| The photoplethysmography signal has reflected human body importantinformation, which contains rich microcycle physiology pathology information, itis we study the human body circulatory system important information origin. Theapplication domain also develops the respiratory system from the human bodycirculatory system, In the human body blood pressure, the blood stream, the bloodoxygen, the brain oxygen, the myo- oxygen, the blood sugar microcycle, thecircumference blood vessel arteries rate, the breathing rate and the breath capacityand so on non-invasive measurement all to have the very goodapplication prospect.In pulse wave signal extraction process, it inevitably combines each kind ofnoise jamming, mainly is including the power frequency disturbance, the sensornoise, the myo-electrical noise, the baseline drifting, the electromagnetismequipment disturbance and so on. Before the further analysis to the signal, it needsto extract the effective pulse wave signal and restore the primitive profile from thestrong noise the pulse wave signal, then it can separate the signal from the noise.First this paper takes use of the multi-resolution of wavelet to eliminate thebaseline drifting causing by breathe and Shifting. Then through the threshold valuedenoising law, removes the noise which causes by the hardware equipment, in thefoundation, it can achieve the characteristic parameter of thephotoplethysmography through the method of the differential threshold value, thenit can computate human oxygen saturation.This paper totally includes six chapters. The contents of the paper are asfollows:The first chapter presents the measuring method of the photoplethysmography,and then analysis the significance, and the current research state, the chapter also analysis theapplication of photoplethysmography in human oxygen saturation, at last the chapter presentthe major research content of the subject.The second chapter presents the production principle ofphotoplethysmography and in the foundation introduces the measuring principle ofthe human oxygen saturation. First introduces the production principle of thephotoplethysmography, the characteristic of the photoplethysmography, theintroduces the application of the photoplethysmography in human oxygensaturation, and introduces the concept of human oxygen saturation and itsmeasuring technique. Finally summarizes the hardware of photoplethysmography. The third chapter introduces the theory part of the wavelet. First itintroduces the development history of the wavelet, then introduces the definition as well asthe characteristic of wavelet from the aspect of the separate wavelet, the continual wavelet andthe binary wavelet. Finally introduces the multi-resolution analysis and the Mallat algorithmbriefly.The fourth chapter introduces the denoising of thephotoplethysmography. First it introduces the characteristic of the noise under thewavelet decomposition, as well as the noise characteristic of thephotoplethysmography. Then it carries on the denoising processing of thephotoplethysmography. First step it carries on erasing baseline drifting caused bybreathing and body dislocation, it takes use of wavelet multi-resolution analysis todecompose the photoplethysmography, decomposing to the seventh criterion., itcan be seen from the simulation that the drifting signal can separate form thesignal. It carries on the restructure of the signal expect the drifting signal, then itcan obtain the signal that eliminate the drifting signal. The second step itintroduces the theory knowledge of the wavelet threshold value denoising, then itadopts three methods to carry on threshold value denoising: the compulsiondenoising method, the default threshold value denoising method, assigns thethreshold value denoising method, it explains the deficiencies of the first two kinds,it specifies how to take use of assigns the threshold value to carry on thetransforms various criteria in the wavelet in the denoising process. Then it canobtain the consistent estimate of the real signal from the signal with noise. Finallyit can achieve the most superior effect of elimination noise. The chapter simulatesthe partial algorithms, explains each kind of method according the characteristic ofthe photoplethysmographyThe fifth chapter calculates characteristic parameter of thephotoplethysmography using the differential threshold value method: arteries rateand peak - peak value, and it calculates degree of the human oxygen saturation. Atlast it presents the measurement result ,also analysis the result.The sixth chapter generalizes the major work of this paper, and also puts up somequestions which should be researched continuously in the future. |
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