this study a suitable mother wavelet is selected on the basis of properties of different wavelet families and characteristics of the fPCG signals. The universal threshold, minimax threshold and rigorous SURE threshold algorithms along with soft or hard thresholding rule have been compared to denoise these signals. The mean squared error (MSE) is used to evaluate the performance of these algorithms. The results show that the fourth order Coiflets wavelet has a better performance for the analysis of fPCG signals when using the rigorous SURE threshold denoising algorithm with soft thresholding rule. The proposed approach is simple and proves to be effective when applied to the selection of suitable mother wavelet and denoising algorithm for the fPCG signals. These denoised signals can be used for the accurate determination of foetal heart rate (FHR) and further diagnostic applications of the foetus.
本文旨在为胎儿心音图（fPCG）信号分析选择合适的母小波和去噪算法。基于傅里叶的分析工具在频率和时间分辨率方面存在一些局限性。尽管小波变换（WT）克服了这些局限性，但它需要正确选择母小波和去噪算法。在本研究中，根据不同小波族的特性和fPCG信号的特征选择合适的母小波。对通用阈值、极小极大阈值和严格的SURE阈值算法以及软阈值或硬阈值规则进行了比较，以对这些信号进行去噪。均方误差（MSE）用于评估这些算法的性能。结果表明，当使用具有软阈值规则的严格SURE阈值去噪算法时，四阶Coiflets小波在fPCG信号分析中具有更好的性能。所提出的方法简单，并且在应用于为fPCG信号选择合适的母小波和去噪算法时被证明是有效的。这些去噪后的信号可用于准确测定胎儿心率（FHR）以及胎儿的进一步诊断应用。
