Tài liệu Introduction to analog and digital communication - simon haykin, michael mohe

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For more information on what WileyPLUS can do to help you and your students reach their potential, please visit www.wiley.com/college/wileyplus. 76% of students surveyed said it made them better prepared for tests. * *Based on a survey of 972 student users of WileyPLUS Introduction to Analog and Digital Communications This page intentionally left blank Introduction to Analog and Digital Communications Second Edition Simon Haykin McMaster University, Hamilton, Ontario, Canada Michael Moher Space-Time DSP, Ottawa, Ontario, Canada JOHN WILEY & SONS, INC. ASSOCIATE PUBLISHER Dan Sayre SENIOR ACQUISITIONS EDITOR AND PROJECT MANAGER PROJECT EDITOR Gladys Soto MARKETING MANAGER Phyllis Diaz Cerys EDITORIAL ASSISTANT Dana Kellog SENIOR PRODUCTION EDITOR Lisa Wojcik MEDIA EDITOR Stefanie Liebman DESIGNER Hope Miller SENIOR ILLUSTRATION EDITOR Sigmund Malinowski COVER IMAGE © Photodisc/Getty Images Catherine Shultz This book was set in Quark by Prepare Inc. and printed and bound by Hamilton Printing. The cover was printed by Phoenix Color Corp. This book is printed on acid free paper. ⬁ Copyright © 2007 John Wiley & Sons, Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978)750-8400, fax (978)646-8600, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, (201)7486011, fax (201)748-6008, or online at http://www.wiley.com/go/permissions. To order books or for customer service please, call 1-800-CALL WILEY (225-5945). ISBN-13 978-0-471-43222-7 ISBN-10 0-471-43222-9 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 To the 20th Century pioneers in communications who, through their mathematical theories and ingenious devices, have changed our planet into a global village This page intentionally left blank PREFACE An introductory course on analog and digital communications is fundamental to the undergraduate program in electrical engineering. This course is usually offered at the junior level. Typically, it is assumed that the student has a background in calculus, electronics, signals and systems, and possibly probability theory. Bearing in mind the introductory nature of this course, a textbook recommended for the course must be easy to read, accurate, and contain an abundance of insightful examples, problems, and computer experiments. These objectives of the book are needed to expedite learning the fundamentals of communication systems at an introductory level and in an effective manner. This book has been written with all of these objectives in mind. Given the mathematical nature of communication theory, it is rather easy for the reader to lose sight of the practical side of communication systems. Throughout the book, we have made a special effort not to fall into this trap. We have done this by moving through the treatment of the subject in an orderly manner, always trying to keep the mathematical treatment at an easy-to-grasp level and also pointing out practical relevance of the theory wherever it is appropriate to do so. Structural Philosophy of the Book To facilitate and reinforce learning, the layout and format of the book have been structured to do the following: • Provide motivation to read the book and learn from it. • Emphasize basic concepts from a “systems” perspective and do so in an orderly manner. • Wherever appropriate, include examples and computer experiments in each chapter to illustrate application of the pertinent theory. • Provide drill problems following the discussion of fundamental concepts to help the user of the book verify and master the concepts under discussion. • Provide additional end-of-chapter problems, some of an advanced nature, to extend the theory covered in the text. Organization of the book 1. Motivation Before getting deeply involved in the study of analog and digital communications, it is imperative that the user of the book be motivated to use the book and learn from it. To this end, Chapter 1 begins with a historical background of communication systems and important applications of the subject. 2. Modulation Theory Digital communication has overtaken analog communications as the dominant form of communications. Although, indeed, these two forms of communications work in different ways, modulation theory is basic to them both. Moreover, it is easiest to understand this important subject by first covering its fundamental concepts applied to analog communications and then moving on to digital communications. Moreover, amplitude modulation is simpler than angle modulation to present. One other highly relevant point is the fact that to understand modulation theory, it is important that Fourier theory be mastered first. With these points in mind, Chapters 2 through 7 are organized as follows: ix x APPENDIX 1  POWER RATIOS AND DECIBEL • Chapter 2 is devoted to reviewing the Fourier representation of signals and systems. • Chapters 3 and 4 are devoted to analog communications, with Chapter 3 covering amplitude modulation and Chapter 4 covering angle modulation. • Chapter 5 on pulse modulation covers the concepts pertaining to the transition from analog to digital communications. • Chapters 6 and 7 are devoted to digital communications, with Chapter 6 covering baseband data transmission and Chapter 7 covering band-pass data transmission. 3. Probability Theory and Signal Detection Just as Fourier analysis is fundamental to modulation theory, probability theory is fundamental to signal detection and receiver performance evaluation in the presence of additive noise. Since probability theory is not critical to the understanding of modulation, we have purposely delayed the review of probability theory, random signals, and noise until Chapter 8. Then, with a good understanding of modulation theory applied to analog and digital communications and relevant concepts of probability theory and probabilistic models at hand, the stage is set to revisit analog and digital communication receivers, as summarized here: • Chapter 9 discusses noise in analog communications. • Chapter 10 discusses noise in digital communications. Because analog and digital communications operate in different ways, it is natural to see some fundamental differences in treating the effects of noise in these two chapters. 4. Noise The introductory study of analog and digital communications is completed in Chapter 11. This chapter illustrates the roles of modulation and noise in communication systems by doing four things: • First, the physical sources of noise, principally, thermal noise and shot noise, are described. • Second, the metrics of noise figure and noise temperature are introduced. • Third, how propagation affects the signal strength in satellite and terrestrial wireless communications is explained. • Finally, we show how the signal strength and noise calculations may be combined to provide an estimate of the signal-to-noise ratio, the fundamental figure of merit for communication systems. 5. Theme Examples In order to highlight important practical applications of communication theory, theme examples are included wherever appropriate. The examples are drawn from the worlds of both analog and digital communications. 6. Appendices To provide back-up material for the text, eight appendices are included at the end of the book, which cover the following material in the order presented here: • Power ratios and the decibel • Fourier series • Bessel functions • The Q-function and its relationship to the error function • Schwarz’s inequality • Mathematical tables xi Preface • Matlab scripts for computer experiments to problems in Chapters 7–10 • Answers to drill problems 7. Footnotes, included throughout the book, are provided to help the interested reader to pursue selected references for learning advanced material. 8. Auxiliary Material The book is essentially self-contained. A glossary of symbols and a bibliography are provided at the end of the book. As an aid to the teacher of the course using the book, a detailed Solutions Manual for all the problems, those within the text and those included at the end of chapters, will be made available through the publisher: John Wiley and Sons. How to Use the Book The book can be used for an introductory course on analog and digital communications in different ways, depending on the background of the students and the teaching interests and responsibilities of the professors concerned. Here are two course models of how this may be done: COURSE MODEL A: FULL TWO-SEMESTER COURSE (A.1) The first semester course on modulation theory consists of Chapters 2 through 7, inclusive. (A.2) The second semester course on noise in communication systems consists of Chapters 8 through 11, inclusive. COURSE MODEL B: TWO SEMESTER COURSES, OTHER ON DIGITAL ONE ON ANALOG AND THE (B.1) The first course on analog communications begins with review material from Chapter 2 on Fourier analysis, followed by Chapter 3 on amplitude modulation and Chapter 4 on angle modulation, then proceeds with a review of relevant parts of Chapter 8 on noise, and finally finishes with Chapter 9 on noise in analog communications. (B.2) The second course on digital communications starts with Chapter 5 on pulse modulation, followed by Chapter 6 on baseband data transmission and Chapter 7 on digital modulation techniques, then proceeds with review of relevant aspects of probability theory in Chapter 8, and finally finishes with Chapter 10 on noise in digital communications. Simon Haykin Ancaster, Ontario, Canada Michael Moher Ottawa, Ontario, Canada This page intentionally left blank ACKNOWLEDGEMENTS The authors would like to express their deep gratitude to • Lily Jiang, formerly of McMaster University for her help in performing many of the computer experiments included in the text. • Wei Zhang, for all the help, corrections, and improvements she has made to the text. They also wish to thank Dr. Stewart Crozier and Dr. Paul Guinand, both of the Communications Research Centre, Ottawa, for their inputs on different parts of the book. They are also indebted to Catherine Fields Shultz, Senior Acquisitions Editor and Product Manager (Engineering and Computer Science) at John Wiley and Sons, Bill Zobrist formerly of Wiley, and Lisa Wojcik, Senior Production Editor at Wiley, for their guidance and dedication to the production of this book. Last but by no means least, they are grateful to Lola Brooks, McMaster University, for her hard work on the preparation of the manuscript and related issues to the book. xiii This page intentionally left blank CONTENTS Chapter 1 Introduction 1 1.1 Historical Background 1 1.2 Applications 1.3 Primary Resources and Operational Requirements 1.4 Underpinning Theories of Communication Systems 1.5 Concluding Remarks 4 13 14 16 Chapter 2 Fourier Representation of Signals and Systems 2.1 The Fourier Transform 2.2 Properties of the Fourier Transform 2.3 The Inverse Relationship Between Time and Frequency 2.4 Dirac Delta Function 2.5 Fourier Transforms of Periodic Signals 2.6 Transmission of Signals Through Linear Systems: Convolution Revisited 52 2.7 Ideal Low-pass Filters 2.8 Correlation and Spectral Density: Energy Signals 2.9 Power Spectral Density 2.10 Numerical Computation of the Fourier Transform 2.11 Theme Example: Twisted Pairs for Telephony 2.12 Summary and Discussion Additional Problems Advanced Problems 18 19 25 39 42 50 60 70 79 81 89 90 91 98 Chapter 3 Amplitude Modulation 100 3.1 Amplitude Modulation 101 3.2 Virtues, Limitations, and Modifications of Amplitude Modulation 3.3 Double Sideband-Suppressed Carrier Modulation 3.4 Costas Receiver 113 114 120 xv xvi APPENDIX 1  POWER RATIOS AND DECIBEL 3.5 Quadrature-Carrier Multiplexing 3.6 Single-Sideband Modulation 3.7 Vestigial Sideband Modulation 3.8 Baseband Representation of Modulated Waves and Band-Pass Filters 137 3.9 Theme Examples 3.10 Summary and Discussion Additional Problems Advanced Problems 121 123 130 142 147 148 150 Chapter 4 Angle Modulation 152 4.1 Basic Definitions 4.2 Properties of Angle-Modulated Waves 4.3 Relationship between PM and FM Waves 4.4 Narrow-Band Frequency Modulation 4.5 Wide-Band Frequency Modulation 4.6 Transmission Bandwidth of FM Waves 4.7 Generation of FM Waves 4.8 Demodulation of FM Signals 4.9 Theme Example: FM Stereo Multiplexing 4.10 Summary and Discussion Additional Problems Advanced Problems 153 154 159 160 164 170 172 174 182 184 185 187 Chapter 5 Pulse Modulation: Transition from Analog to Digital Communications 190 5.1 Sampling Process 191 5.2 Pulse-Amplitude Modulation 5.3 Pulse-Position Modulation 5.4 Completing the Transition from Analog to Digital 5.5 Quantization Process 5.6 Pulse-Code Modulation 198 202 205 206 203 xvii Contents 5.7 Delta Modulation 5.8 Differential Pulse-Code Modulation 5.9 Line Codes 5.10 Theme Examples 5.11 Summary and Discussion Additional Problems Advanced Problems 211 216 219 220 225 226 228 Chapter 6 Baseband Data Transmission 231 6.1 Baseband Transmission of Digital Data 232 6.2 The Intersymbol Interference Problem 233 6.3 The Nyquist Channel 6.4 Raised-Cosine Pulse Spectrum 6.5 Baseband Transmission of M-ary Data 6.6 The Eye Pattern 6.7 Computer Experiment: Eye Diagrams for Binary and Quaternary Systems 249 6.8 Theme Example: Equalization 6.9 Summary and Discussion Additional Problems Advanced Problems 235 238 245 246 251 256 257 259 Chapter 7 Digital Band-Pass Modulation Techniques 7.1 Some Preliminaries 262 7.2 Binary Amplitude-Shift Keying 7.3 Phase-Shift Keying 7.4 Frequency-Shift Keying 7.5 Summary of Three Binary Signaling Schemes 7.6 Noncoherent Digital Modulation Schemes 7.7 M-ary Digital Modulation Schemes 7.8 Mapping of Digitally Modulated Waveforms onto Constellations of Signal Points 299 265 270 281 289 291 295 262 xviii APPENDIX 1  POWER RATIOS AND DECIBEL 7.9 Theme Examples 7.10 Summary and Discussion Additional Problems Advanced Problems 302 307 309 310 Computer Experiments 312 Chapter 8 Random Signals and Noise 313 8.1 Probability and Random Variables 8.2 Expectation 8.3 Transformation of Random Variables 8.4 Gaussian Random Variables 330 8.5 The Central Limit Theorem 333 8.6 Random Processes 8.7 Correlation of Random Processes 8.8 Spectra of Random Signals 8.9 Gaussian Processes 8.10 White Noise 8.11 Narrowband Noise 8.12 Summary and Discussion Additional Problems Advanced Problems 314 326 329 335 338 343 347 348 352 356 357 361 Computer Experiments 363 Chapter 9 Noise in Analog Communications 364 9.1 Noise in Communication Systems 365 9.2 Signal-to-Noise Ratios 9.3 Band-Pass Receiver Structures 9.4 Noise in Linear Receivers Using Coherent Detection 9.5 Noise in AM Receivers Using Envelope Detection 9.6 Noise in SSB Receivers 9.7 Detection of Frequency Modulation (FM) 366 369 377 380 370 373
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