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.

Method and apparatus for reproducing audio having auto volume controlling function

Abstract: A method and an apparatus for reproducing audio having an auto volume controlling function are provided to differently adjust volumes depending on each frequency band in consideration of user input volume and equal loudness curves. An apparatus for reproducing audio having an auto volume controlling function includes a band splitter(110), an audio monitoring unit(120), and a volume controller(130). The band splitter splits a reproduced audio signal according to each frequency band by using a band pass filter or a quadrature mirror filter. The audio monitoring unit calculates energy of the audio signals split on the basis of a user input volume value and audio reproducing information. The volume controller splits the audio signal according to the frequency bands by using the band pass filter and the quadrature mirror filter and differently adjusts amplitudes of the split audio signals according to the frequency bands depending on volume control values generated from the audio monitoring unit.

An Improved UWB Transmitted Reference System Based on Wavelet Decomposition

Abstract: A simple channel estimator for UWB transmitted reference system is developed by exploiting the properties of wavelet analysis. Different from conventional TR system, which conducts correlation with an analogy device and samples the signal at sub-Nyquist rate, however at the cost of performance, the proposed receiver firstly samples the received signal at a higher rate, and then passes the discrete signal through a low pass filter which is one branch of the quadrature mirror filter banks. The channel estimator ultimately reduces to this low pass filter and an additional averaging process block. The filter not only suppresses the noise contained in signals but also approximates the composite channel pulse response. Simulation results show that the approach performs better than the conventional TR and averaging only approach.

Design of FIR Quadrature Mirror-Image Filter Banks Using Fuzzy Adaptive Simulated Annealing

Abstract: An alternative approach for designing quadrature mirror filter (QMF) banks is presented. Although it is used in this paper to fit filter banks to frequency domain specifications, the method is able to be used in other tasks of digital filter synthesis, when it is possible to convert the original problem into a global minimization one. Here, the overall target is to find adequate coefficients for the prototype filter H 0 , so that the filter banks satisfy jointly global performance indices, such as the ripple in the frequency response of the whole system and out of band rejection of the prototype filter. The chosen global optimization algorithm is based upon the well-known simulated annealing paradigm and its implementation known as fuzzy adaptive simulated annealing. The method starts from frequency domain constraints to a generic, parameterized QMF bank family, synthesizes a corresponding real-valued cost function (of prototype filter coefficients) reflecting those constraints and, finally, obtains particular parameter values that determine the proposed optimal system. Besides, it will be presented a multi-objective approach to that classical problem that will make it possible to evaluate tradeoffs involving the complexity of the prototype filter and the reconstruction error produced by the resulting filter bank.

Quadrature distortion cancellation system

Abstract: High definition or enhanced television signals include supplementary information which is double-sideband modulated in quadrature with the picture carrier, and passed through an inverse Nyquist filter (222) before being combined (224) with a conventional vestigial sideband (221) modulated main video signal. A receiver which recovers both the main video signal and the supplementary information processes the received video signal through an IF filter (228) having a vestigial sideband frequency response characteristic. Two synchronous detectors (230, 232) recover in-phase and quadrature phase signal components from the filtered television signals, these recovered signals each include quadrature crosstalk distortion components from the other signal. The crosstalk from the supplementary signal into the main signal is cancelled by filtering (246) the recovered quadrature signal and adding (244) the result to the recovered in-phase signal. This filtering also equalizes the in-phase signal by converting the quadrature distortion components in the recovered quadrature signal into reinforcing signal components in the in-phase signal. This signal recovery system is advantageously used with a ghost cancellation system.

Implementation of QMF filters bank under several configurations on transputer card B008

Abstract: In this paper, we present the study and the simulation of a quadrature mirror filter (QMF) bank and the effect of the parallelism when it is implemented on a transputer card B008.