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Showing papers on "Quadrature mirror filter published in 2005"


Patent
Ole Kirkeby1, Jarmo Hiipakka1
21 Apr 2005
TL;DR: In this paper, a warped processing module modifies a spectral content of a digital audio signal with a set of gains for a plurality of non-linearly-scaled frequency bands determined by a warping factor λ of a warped delay line.
Abstract: This invention describes a method for adjusting loudness and spectral content of digital audio signals in a real-time using warped spectral filtering. A warped processing module modifies a spectral content of a digital audio signal with a set of gains for a plurality of non-linearly-scaled frequency bands determined by a warping factor λ of a warped delay line. Warped delay line signals, generated by the warped delay line, are processed by a warped filter block containing multiple warped finite impulse response filters, e.g., Mth band filters, using individual warped spectral filtering in said plurality of the non-linearly-scaled frequency bands, which is followed by a conventional processing by a dynamic range control/equalization block. The present invention describes another innovation, that is embedding the warped processing module in a two-channel quadrature mirror filter (QMF) bank for improving processing efficiency at high sample rates.

67 citations


Journal ArticleDOI
TL;DR: This paper proposes a new method to solve the low-order IIR filter bank design, which is based on tractable linear-matrix inequality (LMI) optimization, and focuses on the quadrature mirror filterBank design.
Abstract: The advantage of infinite-impulse response (IIR) filters over finite-impulse response (FIR) ones is that the former require a much lower order (much fewer multipliers and adders) to obtain the desired response specifications. However, in contrast with well-developed FIR filter bank design theory, there is no satisfactory methodology for IIR filter bank design. The well-known IIR filters are mostly derived by rather heuristic techniques, which work in only narrow design classes. The existing deterministic techniques usually lead to too high order IIR filters and thus cannot be practically used. In this paper, we propose a new method to solve the low-order IIR filter bank design, which is based on tractable linear-matrix inequality (LMI) optimization. Our focus is the quadrature mirror filter bank design, although other IIR filter related problems can be treated and solved in a similar way. The viability of our theoretical development is confirmed by extensive simulation.

29 citations


Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this paper, a new idea for generation of quadrature signals on chip is presented, based on a passive RC polyphase filter, where the resistive parts are made active by using inverters.
Abstract: A new idea for generation of quadrature signals on chip is presented. The topology is based on a passive RC polyphase filter, where the resistive parts are made active by using inverters. The active filter combines quadrature generation, isolation, and gain without losing quadrature performance compared to a regular RC polyphase filter. The filter technique is demonstrated in a 10GHz front-end application where a broadband VCO drives an active polyphase filter to generate quadrature LO signals. By avoiding a quadrature VCO and tuned buffers, significant reductions in chip area are possible.

21 citations


Patent
05 Apr 2005
TL;DR: In this paper, the authors proposed a method to compensate for quadrature impairments of an analog quadratures modulator and/or demodulator over a relatively wide signal bandwidth.
Abstract: The present invention is related to methods and apparatus that compensate for quadrature impairments of an analog quadrature modulator and/or demodulator over a relatively wide signal bandwidth. One embodiment pre-distorts baseband signals in a quadrature modulator compensation signal processor (QMCSP) to negate the quadrature impairment of an analog quadrature modulator and corrects a received baseband signal in a quadrature demodulator compensation signal processor (QDCSP) to cancel the quadrature impairment of an analog quadrature demodulator. The QMCSP and the QDCSP contain adaptive digital filter correction structures that pre-compensate and post-compensate, respectively, for the quadrature impairments introduced by the analog quadrature modulator and the analog quadrature demodulator over a relatively wide bandwidth. A phase shifter advantageously shifts the phase of a local oscillator signal to the analog quadrature demodulator to distinguish quadrature impairments introduced by the modulation path from quadrature impairments introduced by the demodulation path.

20 citations


Patent
Kim Young Jin1
05 Aug 2005
TL;DR: In this article, the performance of a direct-conversion receiver (DCR) can be improved by employing a frequency-mixing device capable of enhancing a linearity of a frequency mixer.
Abstract: A frequency-mixing method includes a step of generating a first quadrature signal having a predetermined frequency, a second quadrature signal having a phase difference of about 180 degrees with respect to a phase of the first quadrature signal, a third quadrature signal having a phase difference of about 90 degrees with respect to the phase of the first quadrature signal and a fourth quadrature signal having a phase difference of about 90 degrees with respect to a phase of the second quadrature signal; a step of controlling a phase of the third quadrature signal and a phase of the fourth quadrature signal so as to control a linearity of a frequency mixer; and a step of down-converting a radio frequency (RF) signal using the first through the fourth quadrature signals. Accordingly, performance of a direct-conversion receiver (DCR) can be improved by employing a frequency-mixing device capable of enhancing a linearity of a frequency mixer.

19 citations


Journal ArticleDOI
TL;DR: A Neumann series approximation is proposed, which is a band matrix truncation of the optimal prefilter, and simple formulas for the operator norm approximation error are derived.
Abstract: A wavelet prefilter maps sample values of an analyzed signal to the scaling function coefficient input of standard discrete wavelet transform (DWT) algorithms. The prefilter is the inverse of a certain postfilter convolution matrix consisting of integer sample values of a noninteger-shifted wavelet scaling function. For the prefilter and the DWT algorithms to have similar computational complexity, it is often necessary to use a "short enough" approximation of the prefilter. In addition to well-known quadrature formula and identity matrix prefilter approximations, we propose a Neumann series approximation, which is a band matrix truncation of the optimal prefilter, and derive simple formulas for the operator norm approximation error. This error shows a dramatic dependence on how the postfilter noninteger shift is chosen. We explain the meaning of this shift in practical applications, describe how to choose it, and plot optimally shifted prefilter approximation errors for 95 different Daubechies, Symlet, and B-spline wavelets. Whereas the truncated inverse is overall superior, the Neumann filters are by far the easiest ones to compute, and for some short support wavelets, they also give the smallest approximation error. For example, for Daubechies 1-5 wavelets, the simplest Neumann prefilter provide an approximation error reduction corresponding to 100-10 000 times oversampling in a nonprefiltered system.

18 citations


Proceedings ArticleDOI
14 Nov 2005
TL;DR: Two new algorithms to compute the direct and the inverse discrete wavelet transform of continuous streams of data are discussed in this paper, optimized to be used in uniprocessor systems, presenting as one of their main features the ability to compute over the borders of the data segments without relying on any techniques that are traditionally used for thus task.
Abstract: Two new algorithms to compute the direct and the inverse discrete wavelet transform of continuous streams of data are discussed in this paper. The algorithms are optimized to be used in uniprocessor systems, presenting as one of their main features the ability to compute over the borders of the data segments without relying on any techniques that are traditionally used for thus task, like zero padding. A modified version of the recursive pyramid algorithm was used to compute the direct transform, keeping just the features to minimize data storage but eliminating its dependency on extension techniques. The inverse transform is computed by an algorithm inspired in the RPA, the quadrature mirror filter bank and the overlap-save method for filter convolutions. To evaluate the performance the algorithms were implemented on a DSP coupled to a digitizer through its external memory bus, what allowed deterministic behavior. After a stage of optimization an analysis of data storage and computation load were made. These results and the potential applications are discussed at the end of the paper.

18 citations


Proceedings ArticleDOI
27 May 2005
TL;DR: In this paper, a GA was used to design quadrature mirror filter (QMF) banks and a unique GA was developed to optimize filter bank coefficients such that the corresponding system response matches that of an ideal system with an additional constraint that all coefficients are in canonical signed digit (CSD) format.
Abstract: In this paper, a genetic algorithm (GA) is used to design quadrature mirror filter (QMF) banks. A unique genetic algorithm (GA) is developed to optimize filter bank coefficients such that the corresponding system response matches that of an ideal system with an additional constraint that all coefficients are in canonical signed digit (CSD) format. A special restoration technique is used to restore the CSD format of the coefficients after crossover and mutation operators in the GA. The proposed restoration technique maintains the specified wordlength and the maximum number of nonzero digits in the filter bank coefficients.

15 citations


Journal ArticleDOI
TL;DR: The orthonormal wavelet bases are generated from Haar and Daubechies Quadrature Mirror Filter bank and the BER performance of this system as compared to Fourier based V-BLAST system shows significant improvement.
Abstract: Wavelet based OFDM V-BLAST system design and its simulation results are briefly discussed in this article. The orthonormal wavelet bases are generated from Haar and Daubechies Quadrature Mirror Filter (QMF) bank. The BER performance of this system as compared to Fourier based OFDM V-BLAST system shows significant improvement.

14 citations


Proceedings ArticleDOI
18 Mar 2005
TL;DR: A novel steganalysis technique for halftone images without knowledge of the original cover image is presented and a statistical classifier is designed to detect marked images.
Abstract: We present a novel steganalysis technique for halftone images without knowledge of the original cover image. We first convert halftone images into grayscale-like images by low-pass filtering. The low-pass-filtered image is then decomposed using quadrature mirror filters, and a set of subband coefficients are generated at different scales and orientations. Next, a set of statistical features are computed from the subband coefficients and their predicated errors. Using Fisher linear discriminant analysis, a statistical classifier is designed to detect marked images. Experimental results demonstrate the effectiveness and accuracy of the proposed technique.

12 citations


Patent
04 Oct 2005
TL;DR: In this paper, a method for suppression of a perturbing quadrature component of a carrier signal of an amplitude-modulated signal during the recovery of the carrier signal in a synchronous demodulator was proposed.
Abstract: The invention relates to a method as well as a circuit arrangement for suppression of a perturbing quadrature component of a carrier signal of an amplitude-modulated signal during the recovery of the carrier signal in a synchronous demodulator, which outputs a quadrature signal (Q). The perturbing quadrature component of the carrier signal is estimated and the estimated quadrature component is subtracted from the quadrature signal (Q).

Journal ArticleDOI
TL;DR: A method using the breeder genetic algorithm to design a composite wavelet matched filter for face recognition that can be used in an optical correlator to separate two classes of input face images.

Patent
23 Jun 2005
TL;DR: In this paper, a correction engine using first filter coefficients to compensate for I/Q mismatch present in a received quadrature signal is described, and an adaptation engine to adapt second filter coefficients based on the mismatch present.
Abstract: Methods and apparatus to compensate for I/Q mismatch in quadrature receivers are disclosed. An example apparatus disclosed herein comprises a correction engine using first filter coefficients to compensate for I/Q mismatch present in a received quadrature signal; an adaptation engine to adapt second filter coefficients based on I/Q mismatch present in the received quadrature signal; and coefficient controller to occasionally adjust the first filter coefficients based on the second filter coefficients.

Patent
Takashi Kato1
10 Feb 2005
TL;DR: In this article, the error determining part determines, based on the measurement result of the power detector, the error of the quadrature modulation, which is determined by the power measurement of the adder.
Abstract: An RF signal, which has been obtained by a quadrature modulation, is corrected without performing quadrature demodulation. There are included an in-phase multiplier, a quadrature multiplier, an adder, a power detector, and an error determining part. The in-phase multiplier outputs an in-phase conversion signal by mixing an in-phase local signal of a predetermined local frequency with an in-phase correction user signal obtained by adding an in-phase user signal to an in-phase correction signal of a sinusoidal voltage outputted from an in-phase correction signal output unit. The quadrature multiplier outputs a quadrature conversion signal by mixing a quadrature local signal, which is different in phase by 90 degrees from the in-phase local signal, with a quadrature correction user signal obtained by adding a quadrature user signal to a quadrature correction signal, which is different in phase by 90 degrees from the in-phase correction signal, from a quadrature correction signal output unit. The adder adds the in-phase conversion signal to the quadrature conversion signal. The power detector measures an output voltage of the adder. The error determining part determines, based on the measurement result of the power detector, the error of the quadrature modulation.

Proceedings ArticleDOI
24 Jun 2005
TL;DR: In this paper, an isotropic quadrature filter for 3D images is presented, which can calculate the local orientation, energy and the phase of locally intrinsically 1D structuresy in 3D image data.
Abstract: Quadrature filters are a well known means for local spectral analysis of images and to extract relevant structure. Recently, there has been the discovering of an isotropic quadrature filter for images that does not need steering with respect to orientation and provides the user with geometric (local orientation) and structural (local phase) information. Here, we present a further extension of this, an isotropic quadrature filter for 3D data. With only four convolutions we can calculate the local orientation, energy and the phase of locally intrinsically 1D structuresy in 3D image data. There is a wide variety of useful applications for a filter of this kind. In this paper, we will restrict ourselves to the application of phase-based motion or flow field estimation.

Journal ArticleDOI
TL;DR: An efficient subband adaptive beamforming array (ABA) using a quadrature mirror filter (QMF) bank is presented and shows improved signal gain and deep suppression of the interference in the direction perpendicular to the ABA.
Abstract: An efficient subband adaptive beamforming array (ABA) using a quadrature mirror filter (QMF) bank is presented. For wideband beamforming, taps have to be added to the full-band ABA for efficient suppression of the interference. However, the introduction of multiple taps results in the addition of uncorrelated noise to the ABA. This results in power loss in the direction perpendicular to the ABA. In order to compensate for the loss introduced by the addition of taps, the proposed concept is investigated. This configuration shows improved signal gain and deep suppression of the interference in the direction perpendicular to the ABA.

Proceedings ArticleDOI
14 Nov 2005
TL;DR: This paper introduces a family of non-adaptive geometrical wavelets that have high anisotropy and directionality and derive from a single non-separable filter bank structure that is designed from 1-D and quincunx filters.
Abstract: This paper introduces a family of non-adaptive geometrical wavelets that have high anisotropy and directionality. Unlike curvelets and contourlets, they have no redundancy and form orthonormal bases of L/sup 2/ (R/sup 2/). Their implementation derives from a single non-separable filter bank structure that is designed from 1-D and quincunx filters.

Journal ArticleDOI
TL;DR: It turns out that the 2D wavelets in this class are intimately related to some underlying 1D wavelet, and it is explained how this relation can be realized by means of a lifting scheme, thus allowing an efficient implementation.
Abstract: In the literature 2D (or bivariate) wavelets are usually constructed as a tensor product of 1D wavelets. Such wavelets are called separable. However, there are various applications, e.g. in image processing, for which non-separable 2D wavelets are prefered. In this paper, we investigate the class of compactly supported orthonormal 2D wavelets that was introduced by Belogay and Wang.2 A characteristic feature of this class of wavelets is that the support of the corresponding filter comprises only two rows. We are concerned with the biorthogonal extension of this kind of wavelets. It turns out that the 2D wavelets in this class are intimately related to some underlying 1D wavelet. We explore this relation in detail, and we explain how the 2D wavelet transforms can be realized by means of a lifting scheme, thus allowing an efficient implementation. We also describe an easy way to construct wavelets with more rows and shorter columns.

Journal ArticleDOI
TL;DR: In this article, a new approach for optimization based stable linear-phase infinite impulse response (IIR) perfect reconstruction quadrature mirror filter (PRQMF) bank design was proposed.
Abstract: In this paper, we propose a new approach for optimization based stable linear-phase infinite impulse response (IIR) perfect reconstruction quadrature mirror filter (PRQMF) bank design. To this end, the design problem is formulated using stop-band energy, stability, transition-band, pass-band and stop-band ripples requirements as constraints. Lagrange multiplier method is used for the solution of optimization-based design problem. The brief conclusion with design example that illustrates the proposed design method is presented.

Proceedings ArticleDOI
23 May 2005
TL;DR: The design of the corresponding pair of filter banks that defines (generate) these wavelets have exact linear phase which yields biorthogonal wavelets with exact symmetry.
Abstract: A Hilbert pair is defined as a pair of wavelet functions that are approximate Hilbert transform of each other. This paper presents the design of the corresponding pair of filter banks that defines (generate) these wavelets. The filters have exact linear phase which yields biorthogonal wavelets with exact symmetry. The technique is based on matching a given even-length filter bank with an odd-length filter bank. The class of THFB (triplet halfband filter bank) is utilized in the matching design. The parameteric Bernstein is used for the construction of the three kernels that define the THFB and the perfect reconstruction and vanishing moments properties are structurally imposed. A least-least squares formulation of the design problem is used and this yields good results.

Patent
23 Jun 2005
TL;DR: In this article, a correction engine using first filter coefficients to compensate for I/Q mismatch present in a received quadrature signal is described, and an adaptation engine to adapt second filter coefficients based on the mismatch present.
Abstract: Methods and apparatus to compensate for I/Q mismatch in quadrature receivers are disclosed. An example apparatus disclosed herein comprises a correction engine using first filter coefficients to compensate for I/Q mismatch present in a received quadrature signal; an adaptation engine to adapt second filter coefficients based on I/Q mismatch present in the received quadrature signal; and coefficient controller to occasionally adjust the first filter coefficients based on the second filter coefficients.


Journal ArticleDOI
TL;DR: The optimal design of complex infinite impulse response (IIR) two-channel quadrature mirror filter (QMF) banks with equiripple frequency response is considered and a variant of Karmarkar's algorithm is used to efficiently solve the optimization problem through a frequency sampling and iterative approximation method.
Abstract: The optimal design of complex infinite impulse response (IIR) two-channel quadrature mirror filter (QMF) banks with equiripple frequency response is considered. The design problem is appropriately formulated to result in a simple optimization problem. Therefore, based on a variant of Karmarkar's algorithm, we can efficiently solve the optimization problem through a frequency sampling and iterative approximation method to find the complex coefficients for the IIR QMFs. The effectiveness of the proposed technique is to form an appropriate Chebyshev approximation of a desired response and then find its solution from a linear subspace in several iterations. Finally, simulation results are presented for illustration and comparison.

Proceedings ArticleDOI
23 May 2005
TL;DR: Through the proposed structure, it is now possible to segment the 2D frequency components of a 2D digital signal/image arbitrarily through a careful design of the scaling matrix while still preserving the PR property.
Abstract: In this paper, we propose a new method to realize an irrational scaling of a 2D digital signal/image. This method is suitable for any scaling matrices with real entries, including irrational numbers. Based on this algorithm, a new structure of a 2D four-channel non-uniform perfect reconstruction filter bank is derived. Through the proposed structure, it is now possible to segment the 2D frequency components of a 2D digital signal/image arbitrarily through a careful design of the scaling matrix while still preserving the PR property. Therefore, we can find many applications such as image compression and communication using this structure. The experimental results are presented at the end of this paper.

01 Jan 2005
TL;DR: In this article, the authors propose a method to solve the problem of homonymity in the context of homonyms, i.e., homophily-based homonyms.
Abstract: ................................................................................ ...............3

Journal Article
TL;DR: An improved leapfrog-type filter employing current mirror integrator and differentiator and its comparison with conventional leapfrog -type filter was given and results show that the proposed circuit is valid and feasible.
Abstract: An improved leapfrog-type filter employing current mirror integrator and differentiator and its comparison with conventional leapfrog-type filter was given. The filter implementation limitation of uniquely using current mirror integrator was broke by this improved design method. And the signal flow graph and circuit configuration for elliptic filters was simplified. PSPICE simulation at the MOS transistor level was carried out and results show that the proposed circuit is valid and feasible.

Journal Article
TL;DR: In this paper, the basic principle of quadrature coherent detector using LPF method is discussed, the flow of signal is analyzed in detail, and the definition of mirror frequency is presented explicitly in this method.
Abstract: The basic principle of quadrature coherent detector using LPF method is discussed The flow of signal is analyzed in detail The definition of mirror frequency is presented explicitly in this method Mirror frequency rejection is discussed emphatically,and simulations are made The analysis conclusion and the simulation results are instructive for eliminating mirror frequency signals in quadrature coherent detector with LPF method

Proceedings ArticleDOI
Jie-Cherng Liu1
01 Jan 2005
TL;DR: A family of the generalized quadrature modulation (GQM) structures is proposed that includes a prototype FIR or IIR filter within the structure that has the potential to exploit other applications.
Abstract: A family of the generalized quadrature modulation (GQM) structures is proposed that includes a prototype FIR or IIR filter within the structure. By choosing a proper filter and setting a single parameter many applications can be exploited, such as tunable band-pass filtering, band-pass Hubert transformation, single-sideband processing, band-inversion processing, etc. In other words, the GQM structures generalize the existing quadrature modulation systems and also have the potential to exploit other applications.

Journal Article
TL;DR: In this article, the authors give a new method to construct compactly supported symmetric and anti-symmetric orthogonal wavelets filter with scale = M. The method is simple for computation, and it only needs to solve some equations.
Abstract: We give a new method to construct compactly supported symmetric and anti-symmetric orthogonal wavelets filter with scale=M. The method is simple for computation, and it only needs to solve some equations. Finally, we give the values of real coe?cient filter and complex coe?cient filter.

Journal Article
TL;DR: Simulation shows that this digital quadrature demodulation method can accurately recover the modulating signal in low SNR circumstance.
Abstract: A digital quadrature demodulation method for Frequency Modulated (FM) signals is proposed. The received FM signal is first downconverted to baseband using digital quadrature carriers generated by DDS. Then a decimation FIR filter and a digital differentiator are used to obtain the modulating signal. Simulation shows that this method can accurately recover the modulating signal in low SNR circumstance.