为了实现电磁干扰环境下的心电信号监测, 提出了一种抗电磁干扰的心电信号监测系统。论文给出了输出光电流的计算公式, 分析了半波电压及插入损耗对系统灵敏度的影响。利用铌酸锂电光晶体搭建实验系统, 测试了5位健康志愿者的心电信号。应用提出的系统和电学心电信号采集系统分别测试了正常环境及电磁环境下志愿者的心电信号。测试结果表明: 在正常环境下, 本系统能获得与电学心电信号采集系统同样清晰的心电信号波形; 在电磁环境下, 本系统获得的心电信号优于电学心电信号采集系统。最后定量计算了两者的信噪比, 计算结果表明: 在电磁干扰下, 本系统的信噪比变化量为0.54 dB(V2)/0.49 dB(V4), 而电学心电信号采集系统的信噪比变化量为24.07 dB(V2)/16.75 dB(V4)。

In order to realize the ECG monitoring under electromagnetic interference environment, an anti-EMI ECG monitoring system based on the optical modulator was proposed in this paper. Firstly, the calculation formula of output photocurrent was discussed, and the influence of half wave voltage and insertion loss on the sensitivity was analyzed. Secondly, the Lithium Niobate (LiNbO3) electro-optic crystal was used to establish experimental setup, and measure the ECG signals of five health subjects. Then the proposed system and electrical ECG acquisition system were used to detect the ECG signals of subjects under both of normal and electromagnetic environments. The measurement results showed that the proposed system could obtain clear ECG signals as same as the electrical ECG acquisition system under normal circumstances, but under the electromagnetic environment, the proposed system could obtain better ECG signals than the electrical ECG acquisition system. Finally, the signal-to-noise ratio (SNR) of the two systems were calculated. The calculation results showed that the SNR change of the proposed system was 0.54 dB(V2)/0.49 dB(V4) under the electromagnetic interference, and the SNR change of electrical ECG signal acquisition system was 2407 dB(V2)/16.75 dB(V4). Therefore, the proposed wearable ECG monitoring system can accurately monitor the ECG under the electromagnetic environment.