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Fast implementation of oversampled modulated filter banks

ELECTRONICS LETTERS 2000年第17期36卷 1502-1503页

作者： Weiss, S Stewart, RW Univ Southampton Dept Elect & Comp Sci Commun Res Grp Southampton SO17 1BJ Hants England Univ Strathclyde Dept Elect & Elect Engn Glasgow G1 1XQ Lanark Scotland

The authors present an efficient implementation of oversampled filter banks derived from a prototype filter by modulation. Via a polyphase analysis, redundancies in the filter operations are removed. With some modific... 详细信息

关键词： channel bank filters redundancies filtering theory filtering methods in signal processing polyphase analysis oversampled modulated filter banks Computational complexity filter operations signal processing theory computational complexity

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2D FIR Wiener filter realisation using orthogonal lattice structures

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ELECTRONICS LETTERS 2000年第12期36卷 1078-1079页

作者： Kayran, AH Eksioglu, E Istanbul Tech Univ Dept Elect Engn TR-80626 Istanbul Turkey

A new realisation algorithm for 2D FIR Wiener filters is proposed. The reduced-order 2D orthogonal lattice filter structure is used as the principal component as in the 1D case. A numerical example is included to veri... 详细信息

关键词： filtering theory transfer functions filtering methods in signal processing 2D FIR Wiener filter realisation orthogonal backward prediction error fields FIR filters two-dimensional digital filters correlation methods orthogonal lattice structures reduced-order 2D orthogonal lattice filter structure Toeplitz matrices Algebra Digital filters numerical example block-Toeplitz matrix Wiener filters correlation values lattice filters

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signal-dependent film grain noise generation using homomorphic adaptive filtering

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 2000年第3期147卷 283-287页

作者： Campisi, P Yan, JCK Hatzinakos, D Univ Roma TRE Dipartimento Ingn Elettron I-00146 Rome Italy ATI technol Inc Unionville ON Canada Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

A technique for the generation of signal-dependent film grain noise is presented. It finds applications in television and motion picture productions where artificial film grain noise is added to computer-generated synthetic images to give them a realistic appearance. After decoupling the signal from the noise, using the generalised homomorphic transformation, the noise is removed from the noisy image using the proposed adaptive filtering scheme. The noise parameter is then estimated using the higher-order statistics (skewness or kurtosis) of the observed image and the filtered image statistics, and it is used to generate film grain noise. Computer simulation results demonstrate the effectiveness of the proposed method.

关键词： adaptive filters adaptive signal processing noise generators homomorphic adaptive filtering filtered image statistics noisy image computer simulation results skewness television production kurtosis Computer vision and image processing techniques filtering methods in signal processing artificial film grain noise signal-dependent film grain noise generation noise parameter estimation computer-generated synthetic images Optical, image and video signal processing image processing higher order statistics cinematography Other topics in statistics observed image filtering theory generalised homomorphic transformation motion picture production higher-order statistics

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New technique for designing nearly orthogonal wavelet filter banks with linear phase

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 2000年第6期147卷 527-533页

作者： Zhao, Y Swamy, MNS Concordia Univ Dept Elect & Comp Engn Ctr Signal Proc & Commun Montreal PQ H3G 1M8 Canada

A new technique based on nonlinear optimisation to design nearly orthogonal wavelet filter banks with linear phase is proposed. The main idea is to impose a certain number of zeros at z = -1 for a symmetric filter and make it satisfy the power complementary condition as accurately as possible. From this filter, a semi-orthogonal wavelet filter bank which is nearly orthogonal can be constructed. This semi-orthogonal filter bank can be approximately implemented using a filter bank consisting of only one prototype filter. The frequency selectivity can also be designed at the same time by using a weighted cost function.

关键词： Digital signal processing poles and zeros Optimisation techniques channel bank filters digital filters network synthesis weighted cost function prototype filter zeros Digital circuit design, modelling and testing filtering methods in signal processing nonlinear optimisation Integral transforms in numerical analysis symmetric filter nearly orthogonal wavelet filter banks design linear phase filters circuit optimisation power complementary condition semi-orthogonal wavelet filter bank wavelet transforms Digital filters frequency selectivity

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Synthesis of a periodically time-varying digital filter

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 2000年第5期147卷 393-399页

作者： Cherniakov, M Sizov, VI Donskoi, L Univ Birmingham Sch Elect & Elect Engn Birmingham B15 2TT W Midlands England Moscow Inst Elect Engn Moscow 103498 Russia Univ Queensland Dept Comp Sci & Elect Engn Brisbane Qld 4072 Australia

The paper presents an approximate method of periodically linear time-varying (PLTV) digital filter (DF) synthesis through mean values of their coefficients in time. The recursive and nonrecursive PLTV DFs of the first, second and arbitrary orders are considered. It is shown that PLTV DFs have distinguishing features which give them advantages in some applications in comparison with linear time-invariant (LTI) DFs.

关键词： frequency characteristics generalised transfer function digital signal processing approximation theory digital filter synthesis periodically time-varying digital filter network synthesis recursive filters narrowband filters Digital circuit design, modelling and testing filtering methods in signal processing transfer functions Time varying and switched networks generalised frequency function Green's function Interpolation and function approximation (numerical analysis) time-varying filters nonrecursive digital filter recursive digital filter filter coefficients approximate method Digital filters

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Directional diversity of HF signals received over high latitude paths, and the possibility of improved data throughput by means of spatial filtering

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IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION 2000年第6期147卷 487-494页

作者： Warrington, EM Jackson, CA Lundborg, B Univ Leicester Dept Engn Leicester LE1 7RH Leics England Def Res Estab S-58111 Linkoping Sweden

The high latitude ionosphere is a dynamic propagation medium in which HF radio signals associated with each propagation mode may arrive at the receiver over a range of angles in both azimuth and in elevation. Furthermore, ionospheric movements at the reflection points impose Doppler shifts and Doppler spreads onto the signals. Large Doppler spreads and multipath propagation in which the delay spread is large are particularly prevalent at these northerly latitudes and can result in a significant degradation in the performance of digital communication systems. This investigation suggests that the application of spatial filtering from simple antenna arrays comprising pairs or triplets of antennas can significantly reduce the level of apparent Doppler spreading, frequently to levels at which modern, high speed modems are expected to operate satisfactorily. The investigation concentrated on Doppler spread since this was the most significant factor in the data employed in this study: however, it is noted that reductions in effective multipath delay spread are also possible.

关键词： array signal processing Antenna arrays spatial filtering delays Doppler shift diversity reception data communication ionospheric electromagnetic wave propagation modems filtering methods in signal processing Modems HF radio propagation data throughput Doppler shifts multipath propagation high latitude ionosphere Radiowave propagation high latitude paths digital communication systems antenna arrays Doppler spreads ionospheric disturbances high speed modems reflection points HF radio signals multipath delay spread reduction filtering theory ionospheric movements multipath channels spatial filters directional diversity Radio links and equipment delay spread

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Generalisation of constant coefficient tracking filters to smooth velocity measurements

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IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 2000年第6期147卷 270-275页

作者： Portas, JAB Rodríguez, FJJ Herrero, JG Corredera, JRC Univ Politecn Madrid ETSI Telecomun Dept Senales Sistemas & Radiocomun Madrid Spain

The equations describing the new constant coefficient alpha2-beta2 tracking filter, which is capable of smoothing position and velocity measurements, are presented and its stability conditions and transient and steady state estimation errors are analytically characterised. The filter's performance is demonstrated comparing it with some other simple trackers for the same application. The example used is an air traffic control (ATC) application, consisting in the smoothing of Differential GPS (DGPS) measurements transmitted by aircraft through an automatic dependent surveillance - broadcast (ADS-B) channel.

关键词： DSPS measurements automatic dependent surveillance-broadcast channel Error analysis in numerical methods steady state estimation error Global Positioning System tracking filters differential GPS Velocity, acceleration and rotation measurement filter stability filter performance constant coefficient tracking filters error analysis filtering methods in signal processing position measurements circuit stability surveillance ATC application aircraft Radionavigation and direction finding velocity measurements velocity measurement velocity measurements smoothing transient state estimation error stability conditions state estimation air traffic control Air traffic control smoothing methods broadcast channels Satellite communication systems

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Design of linear-phase IIR digital filters using singular perturbational model reduction

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 2000年第5期147卷 409-414页

作者： Aldhaheri, RW King Abdulaziz Univ Dept Elect & Comp Engn Jeddah 21413 Saudi Arabia

A new technique for the design of a passband linear-phase infinite impulse response (IIR) digital filter is presented. This technique is based on computing orthonormal bases, which span the left and right invariant subspaces associated with the large and small eigenvalues of the cross-Gramian matrix W-co, which tends to be symmetric and easily constructed. The orthonormal bases are computed by using the ordered real Schur form decomposition, which has been proved to be robust and numerically stable. The proposed technique is illustrated by several examples.

关键词： IIR filters orthonormal bases invariant subspaces pass band digital filter design approximation theory cross-Gramian matrix band-pass filters network synthesis digital filters SISO FIR digital filter Linear algebra (numerical analysis) numerical stability approximation algorithm Digital circuit design, modelling and testing filtering methods in signal processing eigenvalues matrix algebra linear-phase IIR digital filters Interpolation and function approximation (numerical analysis) eigenvalues and eigenfunctions perturbation techniques linear phase filters symmetric matrix singular perturbational model reduction ordered real Schur form decomposition Digital filters

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Gain fusion algorithm for decentralised parallel Kalman filters

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IEE PROCEEDINGS-CONTROL THEORY AND APPLICATIONS 2000年第1期147卷 97-103页

作者： Paik, BS Oh, JH Korea Adv Inst Sci & Technol Dept Mech Engn Yusong Gu Taejon 305701 South Korea

A new gain fusion algorithm is proposed for application to decentralised sensor systems. The proposed algorithm gives computer-efficient suboptimal estimation results, such that it reconstructs the global estimate and covariance from local Kalman filter gains and estimates without significant loss of accuracy. Compared to the conventional algorithm, the smaller communication requirement and the removal of the calculation requirement of inverse covariances make the proposed algorithm more suitable for real time applications. A numerical example shows that the proposed algorithm provides a convincing suboptimal decentralised algorithm. In addition, the proposed gain fusion algorithm can be easily extended to accommodate local Kalman filters with reduced order.

关键词： Kalman filters filtering theory reduced order filter suboptimal decentralised algorithm multisensor systems Kalman filter decentralised sensor systems parallel algorithms gain fusion algorithm Sensor fusion filtering methods in signal processing Parallel programming and algorithm theory signal processing theory inverse covariances sensor fusion

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Improved blind image restoration scheme using recurrent filtering

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 2000年第1期147卷 23-28页

作者： Chow, TWS Li, XD Cho, SY City Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Peoples R China

In the paper: the idea of space-adaptive regularisation is introduced into the nonnegativity and support constraints recursive inverse filtering (NAS-RIF) algorithm for blind image restoration. A newly developed cost function is obtained by adding a space-adaptive regularisation term to the cost function of the NAS-RIF algorithm to prevent noise amplification and to reduce ringing artifacts. Compared to the original NAS-RIF algorithm, the improved NAS-RIF algorithm is particularly effective under low SNR conditions, Also, the experimental results show that the co-vergence characteristic of the improved NAS-RIF algorithm is much more stable and the converged solution is capable of providing an excellent estimate of the original image.

关键词： signal processing theory recursive filters space-adaptive regularisation convergence of numerical methods adaptive filters blind image restoration scheme convergence characteristic NAS-RIF algorithm image restoration low SNR conditions recurrent filtering Optical, image and video signal processing nonnegativity cost function filtering methods in signal processing Computer vision and image processing techniques ringing artifacts support constraints recursive inverse filtering

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