[Arithmetic for subtracting power line interference based on estimating sinusoidal parameters].

Electrocardiogram (ECG) signals are often contaminated by residual power-line interference. In order to filter the noise and not to distort signal too much, certain types of digital notch filters need a narrow frequency band, but such a band leads to ineffective filtering in the case of frequency deviation of the interference. In this paper, we propose a novel arithmetic. Firstly, sinusoidal parameters (frequency and phase) are estimated from the sinusoidal values in the linear segment of ECG. Secondly, a sinusoid function in linear segment is determined by the estimated sinusoidal parameters. Thirdly, the interference values in the nonlinear segment closest to the linear segment are calculated by the sinusoid function. Lastly, we subtract the corresponding interference value from the real value. The experiment results show that, in comparison with other arithmetic, the novel arithmetic can more effectively remove the power-line interference from ECG signal.