A Cascaded SSCF-IIR Adaptive Notch Filter

IIR adaptive notch filter (ANF) with allpass filter has many advantages such as reduction in filter order and realization of flat in-band characteristics compared to ANF using adaptive transversal filter. However, the removal performance of ANF deteriorates due to the influence of the colored noise included in the input signal. In this paper we propose a cascaded IIR ANF that is not affected by colored noise. The cost function of this ANF is the square sum of correlation function of the input and output signal with the decorrelation parameter not the square sum of conventional output error. We proved that the adaptive weights of the second order IIR ANF converge near the optimum value even if the number of sine waves of the input was unknown. The numerical verifications of the convergence performance compared to the conventional LMS-IIR ANF are also presented.