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.
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TL;DR: The design problem is presented systematically as an unconstrained optimization that minimizes the weighted sum of error of transfer function of the filter bank at quadrature frequency, stopband energy and the passband error of a prototype filter (PF).
Abstract: This paper proposes an algorithm to design a two-channel linear phase quadrature mirror filter (QMF) bank. The design problem is presented systematically as an unconstrained optimization that minimizes the weighted sum of error of transfer function of the filter bank at quadrature frequency, stopband energy and the passband error of a prototype filter (PF). A new method is developed for the design of a low pass prototype filter for QMF banks. For solving given optimization problem, Quasi-Newton optimization technique is used. Numerical examples and comparisons with several existing methods are included to show the performances and effectiveness of this method. An application of the proposed method is considered in the area of subband coding of the images.
37 citations
14 Apr 1991
TL;DR: The authors present a derivation of the necessary and sufficient condition on the polyphase components of a linear-phase prototype such that the poly phase component matrix of the filter bank is lossless and ensures that the modulated filter bank satisfies the PR (perfect reconstruction) property.
Abstract: The authors present a derivation of the necessary and sufficient condition on the polyphase components of a linear-phase prototype (length N=2 mM) such that the polyphase component matrix of the filter bank is lossless. This in turn ensures that the modulated filter bank satisfies the PR (perfect reconstruction) property. An efficient design procedure (which involves fewer parameters to be optimized than other approaches) is presented. By this approach, FIR (finite-impulse-response) PR filter banks can be designed for an arbitrary number of channels. Moreover, since both the analysis and synthesis filter banks are obtained by modulation, they can be implemented very efficiently (using the discrete cosine transform). The design procedure is outlined and a design example is presented. >
37 citations
TL;DR: An analytical formula is given, which allows one to optimize the design of the basic low-pass FIR filter by means of a straight nonlinear minimization procedure.
Abstract: Quadrature mirror filters have an outstanding relevance in the implementation of filter banks for dividing the speech signal into frequency bands and for reconstructing it from these subbands. An analytical formula is given, which allows one to optimize the design of the basic low-pass FIR filter by means of a straight nonlinear minimization procedure.
37 citations
TL;DR: Several theorems are proved and the bridge between the continuous and discrete adaptive wavelet transform (AWT) is constructed explicitly, which is the implementation by means of wavelet chips and neurochips, in which each node is a daughter wavelet similar to a radial basis function using dyadic affine scaling.
Abstract: We prove several theorems and construct explicitly the bridge between the continuous and discrete adaptive wavelet transform (AWT). The computational efficiency of the AWT is a result of its compact support closely matching linearly the signal's time-frequency characteristics, and is also a result of a larger redundancy factor of the superposition-mother s(x) (super-mother), created adaptively by a linear superposition of other admissible mother wavelets. The super-mother always forms a complete basis, but is usually associated with a higher redundancy number than its constituent complete orthonormal (CON) bases. The robustness of super-mother suffers less noise contamination (since noise is everywhere, and a redundant sampling by bandpassings can suppress the noise and enhance the signal). Since the continuous super-mother has been created off-line by AWT (using least-mean-squares neural nets), we wish to accomplish fast AWT on line. Thus, we formulate AWT in discrete high-pass (H) and low-pass (L) filter bank coefficients via the quadrature mirror filter (QMF), a digital subband lossless coding. A linear combination of two special cases of the complete biorthogonal normalized (Cbi-ON) QMF [L(z),H(z),L+(z),H+(z)], called α-bank and β-bank, becomes a hybrid aα + bβ-bank (for any real positive constants a and b) that is still admissible, meaning Cbi-ON and lossless. Finally, the power of AWT is the implementation by means of wavelet chips and neurochips, in which each node is a daughter wavelet similar to a radial basis function using dyadic affine scaling.
37 citations
Patent•
13 Dec 1999TL;DR: In this article, an electronic counter-measure receiver can be colocated with a threat simulator radar, which transmits a radar signal, which is sampled as a reference signal by the receiver to determine quadrature, coherent matched filter coefficients.
Abstract: An electronic counter-measure receiver can be colocated with a threat simulator radar, which transmits a radar signal. As a pulsed-Doppler signal, this transmitted radar signal is sampled as a reference signal by the receiver to determine quadrature, coherent matched filter coefficients. A return signal is received and processed with the reference signal as quadrature signal components with the quadrature, coherent matched filter coefficients within a matched filter. The return signal is processed as a first intermediate frequency via a mixer and local oscillator and a second quadrature intermediate frequency via a digital local oscillator and mixer. A fast Fourier transform is performed to determine Doppler information. In a continuous wave transmission for sampling arbitrary but unevenly spaced in time pulses are generated from a pulse generator source internal to the receiver.
37 citations