| ECG is the general reflection of heart's electric activity on body surface. The purpose of ECG process is to conclude the state of cardiovascular system according to the feature of ECG and make auxiliary decision .The study work of this paper is about ECG and can be divided into the following three parts:(1)A simple and fast real-time R-wave detection algorithm based on the modified difference threshold method is proposed after studying many present QRS detection methods. The principle of the algorithm is to calculate the quadratic sum of the first order difference of ECG and the second order difference of ECG in order to enhance the weight of QRS complex and suppress all kinds of noises. We choose the original ECG text, the noised ECG and the data from the MIT database to test our algorithm and the result indicates that our algorithm can suppress the noise to a great extent and localize the position of R-wave precisely.(2) Analysis of the intervals of the consecutive R-wave (HRV)is a non-invasive access to the study the function of automatic nervous system .After we have studied many HRV analysis methods ,we choose some typical data analysis methods and parameters suited for the short-term HRV as follows: a, the time-domain parameters AHR and r-MSSD. b . the frequency-domain parameters TP, LFnorm, HFnorm and LF/HF.c, the non-linear dynamic parameters FD, ApEn and TL to analyze the HRV of 10 healthy young man in the certain sleep stages :NREM4 stage and REM stage. We get the conclusion that the parameters gotten from the NREM4 stage are significantly smaller than that from REM stage. It is inferred that ,compared with the NREM4 stage, in the REM stage the complexity of cardiovascular system is much higher and the regulatory mechanism is more complicated. The result we get is in accordancewith the former physiology experiments.(3) The singularity always carries important feature information of signal. First, we have proven the theorem which describes the relation between the maximum of mode of wavelet transform and the singularity parameter-Lipschitzexponent: |Tψ(a, b)|b=t0 ≤ Caα(t0)+1/2), α(t0) represents Lipschitz exponent and |Tψ(a,b)|b=(t0) represents the maximum of mode of wavelet transform ,then wepropose and implement a computing algorithm of Lipschitz exponent in MATLAB. At last, we use this algorithm to analyze the R-wave of healthy persons as well as the arrhythmic patients and get the conclude that the singularity of healthy persons is significantly higher than that of arrhythmic patients. It is concluded that the cut down of singularity is resulted from the degraded complexity and regulatory ability of cardiovascular system. Through calculating Lipschitz exponent ,we provide a index to quantize the singularity of R-wave which gives a new idea of computerization of ECG analysis.The main contents of this paper is R-wave detection , the HRV analysis and the analysis of the singularity of R-wave. In addition, we also implement two ECG data acquisition systems based on sound card and USB6009 data acquisition card. After comparison of the two systems, we find the first system has some matching demand of data source and the sample rate is in the range of four given items, so the practical value is limited. However, the system based on USB6009 data acquisition card can achieve the goal of multi-channel, high speed real-time acquisition,display and save, so it is of wide use and can be used to build convenient data acquisition platform. And it can provide a good data source for the study and analysis in Lab. |
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