Sadasivan P K, Dutt D N
Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, India.
Med Biol Eng Comput. 1995 May;33(3):306-12. doi: 10.1007/BF02510504.
One of the main disturbances in EEG signals is EMG artefacts generated by muscle movements. In the paper, the use of a linear phase FIR digital low-pass filter with finite wordlength precision coefficients is proposed, designed using the compensation procedure, to minimise EMG artefacts in contaminated EEG signals. To make the filtering more effective, different structures are used, i.e. cascading, twicing and sharpening (apart from simple low-pass filtering) of the designed FIR filter. Modifications are proposed to twicing and sharpening structures to regain the linear phase characteristics that are lost in conventional twicing and sharpening operations. The efficacy of all these transformed filters in minimising EMG artefacts is studied, using SNR improvements as a performance measure for simulated signals. Time plots of the signals are also compared. Studies show that the modified sharpening structure is superior in performance to all other proposed methods. These algorithms have also been applied to real or recorded EMG-contaminated EEG signal. Comparison of time plots, and also the output SNR, show that the proposed modified sharpened structure works better in minimising EMG artefacts compared with other methods considered.
脑电图（EEG）信号中的主要干扰之一是肌肉运动产生的肌电图（EMG）伪迹。本文提出使用具有有限字长精度系数的线性相位FIR数字低通滤波器，该滤波器通过补偿程序进行设计，以最小化受污染EEG信号中的EMG伪迹。为了使滤波更有效，采用了不同的结构，即对设计的FIR滤波器进行级联、加倍和锐化（除了简单的低通滤波）。针对加倍和锐化结构提出了改进方法，以恢复在传统加倍和锐化操作中丢失的线性相位特性。使用信噪比（SNR）的改善作为模拟信号的性能指标，研究了所有这些变换滤波器在最小化EMG伪迹方面的功效。还比较了信号的时间图。研究表明，改进后的锐化结构在性能上优于所有其他提出的方法。这些算法也已应用于真实的或记录的受EMG污染的EEG信号。时间图的比较以及输出SNR表明，与其他考虑的方法相比，所提出的改进锐化结构在最小化EMG伪迹方面效果更好。
