A frequency-domain LMS comb filter

A new application of the least mean squares algorithm (LMS) to signal analysis and enhancement is presented. The LMS is implemented in the frequency domain to simulate a fixed-notch filter that nulls sinusoids with harmonically related frequencies. In the proposed structure, the Fourier transform (FT) block length is set to represent the fundamental period of the undesired periodic signal. The paper shows that by applying constant deterministic signals to the reference input, the frequency-domain LMS adaptive structure operates on eliminating all constant values in the transform and, therefore, cancels all harmonic frequency components, leaving out other components in the signal to propagate to the error with minimum distortion