A comb filter with adaptive notch gain for periodic noise reduction

A comb filter is used to eliminate a periodic noise signal from an observed signal. For extracting the desired signal, one of the most important factors of the comb filter is the notch gain which controls an elimination quantity of the observed signal at noise frequencies. Conventional comb filters employ a predesigned notch gain under the assumption that the appropriate notch gain is known. Unfortunately, in many practical situations, the appropriate notch gain is unknown and often changes. In this paper, we propose a new comb filter with the adaptive notch gain to automatically achieve the appropriate notch gain. In the proposed method, we utilize an adaptive line enhancer (ALE) instead of the conventional notch gain multiplier. When the ALE completely estimates the periodic noise signal, the ALE's frequency response directly gives the appropriate notch gain. Simulation results show the effectiveness of the proposed adaptive comb filter.