Adaptive comb filters for enhancement of quasi periodic signals

Adaptive comb filters (ACFs) have notches at multiples of the fundamental frequency. For the ACF proposed only one parameter is adapted for removal of harmonic components. The RML (recursive maximum-likelihood) algorithm used is much less complex than the existing ones. The ACF is implemented as cascaded second-order cells and only the parameter of the first cell is estimated. Depending on the energy of the fundamental frequency, convergence to a local minimum can be realized. Some strategy (penalty) can be implemented to avoid this problem. It can be shown that the proposed algorithm is globally stable provided that the debiasing parameter is appropriately chosen. No stability test is needed. If p is the number of harmonic components, only 12p multiplications and 10p additions are required for the RML estimation of ACF parameters