Adaptive noise canceling applied to sinusoidal interferences

TLDR

Sinusoidal interference is usually removed by measuring its frequency and applying a notch filter. This study investigates a new method to eliminate sinusoidal or periodic interference from signals. The method uses an auxiliary reference input containing the interference, filters it to match the sinusoid, and subtracts it from the primary signal, thereby implementing an adaptive noise canceling notch filter. Experiments demonstrate that the adaptive filter converges to a time‑varying solution that implements a tunable notch filter at each reference frequency, offering a simple alternative for tracking and eliminating sinusoidal interferences.

Abstract

This paper investigates a new method for eliminating sinusoidal or other periodic interference corrupting a signal. This task is typically accomplished by explicitly measuring the frequency of the interference and implementing a notch filter at that frequency. The method proposed herein uses an adaptive filter to eliminate the interference. The procedure is called adaptive noise canceling and is applicable when an auxiliary reference input is available containing the interference alone. The reference input is filtered in such a way that it closely matches the interfering sinusoid, and is then subtracted from the primary input leaving the signal alone. The results of this research show that when a sum of sinusoids is applied to an adaptive filter, the filter converges to a dynamic solution in which the weights of the filter are time varying. This time-varying solution implements a tunable notch filter, with a notch located at each of the reference frequencies. When used in noise-canceling applications, this adaptive notch filter provides a simple alternative to other methods of tracking and eliminating sinusoidal interferences.