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摘要: 為消除陡脈沖帶來的干擾,分析了陡脈沖干擾的特點,建立了陡脈沖噪聲數學模型,提出了基于變分模態分解(Variational mode decomposition, VMD)的心電信號濾波算法,提取疊加在心電信號中陡脈沖干擾分量、識別陡脈沖干擾分量并剔除陡脈沖干擾分量;為減少VMD分解層數、提高實時性并減少內存消耗,提出了心電信號預處理算法;針對醫療環境中的隨機噪聲伴隨陡脈沖出現的情況,分析了VMD后子信號中隨機噪聲的特點,提出了基于VMD子信號能量估計的閾值去噪算法;利用變分模態分解的帶通濾波器組特性,提出了基于變分模態分解子信號重組的QRS波群檢測算法,配合濾波算法以提高心電信號特征檢測精度。以添加了高斯白噪聲和模擬陡脈沖干擾的MIT?BIH數據庫心電信號和醫療環境中采集的心電信號為實驗對象,分別實現對濾波算法和QRS波群檢測算法的定量對比分析。
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關鍵詞:
- 心電信號 /
- 陡脈沖干擾 /
- 變分模態分解 /
- MIT?BIH數據庫 /
- QRS波群
Abstract: Applying a steep pulse voltage of appropriate amplitude to a cell membrane can induce transient and reversible breakdown of the membrane, which has broad application prospects in biomedicine and clinical fields. However, the noise generated by the steep pulse seriously interferes with a patient’s electrocardiogram (ECG) signal resulting in decrease in the accuracy of the ECG feature point detection algorithm. Thus, doctors are unable to understand the state of the patient during treatment, thus limiting complete benefits of the therapy. To eliminate the interference caused by the steep pulse, we analyzed the characteristics of steep pulse interference and established the mathematical model of steep pulse noise. Moreover, we proposed an ECG signal filtering algorithm based on variational mode decomposition (VMD) to extract the steep pulse interference component superimposed on the ECG signal. The proposed algorithm could identify and eliminate the steep pulse interference component. We also designed an ECG signal preprocessing algorithm to reduce the decomposition layer of the VMD algorithm, which improved the real-time performance and reduced the memory consumption. To identify the random noise in the medical environment accompanied by the occurrence of steep pulses, we analyzed the characteristics of random noise in the sub-signal after VMD. Further, we proposed a threshold denoising algorithm based on VMD for sub-signal energy estimation. On the basis of the characteristics of a band-pass filter bank with VMD, we proposed a QRS complex detection algorithm based on VMD sub-signal recombination. Combined with the filtering algorithm, the proposed algorithm was able to improve the accuracy of ECG signal detection. By conducting experiments on ECG signals from the MIT–BIH database with Gaussian white noise and simulated steep pulse interference and those collected in the medical environment, we compared and analyzed the filtering algorithm and QRS complex detection algorithm.-
Key words:
- ECG signal /
- steep pulse interference /
- variational mode decomposition /
- MIT?BIH database /
- QRS complex
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表 1 陡脈沖干擾消除效果對比
Table 1. Results obtained after a variety of filtering processes
SNR of the original signal/dB Bandpass filter(SNR)/dB Wavelet packet filter(SNR)/dB Algorithm of this paper(SNR)/dB 1.481 ?5.369 0.199 8.022 ?6.732 ?11.456 ?8.710 3.070 ?12.110 ?18.928 ?13.913 ?0.410 表 2 去噪效果對比
Table 2. Comparison of the results of the filtering processes
表 3 與常用算法準確度對比
Table 3. Comparison of the accuracy of the algorithms
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參考文獻
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