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Improved digital filter structure for fast moments computation

IEE PROCEEDINGS-VISION IMAGE AND signal processing 1999年第2期146卷 73-79页

作者： Wong, WH Siu, WC Hong Kong Polytech Univ Dept Elect & Informat Engn Kowloon Hong Kong

An efficient approach is introduced to implement a digital filter structure for fast moments calculation. The approach not only improves the computation efficiency, but also simplifies possible realisations using both hardware and software. A suitable filter structure for the computation of moments is reviewed. The improved filter structure is compared with conventional algorithms, and yields superior performance over other algorithms in both computational speed and complexity. The most time-consuming multiplication operations in traditional approaches can be completely eliminated, and over 60% of additions in the straightforward method can be avoided. Experimental results show that the approach requires only 20% and 88% of the computation times of the straightforward and Hatamian's digital filter approaches, respectively.

关键词： computational complexity Digital signal processing software digital arithmetic fast moments computation digital filters computation efficiency computational speed 2D moments filtering methods in signal processing multiplication operations conventional algorithms digital filter structure experimental results performance additions Digital arithmetic methods hardware Digital filters

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Target tracking using television-based bistatic radar

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IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 1999年第3期146卷 166-174页

作者： Howland, PE DERA Malvern Malvern Worcs England

The use of a non-co-operative television transmitter as the illuminator for a bistatic radar system is investigated. A signal processing scheme is developed that allows airborne targets to be detected and tracked using only the vision or sound carrier of the television broadcast. This scheme requires no synchronisation with the television transmitter, and uses the Doppler shift and bearing of target echoes to estimate the target's track. The signal processing scheme consists of a two-channel fast Fourier transform, to determine the Doppler and phase characteristics of the received signal, followed by time and frequency acting constant false alarm rate detection schemes to detect the target echoes. These echoes are corrected for phase errors arising from antenna element mutual coupling, and the corresponding bearings are calculated. A Kalman filter based tracking scheme is used to associate the individual Doppler and bearing returns belonging to different targets, resulting in Doppler and bearing profiles for each target. These are used to estimate the Cartesian co-ordinates and velocity of each target using an extended Kalman filter, initialised using a genetic algorithm and Levenberg-Marquardt optimiser. It is shown that targets can be detected and tracked over a large area, at ranges of up to 260 km.

关键词： radar signal processing Levenberg-Marquardt optimiser radar detection Radar theory sound carrier Doppler shift velocity Optimisation techniques constant false alarm rate detection schemes genetic algorithms radar tracking genetic algorithm fast Fourier transforms television-based bistatic radar filtering methods in signal processing Radar equipment, systems and applications Kalman filters two-channel fast Fourier transform vision carrier noncooperative television transmitter Doppler characteristics phase errors Cartesian co-ordinate aircraft television transmitters signal processing scheme Kalman filter based tracking scheme airborne targets target tracking Doppler radar extended Kalman filter antenna element mutual coupling target echoes phase characteristics

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Algorithmically engineered fast multichannel adaptive filter based on QR-RLS

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 1999年第1期146卷 7-13页

作者： Harteneck, M McWhirter, JG Proudler, IK Stewart, RW Univ Strathclyde Dept Elect & Elect Engn Signal Proc Div Glasgow G1 1XW Lanark Scotland DERA Malvern Malvern WR14 3PS Worcs England

A fast version of the multichannel QR algorithm for RLS adaptive filtering, with channel filters of unequal length, is derived. This is achieved by applying the techniques of algorithmic engineering to a signal flow graph representation of the basic QR RLS algorithm. By virtue of this graphical approach, the derivation is relatively straightforward and circumvents the complex and notationally verbose matrix algebra usually involved in the derivation of fast RLS algorithms in general and the previously published, unequal-length, multichannel RLS lattice algorithm in particular.

关键词： adaptive filters adaptive signal processing multichannel QR algorithm QR-RLS fast RLS algorithms recursive filters filtering methods in signal processing Interpolation and function approximation (numerical analysis) unequal length channel filters signal flow graphs algorithmic engineering fast multichannel adaptive filter RLS adaptive filtering filtering theory signal flow graph representation graphical approach least squares approximations multichannel RLS lattice algorithm lattice filters signal processing theory

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Affine-structure-based facial image encoding

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 1999年第4期146卷 211-221页

作者： Chatterjee, S Banerjee, S Biswas, KK Indian Inst Technol Dept Comp Sci & Engn New Delhi 110016 India

A real-time algorithm for affine-structure-based video compression for facial images is presented. The face undergoing motion is segmented and triangulated to yield a set of control points. The set of control points generated by triangulation are tracked across a few frames using an intensity-based correlation technique. For accurate motion and structure estimation a Kalman-filter-based algorithm is used to track features on the facial image. The structure information of the control points is transmitted only during the bootstrapping stage. After that only the motion information is transmitted to the decoder. This reduces the number of motion parameters associated with control points in each frame. The local motion of the eyes and lips is captured using local 2-D affine transformations. For real time implementation a quad-tree based search technique is adopted to solve local correlation. Any remaining reconstruction error is accounted for using predictive encoding. Results on real image sequences demonstrate the applicability of the method.

关键词： video coding Combinatorial mathematics motion parameters data compression correlation methods image motion analysis image segmentation video compression face segmentation bootstrapping facial images filtering methods in signal processing affine-structure-based facial image encoding Video signal processing Kalman filters quadtrees motion information reconstruction error real-time algorithm intensity-based correlation technique face triangulation tracking Image and video coding filtering theory feature tracking quad-tree based search technique image reconstruction local correlation Kalman-filter-based algorithm image sequences low-bit rate video real image sequences local 2D affine transformations predictive encoding

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Effects of user distribution on CDMA antenna array receivers

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IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 1999年第1期146卷 25-30页

作者： Thompson, JS Grant, PM Mulgrew, B Univ Edinburgh Dept Elect Engn Signals & Syst Grp Edinburgh EH9 3JL Midlothian Scotland

The use of sectorised antenna array receivers for the uplink of cellular code division multiple access systems is discussed. The distribution of users in the sector can seriously alter the sector capacity that can be achieved. The authors consider two algorithms, matched filtering and interference suppression, and their performance for different user distributions. Simulation results are presented to show the effect of user clustering on system performance for a number of different scenarios.

关键词： sectorised antenna array receivers cellular code division multiple access systems user distribution user clustering system performance Antenna arrays Multiple access communication receiving antennas radiofrequency interference CDMA antenna array receivers Mobile radio systems Electromagnetic compatibility and interference uplink filtering methods in signal processing radio receivers antenna arrays code division multiple access matched filtering sector capacity matched filters interference suppression cellular radio

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Obtaining medial responses from steerable filters

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 1999年第5期146卷 286-292页

作者： Bharath, AA Huberson, CJ Univ London Imperial Coll Sci Technol & Med Dept Biol & Med Syst Sir Leon Bagrit Ctr London SW7 2BX England

In building up a multiscale, medial axis representation, the generation of medial responses from a set of boundary responses at multiple scales can be a computationally intensive process. Polar separable medial weighting kernels are applied to the computation of medial responses. An approximate method for the synthesis of rotated kernels is proposed. Because of the need to not only rotate, but to displace boundary responses by an amount dependent on the image scale, the traditional steerable filter approach must be modified to yield correct medial responses. Comparisons between integral evaluation and the adaptive filtering approximations show that 100-fold increases in modestly sized images at a single scale are possible. The error in the approximation is insignificant.

关键词： integral evaluation edge strength map grey-scale images approximation theory multiscale medial axis representation image representation Computer vision and image processing techniques filtering methods in signal processing image scale rotated kernels synthesis edge detection Interpolation and function approximation (numerical analysis) boundary responses Optical, image and video signal processing polar separable medial weighting kernels medial responses adaptive filtering approximations filtering theory approximation error approximate method steerable filter steerable filters

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Fast recursive algorithms for short-time discrete cosine transform

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ELECTRONICS LETTERS 1999年第15期35卷 1236-1238页

作者： Kober, V Cristobal, G CSIC Imaging & Vis Dept Inst Opt Madrid Spain

Local adaptive signal processing can be carried out using the short-time discrete cosine transform (DCT) Two fast recursive algorithms for computing the short-time DCT are presented. The algorithms are based on a recursive relationship between three subsequent local DCT spectra. The computational complexity of the algorithms is compared with that of fast DCT algorithms.

关键词： local DCT spectra filtering theory Integral transforms in numerical analysis discrete cosine transform filtering methods in signal processing fast recursive algorithms short-time DCT Computational complexity local adaptive signal processing Digital signal processing signal processing theory discrete cosine transforms adaptive signal processing computational complexity

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Optimal spreading sequence design based on PR-QMF theory

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ELECTRONICS LETTERS 1999年第6期35卷 447-448页

作者： Shi, QH Cheng, SX Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China

Based on filter bank theory, a new scheme for spreading sequence generation is proposed for direct sequence code division multiple access (DS-CDMA) systems. It is shown that optimal spreading sequences produce much le... 详细信息

关键词： filter bank theory filtering theory interference (signal) Electromagnetic compatibility and interference filtering methods in signal processing spread spectrum communication direct sequence code division multiple access PR-QMF theory quadrature mirror filters mobile communications optimal spreading sequence design code division multiple access Multiple access communication multiple access interference

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Design and implementation of a new efficient median filtering algorithm

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 1999年第5期146卷 273-278页

作者： Hiasat, AA Al-Ibrahim, MM Gharaibeh, KM Princess Sumaya Univ Dept Elect Engn Amman 11941 Jordan Jordan Univ Sci & Technol Dept Elect Engn Irbid 3030 Jordan

A new bit-level algorithm for median-type filters, based on the concept of majority, and a new hardware implementation suitable for VLSI implementation are introduced. The proposed structure has an area complexity of O(N(N + w)) and a time complexity of O(w). Compared with other existing algorithms, the new algorithm exhibits reduced hardware requirements and better processing speed. In addition, a new application of median filtering in electrocardiograms (ECG) is presented. The new method uses the concept of median filtering to restore the baseline of an ECG signal, which is, in most cases, unstable due to artifacts, e.g. a patient's movement or breathing.

关键词： Bioelectric signals electrocardiography area complexity computational complexity hardware implementation median-type filters artifacts Digital signal processing VLSI Biology and medical computing network synthesis time complexity Digital circuit design, modelling and testing majority concept Semiconductor integrated circuits filtering methods in signal processing medical signal processing breathing electrocardiograms ECG signal filtering theory bit-level algorithm VLSI implementation patient movement efficient median filtering algorithm median filters processing speed propagation time reduction Digital filters

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Adaptive time delay and Doppler shift estimation for narrowband signals

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IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 1999年第5期146卷 243-250页

作者： Dooley, SR Nandi, AK Univ Strathclyde Dept Elect & Elect Engn Signal Proc Div Glasgow G1 1XW Lanark Scotland

A computationally inexpensive algorithm suitable for fast, high-resolution estimation of time delays and Doppler shifts (which are necessary for target ranging and tracking) between narrowband signals is presented. The algorithm uses a modulated Lagrange interpolation filter and an LMS-type algorithm. The problem of delay and Doppler estimation is reduced to a linear regression problem. Convergence and performance analysis of the method is studied both analytically and through simulation. It is demonstrated that the method provides more (or as) efficient estimates than modulated sine interpolation or the corresponding unmodulated algorithms for a variety of conditions.

关键词： adaptive estimation sonar tracking active sonar least mean squares methods computationally inexpensive algorithm Sonar and acoustic radar LMS-type algorithm Doppler shift linear regression problem sonar signal processing convergence narrowband signals target ranging filtering methods in signal processing high-resolution estimation Doppler shift estimation Interpolation and function approximation (numerical analysis) modulated Lagrange interpolation filter interpolation filtering theory convergence of numerical methods performance analysis target tracking delay estimation time delay estimation

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