An Adaptive Algorithm for Canceling Power-Line Interference in Biopotential Measurement

Biopotential measurements are very important in clinical diagnosis. However, the signal amplitude of biopotenials is very small and there usually exists stray capacitance between the electrode leads (or the human body) and the power lines, biopotential measurements are easily contaminated by 60-Hz (or 50-Hz) power-line interference. Analog or digital notch filter has been the most popular technique used for power-line interference removal. However, the notch filter performs well only when the power frequency is kept exactly at the stop band of the notch filter. The adaptive filtering technique provides another promising approach, yet there needs another reference channel for interference recording. The price of signal measurement is thus increased. The authors present a simple LMS-style algorithm for canceling the power-line interference in biopotential measurement. No reference channel is needed for adaptive filtration in this proposed algorithm. Compared with another technique serving for the same purpose, the proposed algorithm can remove practical power-line interference more effectively, and can be a post-acquisition processing remedy for biosignals having corrupted by power-line interference.