Study Of ECG Pretreatment Algorithm Based On The Adaptive Filter And Wavelet Transform

The ECG is a non-stationary random signal, containing mainly frequencyinterference, baseline drift and EMG interference noise, it is more difficult todenoising. Commonly denoising methods include wavelet transform, digital filtermethod, morphological filters, and other methods, computational complexity is highor the filtered signal distortion.Adaptive filter method according to the results of the first time have access to thefilter parameters, adjust the filter parameters to adapt to the unknown signal and noiseor statistical properties change on real-time. Adaptive filter does not require a prioriknowledge of the input signal, suitable for low SNR signal denoising filter structure issimple, small amount of calculation, the higher real-time signal processing; criteriabased on the Least Mean Square(LMS), can output the minimum mean square error ofthe signal and the input signal equal to each other, which can effectively avoid signaldistortion denoising to maximize the retention characteristics of the ECG information.ECG denoising algorithm based on adaptive filter.This paper selects the dual-band cascaded notch filter to remove frequencyinterference and baseline drift, both of which belong to the multi-frequencymonochromatic interference. Dual-band cascaded notch filter can retain thesingle-frequency notch filter characteristics, which consists of two single-band notchfilter in series, and the parameter adjustment independent of each other. Dual-bandcascaded notch filter after two successive iterations, convergence stabilized, canremove the frequency interference and baseline drift effectively.ECG signal is a periodic signal, and the EMG interference is a high frequencybroadband signals, their spectral characteristics close to Gaussian white noise. In lightof the above characteristics, this paper uses adaptive signal splitter to complete theEMG interference filter. Denoising method of adaptive signal separator targeted use ofthe time delay structure, separation of the broadband signal and periodic signal,thereby remove the EMG interference effectively.The detection of mutations of the ECG signal is one of the important applicationsof the wavelet transform. Wavelet transform has good time-frequency analysisfeatures, the point of the transform coefficients modulo value or zero generallycorresponds to the signal mutations. Therefore, based on wavelet transform modulusmaxima method of ECG QRS complex detection algorithm research. First ECG signalfor the three-scale decomposition, in paragraphs2,3scale by finding the zero positioning of R wave, then the beginning and ending points of the QRS complexdetection.This algorithm is based on MATLAB software platform simulation andexperimental results show better ECG denoising algorithm based on adaptive filter toremove frequency interference, baseline drift and EMG interference, high signal tonoise ratio and lower mean square error; QRS recognition algorithm based on wavelettransform, the higher recognition rate up to98%.