Pseudo-QMF bank design with controlled in-band aliasing

A new and simple method to design cosine-modulated filter banks with approximate reconstruction is presented in this paper. The new system is generated from a unique prototype filter with linear-phase Type I or Type II obtained through any conventional approach, without need for any later optimization to obtain its coefficients. Thus, the main advantage offered by this method is the facility to design the filter bank as a whole, since nonlinear optimization and spectral factorization are avoided. Other main features of the new approach are the elimination of phase distortion, an aliasing level comparable to the stopband gain of the prototype filter used for cosine-modulation and a very low-amplitude distortion in most of the spectrum. This paper contains also a closed expression for the overall distortion transfer function and proposes a new graphic method to evaluate amplitude distortion and aliasing. Several examples are included. (C) 2001 Elsevier Science B.V. All rights reserved.