Multiresolution Analysis Based Denoising Algorithm for
Dynamic Esophageal pH Monitoring Signal
Wang Lei Zheng Chongxun Yuan Junfeng Song Lei
(Biomedical Engineering Institute,Xi'an Jiaotong University, Xi'an 710 049)
Abstract A denoising algorithm for dynamic esoph ageal pH monitoring signal is first introduced in this paper. The algorithm was developed on the basis of multiresolution analysis. The pH monitoring signal was investigated in experiments, then the algorithm was formulated by multiresoluti on analysis based on discrete dyadic wavelet transform combining with the result s of the investigation mentioned above. Application of this algorithm to clinica l data processing has proved its satisfactory denoising effect.
Key words Dynamic esophageal pH monitoring Multiresol ution analysis Digital signal processing Denoising algorithm
1 监测信号噪声的来源
食道动态pH监测可作为判断胃食道返流的“金标准”［1］，监测系统借助 传感器和便携式记录器，对患者食道的pH进行长时间(如24 h)的动态监测，然后将记录器内 的数据传输至计算机进行分析。传感器由测量电极和参比电极组成，测量电极一般选用结构 简单、精度较高、成本低的锑电极。根据参比电极的不同可将传感器分为外参比式和内参比 式两种，前者的参比电极为体表贴片电极，在监测过程中贴于体表的合适位置(如胸骨柄处 体表)；后者则是将参比电极与测量电极集成在传感器导管上置于患者食道内，参比电极可 选用柔性Ag-AgCl电极管。在监测过程中会不可避免的引入如下几种噪声：
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