应用锁定放大原理去除脑电干扰

An Application of Lock-in Amplifier to Eliminate the Power Line Interference in EEG

介绍了一种新型的去除工频干扰的方法.算法的主要思想源于硬件电路中的锁定放大器,它能精确地检验出信号中工频干扰的幅度、频率和相位并重构出干扰信号,将原始信号减去重构出的干扰信号即能得到正确的低噪信号.算法继承了锁定放大器出色的抗干扰能力.用一段采样频率为200 Hz的单导联脑电(EEG)数据测试算法,在其中添加了幅度、频率和相位在一定范围随机变化的噪声信号,最终得到的还原波形与原波形基本一样.还原波形与污染波形相比,信噪比提高了约30 dB,取得了令人满意的效果.

This paper introduces a new type of power-line interference removal method, the main idea of the algorithm is derived from the lock-in amplifier in hardware circuit, which can accurately test the amphtude, frequency and phase of power-line interference in the signals, and gain the correct low-noise signal through subtracting the reconstructed interference signal from the original signal. This algorithm inherits the excellent anti-interference ability of lock-in amplifier. This algorithm has been tested in an experiment, in which we used a period of single-lead EEG data of 200 Hz sampling frequency. We added the data with noise signal whose amplitude, frequency and phase varied randomly in a certain range. The restored waveform we finally obtained is almost the same as the original waveform. And compared with the pollution waveform, SNR of the restored waveform improves about 30 dB. The results are satisfactory.