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Yong Ching Lim - One of the best experts on this subject based on the ideXlab platform.
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Improved weighted least squares algorithm for the design of Quadrature Mirror Filters
IEEE Transactions on Signal Processing, 1999Co-Authors: Chee-kiang Goh, Yong Ching LimAbstract:This paper presents an improved weighted least squares (WLS) algorithm for the design of Quadrature Mirror Filters (QMFs), First, a new term is incorporated into the objective function that effectively prevents an optimization algorithm from producing suboptimal QMFs. These suboptimal QMFs exhibit a transition band anomaly; the frequency responses of the Filters have large oscillatory components in the transition band. The new term can be applied to the WLS design of any FIR filter to prevent a similar transition band anomaly. Next, we present an algorithm to obtain the QMF coefficients that minimize the objective function incorporating the new term. The computational requirement of this algorithm is also briefly discussed. Last, we include a set of practical design rules for use with our algorithm. These rules simplify the design process by providing good estimation of the design parameters, such as the minimum filter length, to meet a given set of QMF specifications.
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an efficient algorithm to design perfect reconstruction regular Quadrature Mirror Filters using weighted l sub p error criteria
International Symposium on Circuits and Systems, 1998Co-Authors: Chee-kiang Goh, Yong Ching LimAbstract:An efficient iterative algorithm is presented in this paper to design lattice-type perfect reconstruction regular Quadrature Mirror Filters (PR-QMF) by minimizing the pth power of an appropriate error criteria, where p can be a function of /spl omega/. The filter bank design is approximated as an unconstrained weighted least squares problem with respect to the lattice coefficients. Typically, only a few iterations of our algorithm are needed to obtain an optimal solution in the weighted L/sub p/ sense. An estimation of the number of canonic signed digit (CSD) terms needed to quantize the lattice coefficients yielding minimal degradation of the filter's stopband attenuation is also derived. Efficient multiplierless implementation of lattice-type regular PR-QMF banks are easily obtained using this result.
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An efficient weighted L/sub p/ algorithm for the design of Quadrature Mirror Filters
IEEE Signal Processing Letters, 1997Co-Authors: Chee-kiang Goh, Yong Ching LimAbstract:We present an efficient weighted L/sub p/ algorithm for the design of Quadrature Mirror Filters. The filterbank design process is formulated as an iterative weighted least-squares optimization problem. Our algorithm minimizes the pth power of the error function, where p may vary in different frequency bands. Good designs are obtained, typically, in a few iterations.
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Novel efficient approach for the design of equiripple Quadrature Mirror Filters
IEE Proceedings - Vision Image and Signal Processing, 1994Co-Authors: R.-h. Yang, Yong Ching LimAbstract:Quadrature Mirror Filters have been used extensively in subband coding of speech signals. The authors introduce a novel efficient approach for the design of equiripple Quadrature Mirror Filters. The new approach is more efficient than the previously proposed design method in terms of computer time and memory requirement.
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The design of weighted minimax Quadrature Mirror Filters
IEEE Transactions on Signal Processing, 1993Co-Authors: Yong Ching Lim, R.-h. Yang, Soo Ngee KohAbstract:A technique for converting the constrained nonlinear optimization problem encountered in the design of weighted minimax Quadrature Mirror Filters into an iterative unconstrained nonlinear optimization problem is presented. This renders the design of weighted minimax Quadrature Mirror Filters possible. The technique is very efficient, typically taking about seven iterations to converge. A rapidly converging iterative procedure for solving the above nonlinear unconstrained optimization problem is also presented. This procedure typically requires less than five iterations to converge. >
Soo-chang Pei - One of the best experts on this subject based on the ideXlab platform.
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An iterative approach for minimax design of multidimensional Quadrature Mirror Filters
Signal Processing, 2011Co-Authors: Jong-jy Shyu, Soo-chang Pei, Yun-da HuangAbstract:In this paper, a nest of iterative techniques is proposed for the minimax design of Quadrature Mirror filter (QMF) banks. The method can be generalized such that multidimensional QMF banks can be designed by the proposed algorithm. For a given weighting function, an iterative method is used to minimize the objective error function in the inner iterations. To further reduce the peak error of overall magnitude response, an iterative weighting-updated technique is adopted in the outer iterations. Comparing with the existing works concern the design of perfect-reconstruction QMF banks, only one of the Filters is needed to be designed under the cost of magnitude distortion, but the system complexity can be reduced drastically. Several examples, including design of 2-D and 3-D QMF banks, will be presented to demonstrate the effectiveness of the proposed method.
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A class of efficient recursive Quadrature Mirror Filters for subband coding
IEEE Transactions on Signal Processing, 1991Co-Authors: Soo-chang Pei, Sy-been JawAbstract:A class of recursive Quadrature Mirror Filters (QMFs) of the form H(Z)=N(Z)/D(Z/sup 2/) is proposed for subband coding. These Filters can be efficiently designed with the iterative Remez exchange algorithm. Simple modifications are made to the Pei (see IEEE Trans. Circuits Syst., vol.CAS-36, no.2, p.311, 1989), Liang, McClellan, and Parks computer program for designing these recursive QMF Filters efficiently. The resulting Filters totally eliminate the aliasing terms and can achieve almost perfect magnitude reconstruction, with -131.5-dB distortion. A design example is presented to show the effectiveness of this approach. >
D Esteban - One of the best experts on this subject based on the ideXlab platform.
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ICASSP - Design and evaluation of parallel Quadrature Mirror Filters (PQMF)
ICASSP '83. IEEE International Conference on Acoustics Speech and Signal Processing, 1Co-Authors: Claude Galand, D EstebanAbstract:Quadrature Mirror Filters (QMF) have been proposed in /1/, and are now widely used in digital sub-band coding of speech. The standard approach to the QMF splitting/reconstruction of a signal is based on a tree arrangement of half-band QMF Filters. In this paper, we show that, assuming a proper design, a parallel implementation of the QMF filter bank (PQMF) is much more efficient than the tree implementation. In the first part of the paper, the basic tree approach is briefly reviewed. Than the parallel filter bank structure is introduced, the equations for alias-free reconstruction are derived and solved. It is shown that the parallel approach can drastically be simplified by truncating the so computed impulse responses. The effects of this truncation have been experimentally evaluated and some rules of thumb have been established for optimum truncation order. An example of design is given to illustrate the proposed method.
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Application of Quadrature Mirror Filters to split band voice coding schemes
ICASSP '77. IEEE International Conference on Acoustics Speech and Signal Processing, 1Co-Authors: D Esteban, C. GalandAbstract:This paper deals with applications of Quadrature Mirror Filters (QMF) to coding of voice signal in sub-bands. Use of QMF's enables to avoid the aliasing effects due to samples decimation when signal is split into sub-bands. Each sub-band is then coded independently with use of Block Companded PCM (BCPCM) quantizers. Then a variable number of bits is allocated to each sub-band quantizer in order to take advantage of the relative perceptual effect of the quantizing error. The paper is organized as follows: - First, splitting in two sub-bands with QMF's is analysed. -Then, a general description of a splitband voice coding scheme using QMF's is made. -Finally, two coding schemes are considered, operating respectively at 16 KBps and 32 KBps. Averaged values of S/N performances are given when encoding both male and female voices. Comparisons are made with conventional BCPCM and CCITT A-Law. Taped results will be played at the conference.
Sy-been Jaw - One of the best experts on this subject based on the ideXlab platform.
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A class of efficient recursive Quadrature Mirror Filters for subband coding
IEEE Transactions on Signal Processing, 1991Co-Authors: Soo-chang Pei, Sy-been JawAbstract:A class of recursive Quadrature Mirror Filters (QMFs) of the form H(Z)=N(Z)/D(Z/sup 2/) is proposed for subband coding. These Filters can be efficiently designed with the iterative Remez exchange algorithm. Simple modifications are made to the Pei (see IEEE Trans. Circuits Syst., vol.CAS-36, no.2, p.311, 1989), Liang, McClellan, and Parks computer program for designing these recursive QMF Filters efficiently. The resulting Filters totally eliminate the aliasing terms and can achieve almost perfect magnitude reconstruction, with -131.5-dB distortion. A design example is presented to show the effectiveness of this approach. >
Soo Ngee Koh - One of the best experts on this subject based on the ideXlab platform.
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The design of weighted minimax Quadrature Mirror Filters
IEEE Transactions on Signal Processing, 1993Co-Authors: Yong Ching Lim, R.-h. Yang, Soo Ngee KohAbstract:A technique for converting the constrained nonlinear optimization problem encountered in the design of weighted minimax Quadrature Mirror Filters into an iterative unconstrained nonlinear optimization problem is presented. This renders the design of weighted minimax Quadrature Mirror Filters possible. The technique is very efficient, typically taking about seven iterations to converge. A rapidly converging iterative procedure for solving the above nonlinear unconstrained optimization problem is also presented. This procedure typically requires less than five iterations to converge. >
