RANDOM SIGNALS ESTIMATION AND IDENTIFICATION ANALYSIS AND APPLICATIONS Nirode Mohanty The Aerospace Corporation Los Angeles, California Van Nostrand Reinhold Electrical/Computer Science and Engineering Series ~ VAN NOSTRAND REINHOLD COMPANY '~ New York _____ Copyright © 1986 by Van Nostrand Reinhold Company Inc. Softcover reprint of the hardcover I st edition 1986 Library of Congress Catalog Card Number: 85-12973 [SBN-13: 978-94-011-7043-7 e-ISBN-13: 978-94-011-7041-3 001: 10.100/978-94-011-7041-3 All rights reserved. No part of this work covered by the copyright hereon may be reproduced or used in any form or by any means-graphic, electronic, or mechanical, including photocopying, recording, taping, or information storage and retrieval systems-without permission of the publisher. Manufactured in the United States of America Published by Van Nostrand Reinhold Company Inc. 115 Fifth Avenue New York, New York 10003 Van Nostrand Reinhold Company Limited Molly Millars Lane Wokingham, Berkshire RG11 2PY, England Van Nostrand Reinhold 480 Latrobe Street Melbourne, Victoria 3000, Australia Macmillan of Canada Division of Gage Publishing Limited 164 Commander Boulevard Agincourt, Ontario MIS 3C7, Canada 15 14 13 1211 10 987654321 Library of Congress Cataloging in Publication Data Mohanty, Nirode. Random signals estimation and identification. (Van Nostrand Reinhold electrical/computer science and engineering series) Bibliography: p. Includes index. 1. Statistical communication theory. 2. Random noise theory. 3. Estimation theory. 1. Title. II. Series. TK5102.5.M64 1986 621.38'0436 85-12973 ISBN-13: 978-94-011-7043-7 To Dr. Richard Ernest Bellman, Professor of Mathematics, Electrical Engineering and Medicine University of Southern California Van Nostrand Reinhold Electrical/Computer Science and Engineering Series Sanjit Mitra -Series Editor HANDBOOK OF ELECTRONIC DESIGN AND ANALYSIS PROCEDURES USING PROGRAMMABLE CALCULATORS, by Bruce K. Murdock COMPILER DESIGN AND CONSTRUCTION, by Arthur B. Pyster SINUSOIDAL ANALYSIS AND MODELING OF WEAKLY NONLINEAR CIRCUITS, by Donald D. Weiner and John F. Spina APPLIED MULTIDIMENSIONAL SYSTEMS THEORY, by N. K. Bose MICROWAVE SEMICONDUCTOR ENGINEERING, by Joseph F. White INTRODUCTION TO QUARTZ CRYSTAL UNIT DESIGN, by Virgil E. Bottom DIGITAL IMAGE PROCESSING, by William B. 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Bloom DIGITAL COMMUNICATIONS, by Israel Korn RANDOM SIGNALS ESTIMATION AND IDENTIFICATION, by Nirode Mohanty Preface The techniques used for the extraction of information from received or ob served signals are applicable in many diverse areas such as radar, sonar, communications, geophysics, remote sensing, acoustics, meteorology, med ical imaging systems, and electronics warfare. The received signal is usually disturbed by thermal, electrical, atmospheric, channel, or intentional inter ferences. The received signal cannot be predicted deterministically, so that statistical methods are needed to describe the signal. In general, therefore, any received signal is analyzed as a random signal or process. The purpose of this book is to provide an elementary introduction to random signal analysis, estimation, filtering, and identification. The emphasis of the book is on the computational aspects as well as presentation of com mon analytical tools for systems involving random signals. The book covers random processes, stationary signals, spectral analysis, estimation, optimiz ation, detection, spectrum estimation, prediction, filtering, and identification. The book is addressed to practicing engineers and scientists. It can be used as a text for courses in the areas of random processes, estimation theory, and system identification by undergraduates and graduate students in engineer ing and science with some background in probability and linear algebra. Part of the book has been used by the author while teaching at State University of New York at Buffalo and California State University at Long Beach. Some of the algorithms presented in this book have been successfully applied to industrial projects. Random signal processes are dealt with in Chapter 1, with emphasis on Gaussian, Brownian, Poisson, and Markov processes. Mean square calculus and renewal theory are briefly discussed. Chapter 2 is devoted to stationary random processes along with spectral analysis, narrow-band processes, the Karhunen-Loeve expansion, entropy, zero crossing detectors, and nonlinear systems with random inputs. A comprehensive account of estimation theory is given in Chapter 3. Maximum-likelihood estimation, mean square estimation, maximum a priori estimation, the Cramer-Rao bound, and interval estimation are covered. Optimum filters including Wiener filtering are discussed for white and colored noise. Elements of signal detection are included in this chapter. Spectral estimation methods including the periodogram, autoregressive, maximum entropy, maximum likelihood, Pisarenko, and Prony methods are vii viii PREFACE discussed in Chapter 4. Adaptive spectral density estimation and cross spectral estimation are briefly described. Chapter 5 deals with prediction, filtering, and identification. Kalman filter ing, extended Kalman filtering, and recursive identification algorithms are given in this chapter. Each chapter contains a set of worked-out problems, exercises, and biblio graphic notes for further study. Appendix 1 contains a brief survey oflinear systems analysis, Z transforms, sampling theory, matrices, and orthogonal transforms. Elementary proba bility, random variables and distribution theory are treated in Appendix 2. Appendix 3 deals with the stochastic integral. Elements of Hilbert space are discussed in Appendix 4. The book concludes with a detailed bibliography and reference list. Many of the publications listed therein are suitable for further study. The author would like to thank the authors of the books and papers cited in the bibliography, which have greatly helped to write this book. He would also thank his friends and the management at The Aerospace Corporation for their encouragement and support. Readers are invited to send their com ments and corrections which will be appreciated very much. Los Angeles, California. Nirode Mohanty Notations Capital letters x, Y, Z etc. denote random variables or matrices. However, N is used also as a number of samples. Bold letters X, x, A, a etc. indicate vectors or matrices. x, y, z etc. stand for real numbers or dummy variables. P[X ~ x] = Probability of r.v. X is less than equal to x. X = (X1,XZ' ••• 'Xn) (n dimensional vector) Fx(x) = Probability distribution function of r.v. X, x is a real number ~ F(X) fx(x) = Probability density function of r.v. X, x is a real number ~ f(X) fx(xls) = Conditional probability density function of random vector X, x is a vector quantity given s ~ f(Xls) E(X) = Expected value of r.v. X, E is the expected operator Var(X) = Variance ofr.v. X. X(f) = ~(x(t)) ~ Fourier transform of x(t) X*(f) = Complex conjugate of X(f) X(s) = 2(x(t)) ~ Laplace transform of x(t) X(z) ~ Z transform of {Xd or {X(k)} A -1 = Inverse of matrix A X' = Transpose of vector X or matrix X ix Contents Preface / vii 1 Random Signals / 1 1.0 Introduction / 1 1.1 Characterization and Classification / 1 1.2 Correlation and Covariance Functions / 10 1.3 Gaussian Processes and Wiener Processes / 18 1.4 Poisson Process / 24 1.5 Mean Square Calculus / 34 1.6 Markov Process / 40 1.7 Renewal Process / 86 1.8 Bibliographical Notes / 98 Exercises / 98 2 Stationary Random Signals / 109 2.1 Introduction / 109 2.2 Linear Systems with Random Signal Input / 115 2.3 Cross Covariance and Coherence / 126 2.4 Narrowband Noise Process / 137 2.5 Orthogonal Expansion and Sampling / 141 2.6 Ergodicity and Entropy / 155 2.7 Zero Crossing Detectors / 170 2.8 Nonlinear Systems / 180 2.9 Bibliographical Notes / 197 Exercises / 197 3 Estimation, Optimization, and Detection / 212 3.0 Introduction / 212 3.1 Sampling Distribution / 212 3.2 Estimation of Parameter: Point Estimation / 217 3.3 Estimation Criteria / 223 3.4 Maximum Likelihood Estimation / 228 3.5 Linear Mean Square Estimation / 235 3.6 Method of Least Squares: Regression Models / 238 xi xii CONTENTS 3.7 Interval Estimation: Confidence Interval / 247 3.8 Cramer-Rao Inequality / 249 3.9 Estimation in Colored Noise / 259 3.10 Optimum Linear Filters / 266 3.11 Signal Detection / 292 3.12 Bibliographical Notes / 309 Exercises / 309 4 Spectral Analysis / 319 4.0 Introduction / 319 4.1 The Periodogram Approach / 319 4.2 Spectral Windows / 329 4.3 Autoregressive Method / 337 4.4 The Maximum Entropy Method / 343 4.5 Maximum Likelihood Estimator / 354 4.6 Pisarenko and Prony Methods / 359 4.7 Adaptive Lattices Method / 369 4.8 Cross Spectral Estimation / 387 4.9 Bibliographical Notes / 395 Exercises / 396 5 Prediction, Filtering, and Identification / 412 5.0 Introduction / 412 5.1 State Space Representation / 413 5.2 The Innovation Process / 457 5.3 Linear Prediction and Kalman Filtering / 476 5.4 Smoothing / 498 5.5 Extended Kalman Filtering / 504 5.6 System Identification / 509 5.7 Bibliographical Notes / 526 Exercises / 527 Appendix 1. Linear Systems Analysis / 549 Appendix 2. Probability / 566 Appendix 3. Stochastic Integrals / 589 Appendix 4. Hilbert Space / 598 Bibliography / 609 Index / 619