Frequency-response masking approach for digital filter design:complexity reduction via masking filter factorization

摘要

It has been reported in several recent publications that thenfrequency response masking technique is eminently suitable fornsynthesizing filters with very narrow transition-width. The majornadvantages of the frequency response masking approach are that thenresulting filter has a very sparse coefficient vector and that thenresulting filter length is only slightly longer than that of thentheoretical (Remez) minimum. The system of filters produced by thenfrequency response masking technique consists of a sparse coefficientnfilter with periodic frequency response and one or more pairs of maskingnfilters. Each pair of the masking filters consist of two filters whosenfrequency responses are similar except at frequencies near thenband-edges. In this paper, we present three methods for reducing thencomplexity of the masking filters. The success of our technique is duento the fact that each pair of the masking filters can be realized as ancascade of a common subfilter and a pair of equalizers