A New Application of Lock In Amplifier-Adaptive Noise Canceller

This paper introduced an algorithm to track and eliminate the power line interference. The model of the algorithm came from the lock-in-amplifier (LIA) hardware circuit. Inheriting the LIA ´s excellency of inhibiting the noise, this algorithm could precisely detect the amplitude, frequency and phase of the interference signal in the corrupted ECG. This algorithm, which does not need to avoid the QRS complex, could track and eliminate interference signals ranging from 48 Hz-52 Hz. We made two experiments to test the performance of the algorithm. The first test data came from MIT-BIH, which had been corrupted by artificial interference signals. The second test data was the actual ECG signal. Both the results proved to be satisfactory.