Topic
Quadrature mirror filter
About: Quadrature mirror filter is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 28900 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, a design method for two-band analysis and synthesis of IIR QMF is treated, where the phase characteristics are allowed to be nonlinear and the conditions to be satisfied by factors of the transfer function by a successive approximation is known.
Abstract: In the subband coding system which is a low bit rate speed transmission one, a multirate quadrature mirror filter (QMF) bank is used by which voice signals are divided into two or more frequency bands and recombined. In this paper, a design method for two-band analysis and synthesis IIR QMF is treated. For the phase characteristics being allowed to be nonlinear, the conditions to be satisfied by factors of the IIR QMF transfer function are known and, based on it, a design method of the transfer function by a successive approximation is known. the method in this paper does not use successive approximation. an analog filter with simultaneous Chebyshev characteristics in both the pass-and stopbands is designed so that its squared magnitude response has an odd symmtry around its half-magnitude point on the logarithmic frequency scale. Then it is bilinear transformed into a digital filter so that the analog half-magnitude frequency is mapped onto the point with the digital frequency of w = π/2T. By combining this filter and the high-pass filter obtained by shifting the former by w π/T, an exact QMF response can be obtained with analytical rigor. A design example is also presented.
01 Jan 2007
TL;DR: In this paper, a new family of multidimensional dimensional (MD) perfect reconstruction (PR) two channel filter banks with finite impulse response (FIR) filters induced from systems of biorthogonal MD scaling functions and wavelets is introduced.
Abstract: A new family of multidimensional dimensional (MD) perfect reconstruction (PR) two channel filter banks with finite impulse response (FIR) filters induced from systems of biorthogonal MD scaling functions and wavelets are introduced. One of the advantages of this construction is that the biorthogonal scaling functions and wavelets are easy to establish due to the interpolatory property of the scaling functions to start with. The other advantage is that all filters can be centrosymmetric or bi-linear phase. Examples of two dimensional (2D) bi-linear phase PR twochannel FIR filter banks will be demonstrated.
TL;DR: In this paper, a time domain analysis of two-channel quadrature mirror filter (QMF) bank has been presented, where symmetry properties of the filters have been exploited to reduce the computational complexity.
Abstract: This manuscript presents a time domain analysis of two-channel quadrature mirror filter (QMF) bank. Product terms in the system function of the QMF bank have been replaced by the respective convolution sums. The perfect reconstruction condition and an expression for ripple energy of the QMF bank have been obtained in time domain. Symmetry properties of the filters have been exploited which obviously reduces the computational complexity.
01 Jan 1994
TL;DR: In this article, the expressions for phase and log-amplitude variances were derived for the Zernike mode on an unobscured circular aperture, and expressions to find piston and tilt on an annular aperture were derived.
Abstract: In the last chapter expressions for phase and log-amplitude variances were derived. These expressions contained an aperture filter function. In this chapter explicit filter functions are derived for many cases of interest. First, those needed to calculate variances of any Zernike mode on an unobscured circular aperture are found. Next, expressions to find piston and tilt on an annular aperture are derived.
21 Apr 1994
TL;DR: A fast, direct derivation of coarse resolution space-time images within the MRA is developed and two spatio-temporal filtering methods are described, where the orientation of surfaces in R/sup 3/ gives robust indication of image motion.
Abstract: A multiresolution analysis (MRA) of L/sup 2/(R/sup 3/), which supports an orthogonal wavelet decomposition and a quadrature mirror filter pyramid algorithm, is the framework for estimating image motion. Instead of the usual iterative pyramid algorithm, a fast, direct derivation of coarse resolution space-time images within the MRA is developed. Two spatio-temporal filtering methods are described. The orientation of surfaces in R/sup 3/ gives robust indication of image motion. However, the alternative method with oriented texture energies in the spatio-temporal image fares poorly when velocities vary. >