%0 Journal Article
%T Two-Channel Quadrature Mirror Filter Bank: An Overview
%A S. K. Agrawal
%A O. P. Sahu
%J ISRN Signal Processing
%D 2013
%R 10.1155/2013/815619
%X During the last two decades, there has been substantial progress in multirate digital filters and filter banks. This includes the design of quadrature mirror filters (QMF). A two-channel QMF bank is extensively used in many signal processing fields such as subband coding of speech signal, image processing, antenna systems, design of wavelet bases, and biomedical engineering and in digital audio industry. Therefore, new efficient design techniques are being proposed by several authors in this area. This paper presents an overview of analysis and design techniques of the two-channel QMF bank. Application in the area of subband coding and future research trends are also discussed. 1. Introduction The concept of quadrature mirror filter (QMF) bank was first introduced by Croisier et al. [1] in 1976, and then Esteban and Galand [2] applied this filter bank in a voice coding scheme. QMF have been extensively used for splitting a signal into two or more subbands in the frequency domain, so that each subband signal can be processed in an independent manner and sufficient compression may be achieved. Eventually, at some point in the process, the subband signals are recombined so that the original signal is properly reconstructed [3]. These filters find applications in many signal processing fields, such as design of wavelet bases [4, 5], image compression [6, 7], digital transmultiplexers used in FDM/TDM conversion [8, 9], discrete multitone modulation systems [10], ECG signal compression [11, 12], antenna systems [13], digital audio industry [14], biomedical signal processing [15], equalization of wireless communication channels [16], and analog voice privacy systems [17], due to advancement in QMF bank. In comparison to earlier band pass filter based subband coding systems, the QMF bank based systems have many advantages as given next.(a)Aliasing distortion is eliminated in QMF bank based subband coding systems; therefore, the transition width of the filters is not much important. Lower order filters with wider transition band can be used [2].(b)Computation complexity is reduced in case of subband coding system based on QMF banks [2].(c)Lower bit rates are possible, without degrading the quality of decoded speech signals. (d)QMF based subband coders [18, 19] provide more natural sounding, pitch prediction, and wider bandwidth than earlier subband coders. Two-channel filter banks can be classified into three types: quadrature mirror filter banks, orthogonal filter banks, and biorthogonal filter banks [20]. These filter banks can be designed to have either the
%U http://www.hindawi.com/journals/isrn.signal.processing/2013/815619/