Power Line Interference Removal From Short-Latency Evoked Potentials Using Digital Time-Efficient Selective Elliptic Notch Filter

In this article, a concept of digital time-efficient IIR elliptic notch filters with a reduced transient response is presented. The proposed notch filter is designed to effectively suppress power line interferences from short-latency evoked potentials. Desired time-domain properties of the considered filter have been achieved through a time-varying stopband width and nonzero initial values of the filter. The designed filter has been verified with the use of the brainstem auditory evoked potential (BAEP) corrupted by the power line noise. The results of simulations and performance indices prove that the proposed parameter-varying elliptic notch filter with nonzero initial values is definitely more effective in removing the power line interference than commonly used time-invariant filters with zero initial values.