DESIGN OF A TWO-CHANNEL QUADRATURE MIRROR FILTER BANK IN THE FREQUENCY DOMAIN

Abstract

QMF banks have received much attention since they can be successfully used to constitute a multirate signal processing system for splitting a signal into subbands and allowing the resynthesis of the signal from the subbands. In this dissertation, an iterative method for the design of two-band quadrature mirror-image filter banks proposed by Chen and Lee [6] is examined.- The method is then extended to the simulation of two-channel QMF bank. The quadrature mirror structure of QMF banks lead to the complete cancellation of interband aliasing due to the overlapping filter responses. If the filters involved have symmetric impulse responses of finite duration (FIR filter), no phase distortion will occur and hence the design is focussed on selecting filter parameters. This dissertation considers the design of QMF banks whose analysis and synthesis filters have linear phase. Due to the fact that the design problem in the frequency domain is a highly nonlinear optimization problem, we . follow a linearization technique,. proposed by [6]. According to this technique, the core work in finding the optimal filter coefficients at each iteration is to solve a set of linear equations. Alongwith, a two-channel QMF bank is simulated on the basis of designed low-pass analysis filter. Various signals are given at input of this bank. The corresponding reconstructed signals are obtained at output and reconstruction error have been computed. Also, spectra of the signals at each stage of this bank have been evaluated.