Library of Congress Cataloging-in-Publication Data Advanced signal processing handbook : theory and implementation for radar, sonar, and medical imaging real-time systems / edited by Stergios Stergiopoulos. p. cm. — (Electrical engineering and signal processing series) Includes bibliographical references and index. ISBN 0-8493-3691-0 (alk. paper) 1. Signal processing—Digital techniques. 2. Diagnostic imaging—Digital techniques. 3. Image processing—Digital techniques. I. Stergiopoulos, Stergios. II. Series. TK5102.9 .A383 2000 621.382′2—dc21 00-045432 CIP This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. 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Specific permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. © 2001 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 0-8493-3691-0 Library of Congress Card Number 00-045432 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper Preface Recent advances in digital signal processing algorithms and computer technology have combined to provide the ability to produce real-time systems that have capabilities far exceeding those of a few years ago. The writing of this handbook was prompted by a desire to bring together some of the recent theoretical developments on advanced signal processing, and to provide a glimpse of how modern technology can be applied to the development of current and next-generation active and passive real- time systems. The handbook is intended to serve as an introduction to the principles and applications of advanced signal processing. It will focus on the development of a generic processing structure that exploits the great degree of processing concept similarities existing among the radar, sonar, and medical imaging systems. A high-level view of the above real-time systems consists of a high-speed Signal Processor to provide mainstream signal processing for detection and initial parameter estimation, a Data Manager which supports the data and information processing functionality of the system, and a Display Sub- System through which the system operator can interact with the data structures in the data manager to make the most effective use of the resources at his command. The Signal Processor normally incorporates a few fundamental operations. For example, the sonar and radar signal processors include beamforming, “matched” filtering, data normalization, and image pro- cessing. The first two processes are used to improve both the signal-to-noise ratio (SNR) and parameter estimation capability through spatial and temporal processing techniques. Data normalization is required to map the resulting data into the dynamic range of the display devices in a manner which provides a CFAR (constant false alarm rate) capability across the analysis cells. The processing algorithms for spatial and temporal spectral analysis in real-time systems are based on conventional FFT and vector dot product operations because they are computationally cheaper and more robust than the modern non-linear high resolution adaptive methods. However, these non-linear algorithms trade robustness for improved array gain performance. Thus, the challenge is to develop a concept which allows an appropriate mixture of these algorithms to be implemented in practical real-time systems. The non-linear processing schemes are adaptive and synthetic aperture beamformers that have been shown experimentally to provide improvements in array gain for signals embedded in partially correlated noise fields. Using system image outputs, target tracking, and localization results as performance criteria, the impact and merits of these techniques are contrasted with those obtained using the conventional processing schemes. The reported real data results show that the advanced processing schemes provide improvements in array gain for signals embedded in anisotropic noise fields. However, the same set of results demonstrates that these processing schemes are not adequate enough to be considered as a replacement for conventional processing. This restriction adds an additional element in our generic signal processing structure, in that the conventional and the advanced signal processing schemes should run in parallel in a real-time system in order to achieve optimum use of the advanced signal processing schemes of this study. ©2001 CRC Press LLC The handbook also includes a generic concept for implementing successfully adaptive schemes with near-instantaneous convergence in 2-dimensional (2-D) and 3-dimensional (3-D) arrays of sensors, such as planar, circular, cylindrical, and spherical arrays. It will be shown that the basic step is to minimize the number of degrees of freedom associated with the adaptation process. This step will minimize the adaptive scheme’s convergence period and achieve near-instantaneous convergence for integrated active and passive sonar applications. The reported results are part of a major research project, which includes the definition of a generic signal processing structure that allows the implementation of adaptive and synthetic aperture signal processing schemes in real-time radar, sonar, and medical tomography (CT, MRI, ultrasound) systems that have 2-D and 3-D arrays of sensors. The material in the handbook will bridge a number of related fields: detection and estimation theory; filter theory (Finite Impulse Response Filters); 1-D, 2-D, and 3-D sensor array processing that includes conventional, adaptive, synthetic aperture beamforming and imaging; spatial and temporal spectral analysis; and data normalization. Emphasis will be placed on topics that have been found to be particularly useful in practice. These are several interrelated topics of interest such as the influence of medium on array gain system performance, detection and estimation theory, filter theory, space-time processing, conventional, adaptive processing, and model-based signal processing concepts. Moveover, the system concept similarities between sonar and ultrasound problems are identified in order to exploit the use of advanced sonar and model-based signal processing concepts in ultrasound systems. Furthermore, issues of information post-processing functionality supported by the Data Manager and the Display units of real-time systems of interest are addressed in the relevant chapters that discuss nor- malizers, target tracking, target motion analysis, image post-processing, and volume visualization methods. The presentation of the subject matter has been influenced by the authors’ practical experiences, and it is hoped that the volume will be useful to scientists and system engineers as a textbook for a graduate course on sonar, radar, and medical imaging digital signal processing. In particular, a number of chapters summarize the state-of-the-art application of advanced processing concepts in sonar, radar, and medical imaging X-ray CT scanners, magnetic resonance imaging, and 2-D and 3-D ultrasound systems. The focus of these chapters is to point out their applicability, benefits, and potential in the sonar, radar, and medical environments. Although an all-encompassing general approach to a subject is mathematically elegant, practical insight and understanding may be sacrificed. To avoid this problem and to keep the handbook to a reasonable size, only a modest introduction is provided. In consequence, the reader is expected to be familiar with the basics of linear and sampled systems and the principles of probability theory. Furthermore, since modern real-time systems entail sampled signals that are digitized at the sensor level, our signals are assumed to be discrete in time and the subsystems that perform the processing are assumed to be digital. It has been a pleasure for me to edit this book and to have the relevant technical exchanges with so many experts on advanced signal processing. I take this opportunity to thank all authors for their responses to my invitation to contribute. I am also greatful to CRC Press LLC and in particular to Bob Stern, Helena Redshaw, Naomi Lynch, and the staff in the production department for their truly professional cooperation. Finally, the support by the European Commission is acknowledged for awarding Professor Uzunoglu and myself the Fourier Euroworkshop Grant (HPCF-1999-00034) to organize two workshops that enabled the contributing authors to refine and coherently integrate the material of their chapters as a handbook on advanced signal processing for sonar, radar, and medical imaging system applications. Stergios Stergiopoulos ©2001 CRC Press LLC Editor Stergios Stergiopoulos received a B.Sc. degree from the University of Athens in 1976 and the M.S. and Ph.D. degrees in geophysics in 1977 and 1982, respectively, from York University, Toronto, Canada. Presently he is an Adjunct Professor at the Department of Electrical and Computer Engineering of the University of Western Ontario and a Senior Defence Scientist at Defence and Civil Institute of Environ- mental Medicine (DCIEM) of the Canadian DND. Prior to this assignment and from 1988 and 1991, he was with the SACLANT Centre in La Spezia, Italy, where he performed both theoretical and experimental research in sonar signal processing. At SACLANTCEN, he developed jointly with Dr. Sullivan from NUWC an acoustic synthetic aperture technique that has been patented by the U.S. Navy and the Hellenic Navy. From 1984 to 1988 he developed an underwater fixed array surveillance system for the Hellenic Navy in Greece and there he was appointed senior advisor to the Greek Minister of Defence. From 1982 to 1984 he worked as a research associate at York University and in collaboration with the U.S. Army Ballistic Research Lab (BRL), Aberdeen, MD, on projects related to the stability of liquid-filled spin stabilized projectiles. In 1984 he was awarded a U.S. NRC Research Fellowship for BRL. He was Associate Editor for the IEEE Journal of Oceanic Engineering and has prepared two special issues on Acoustic Synthetic Aperture and Sonar System Technology. His present interests are associated with the imple- mentation of non-conventional processing schemes in multi-dimensional arrays of sensors for sonar and medical tomography (CT, MRI, ultrasound) systems. His research activities are supported by Canadian- DND Grants, by Research and Strategic Grants (NSERC-CANADA) ($300K), and by a NATO Collabo- rative Research Grant. Recently he has been awarded with European Commission-ESPRIT/IST Grants as technical manager of two projects entitled “New Roentgen” and “MITTUG.” Dr. Stergiopoulos is a Fellow of the Acoustical Society of America and a senior member of the IEEE. He has been a consultant to a number of companies, including Atlas Elektronik in Germany, Hellenic Arms Industry, and Hellenic Aerospace Industry. ©2001 CRC Press LLC Contributors Dimos Baltas Konstantinos K. Delibasis Simon Haykin Department of Medical Physics Institute of Communication Communications Research and Engineering and Computer Systems Laboratory Strahlenklinik, Städtische National Technical University McMaster University Kliniken Offenbach of Athens Hamilton, Ontario, Canada Offenbach, Germany Athens, Greece Grigorios Karangelis Institute of Communication Amar Dhanantwari Department of Cognitive and Computer Systems Defence and Civil Institute of Computing and Medical National Technical University Environmental Medicine Imaging of Athens Toronto, Ontario, Canada Fraunhofer Institute Athens, Greece for Computer Graphics Reza M. Dizaji Darmstadt, Germany Klaus Becker School of Earth and Ocean Sciences FGAN Research Institute University of Victoria R. Lynn Kirlin for Communication, Victoria, British Columbia, Canada School of Earth and Ocean Sciences Information Processing, University of Victoria and Ergonomics (FKIE) Donal B. Downey Victoria, British Columbia, Canada Wachtberg, Germany The John P. Robarts Research Institute Wolfgang Koch James V. Candy University of Western Ontario FGAN Research Institute Lawrence Livermore National London, Ontario, Canada for Communciation, Laboratory Information Processing, University of California Geoffrey Edelson and Ergonomics (FKIE) Livermore, California, U.S.A. Advanced Systems and Technology Wachtberg, Germany Sanders, A Lockheed G. Clifford Carter Martin Company Christos Kolotas Naval Undersea Warfare Center Nashua, New Hampshire, U.S.A. Department of Medical Physics Newport, Rhode Island, U.S.A. and Engineering Aaron Fenster Strahlenklinik, Städtische N. Ross Chapman The John P. Robarts Kliniken Offenbach School of Earth and Ocean Sciences Research Institute Offenbach, Germany University of Victoria University of Western Ontario Victoria, British Columbia, Canada London, Ontario, Canada Harry E. Martz, Jr. Lawrence Livermore Ian Cunningham Dimitris Hatzinakos National Laboratory The John P. Robarts Department of Electrical University of California Research Institute and Computer Engineering Livermore, California, U.S.A. University of Western Ontario University of Toronto London, Ontario, Canada Toronto, Ontario, Canada ©2001 CRC Press LLC George K. Matsopoulos Arnulf Oppelt Daniel J. Schneberk Institute of Communication Siemens Medical Engineering Group Lawrence Livermore and Computer Systems Erlangen, Germany National Laboratory National Technical University University of California of Athens Kostantinos N. Plataniotis Livermore, California, U.S.A. Athens, Greece Department of Electrical and Computer Engineering Stergios Stergiopoulos Charles A. McKenzie University of Toronto Defence and Civil Institute Cardiovascular Division Toronto, Ontario, Canada of Environmental Medicine Beth Israel Deaconess Medical Center Toronto, Ontario, Canada and Harvard Medical School Andreas Pommert Department of Electrical Boston, Massachusetts, U.S.A. Institute of Mathematics and and Computer Engineering Computer Science in Medicine University of Western Ontario Bernard E. McTaggart University Hospital Eppendorf London, Ontario, Canada Naval Undersea Warfare Center Hamburg, Germany (retired) Edmund J. Sullivan Newport, Rhode Island, U.S.A. Frank S. Prato Naval Undersea Warfare Center Lawson Research Institute Newport, Rhode Island, U.S.A. Sanjay K. Mehta and Department Naval Undersea Warfare Center of Medical Biophysics Rebecca E. Thornhill Newport, Rhode Island, U.S.A. University of Western Ontario Lawson Research Institute and London, Ontario, Canada Department of Medical Natasa Milickovic Biophysics Department of Medical Physics John M. Reid University of Western Ontario and Engineering Department of Biomedical London, Ontario, Canada Strahlenklinik, Städtische Engineering Kliniken Offenbach Drexel University Nikolaos Uzunoglu Offenbach, Germany Philadelphia, Pennsylvania, U.S.A. Department of Electrical Department of Radiology and Computer Engineering Gerald R. Moran Thomas Jefferson University National Technical University Lawson Research Institute and Philadelphia, Pennsylvania, U.S.A. of Athens Department of Medical Athens, Greece Biophysics Department of Bioengineering University of Western Ontario University of Washington Nikolaos Zamboglou London, Ontario, Canada Seattle, Washington, U.S.A. Department of Medical Physics and Engineering Nikolaos A. Georgios Sakas Strahlenklinik, Städtische Mouravliansky Department of Cognitive Computing Kliniken Offenbach Institute of Communication and Medical Imaging Offenbach, Germany and Computer Systems Fraunhofer Institute National Technical University for Computer Graphics Institute of Communication of Athens Darmstadt, Germany and Computer Systems Athens, Greece National Technical University of Athens Athens, Greece ©2001 CRC Press LLC Dedication To my lifelong companion Vicky, my son Steve, and my daughter Erene ©2001 CRC Press LLC Contents 1 Signal Processing Concept Similarities among Sonar, Radar, and Medical Imaging Systems Stergios Stergiopoulos 1.1 Introduction 1.2 Overview of a Real-Time System 1.3 Signal Processor 1.4 Data Manager and Display Sub-System SECTION I General Topics on Signal Processing 2 Adaptive Systems for Signal Process Simon Haykin 2.1 The Filtering Problem 2.2 Adaptive Filters 2.3 Linear Filter Structures 2.4 Approaches to the Development of Linear Adaptive Filtering Algorithms 2.5 Real and Complex Forms of Adaptive Filters 2.6 Nonlinear Adaptive Systems: Neural Networks 2.7 Applications 2.8 Concluding Remarks 3 Gaussian Mixtures and Their Applications to Signal Processing Kostantinos N. Plataniotis and Dimitris Hatzinakos 3.1 Introduction 3.2 Mathematical Aspects of Gaussian Mixtures 3.3 Methodologies for Mixture Parameter Estimation 3.4 Computer Generation of Mixture Variables 3.5 Mixture Applications 3.6 Concluding Remarks 4 Matched Field Processing — A Blind System Identification Technique N. Ross Chapman, Reza M. Dizaji, and R. Lynn Kirlin 4.1 Introduction 4.2 Blind System Identification 4.3 Cross-Relation Matched Field Processor 4.4 Time-Frequency Matched Field Processor ©2001 CRC Press LLC