通信系统 通信中的信号与噪声 英文版PDF电子书下载

Chapter 1 Introduction 1

1.1 Elements and Limitations of Communications Systems 2

Information，Messages，and Signals 2

Elements of a Communication System 3

Fundamental Limitations 5

1.2 Modulation and Coding 6

Modulation Methods 6

Modulation Benefits and Applications 7

Coding Methods and Benefits 10

1.3 Historical Perspective and Societal Impact 11

Historical Perspective 12

Societal Impact 14

1.4 Prospectus 15

Chapter 2 Signals and Spectra 17

2.1 Line Spectra and Fourier Series 19

Phasors and Line Spectra 19

Periodic Signals and Average Power 23

Fourier Series 25

Convergence Conditions and Gibbs Phenomenon 29

Parseval’s Power Theorem 31

Fourier Transforms 33

2.2 Fourier Transforms and Continuous Spectra(2.1) 33

Symmetric and Causal Signals 37

Rayleigh’s Energy Theorem 40

Duality Theorem 42

Transform Calculations 44

2.3 Time and Frequency Relations(2.2) 44

Superposition 45

Time Delay and Scale Change 45

Frequency Translation and Modulation 48

Differentiation and Integration 50

2.4 Convolution(2.3) 52

Convolution Integral 53

Convolution Theorems 55

2.5 Impulses and Transforms in the Limit (2.4) 58

Properties of the Unit Impulse 58

Impulses in Frequency 61

Step and Signum Functions 64

Impulses in Time 66

Chapter 3 Signal Transmission and Filtering 75

3.1 Response of LTI Systems(2.4) 76

Impulse Response and the Superposition Integral 77

Transfer Functions and Frequency Response 80

Block-Diagram Analysis 86

3.2 Signal Distortion in Transmission(3.1) 89

Distortionless Transmission 89

Linear Distortion 91

Equalization 94

Nonlinear Distortion and Companding 97

3.3 Transmission Loss and Decibels(3.2) 99

Power Gain 99

Transmission Loss and Repeaters 101

Fiber Optics 102

Radio Transmission 106

3.4 Filters and Filtering(3.3) 109

Ideal Filters 109

Bandlimiting and Timelimiting 111

Real Filters 112

Pulse Response and Risetime 116

3.5 Quadrature Filters and Hilbert Transforms(3.4) 120

3.6 Correlation and Spectral Density(3.3) 124

Correlation of Power Signals 124

Correlation of Energy Signals 127

Spectral Density Functions 130

Chapter 4 Linear CW Modulation 141

4.1 Bandpass Signals and Systems(3.4) 142

Analog Message Conventions 143

Bandpass Signals 144

Bandpass Transmission 147

4.2 Double-Sideband Amplitude Modulation(4.1) 152

AM Signals and Spectra 152

DSB Signals and Spectra 154

Tone Modulation and Phasor Analysis 157

Product Modulators 158

4.3 Modulators and Transmitters(4.2) 158

Square-Law and Balanced Modulators 160

Switching Modulators 162

4.4 Suppressed-Sideband Amplitude Modulation(3.5，4.3) 164

SSB Signals and Spectra 164

SSB Generation 167

VSB Signals and Spectra 170

4.5 Frequency Conversion and Demodulation(4.4) 172

Frequency Conversion 172

Synchronous Detection 173

Envelope Detection 176

Chapter 5 Exponential CW Modulation 183

PM and FM signals 184

5.1 Phase and Frequency Modulation(4.3) 184

Narrowband PM and FM 188

Tone Modulation 189

Multitone and Periodic Modulation 196

5.2 Transmission Bandwidth and Distortion(5.1) 199

Transmission Bandwidth Estimates 199

Linear Distortion 202

Nonlinear Distortion and Limiters 205

Direct FM and VCOs 208

5.3 Generation and Detection of FM and PM(4.5，5.2) 208

Phase Modulators and Indirect FM 209

Triangular-Wave FM 212

Frequency Detection 214

5.4 Interference(5.3) 219

Interfering Sinusoids 219

Deemphasis and Preemphasis Filtering 221

FM Capture Effect 224

Chapter 6 Sampling and Pulse Modulation 231

Chopper Sampling 232

6.1 Sampling Theory and Practice(4.2) 232

Ideal Sampling and Reconstruction 237

Practical Sampling and Aliasing 240

6.2 Pulse-Amplitude Modulation(6.1) 245

Flat-Top Sampling and PAM 245

6.3 Pulse-Time Modulation(6.2) 248

Pulse-Duration and Pulse-Position Modulation 248

PPM Spectral Analysis 251

Chapter 7 Analog Communication Systems 257

Superheterodyne Receivers 258

7.1 Receivers for CW Modulation(5.3) 258

Direct Conversion Receivers 262

Special-Purpose Receivers 262

Receiver Specifications 264

Scanning Spectrum Analyzers 265

7.2 Multiplexing Systems(5.3，6.1) 266

Frequency-Division Multiplexing 266

Quadrature-Carrier Multiplexing 271

Time-Division Multiplexing 272

Cross Talk and Guard Times 276

Comparison of TDM and FDM 277

PLL Operation and Lock-In 278

7.3 Phase-Lock Loops(7.1) 278

Synchronous Detection and Frequency Synthesizers 281

Linearized PLL Models and FM Detection 285

7.4 Television Systems(7.1) 286

Video Signals，Resolution，and Bandwidth 287

Monochrome Transmitters and Receivers 292

Color Television 294

HDTV 299

Chapter 8 Probability and Random Variables 311

Probabilities and Events 312

8.1 Probability and Sample Space 312

Sample Space and Probability Theory 313

Conditional Probability and Statistical Independence 317

8.2 Random Variables and Probability Functions(8.1) 320

Discrete Random Variables and CDFs 320

Continuous Random Variables and PDFs 323

Transformations of Random Variables 327

Joint and Conditional PDFs 329

8.3 Statistical Averages(2.3，8.2) 330

Means，Moments，and Expectation 331

Standard Deviation and Chebyshev’s Inequality 332

Multivariate Expectations 334

Characteristic Functions 336

8.4 Probability Models(8.3) 337

Binomial Distribution 337

Poisson Distribution 338

Gaussian PDF 339

Rayleigh PDF 342

Bivariate Gaussian Distribution 344

Chapter 9 Random Signals and Noise 351

9.1 Random Processes(3.6，8.4) 352

Ensemble Averages and Correlation Functions 353

Ergodic and Stationary Processes 357

Gaussian Processes 362

9.2 Random Signals(9.1) 362

Power Spectrum 362

Superposition and Modulation 367

Filtered Random Signals 368

9.3 Noise(9.2) 371

Thermal Noise and Available Power 372

White Noise and Filtered Noise 375

Noise Equivalent Bandwidth 378

System Measurements Using White Noise 380

9.4 Baseband Signal Transmission with Noise(9.3) 381

Additive Noise and Signal-to-Noise Ratios 382

Analog Signal Transmission 383

9.5 Baseband Pulse Transmission with Noise(9.4) 386

Pulse Measurements in Noise 386

Pulse Detection and Matched Filters 388

Chapter 10 Noise in Analog Modulation Systems 397

10.1 Bandpass Noise(4.4，9.2) 398

System Models 399

Quadrature Components 401

Envelope and Phase 403

Correlation Functions 404

10.2 Linear CW Modulation with Noise(10.2) 406

Synchronous Detection 407

Envelope Detection and Threshold Effect 409

10.3 Exponential CW Modulation with Noise(5.3，10.2) 412

Postdetection Noise 412

Destination S/N 416

FM Threshold Effect 418

Threshold Extension by FM Feedback 421

10.4 Comparison of CW Modulation Systems(9.4，10.3) 422

10.5 Phase-Lock Loop Noise Performance(7.3，10.1) 425

10.6 Analog Pulse Modulation with Noise(6.3，9.5) 426

Signal-to-Noise Ratios 426

False-Pulse Threshold Effect 429

Chapter 11 Baseband Digital Transmission 435

11.1 Digital Signals and Systems(9.1) 437

Digital PAM Signals 437

Transmission Limitations 440

Power Spectra of Digital PAM 443

Spectral Shaping by Precoding 446

Binary Error Probabilities 448

11.2 Noise and Errors(9.4，11.1) 448

Regenerative Repeaters 453

Matched Filtering 454

M-ary Error Probabilities 457

11.3 Bandlimited Digital PAM Systems(11.2) 461

Nyquist Pulse Shaping 461

Optimum Terminal Filters 464

Equalization 467

Correlative Coding 470

11.4 Synchronization Techniques(11.2) 476

Bit Synchronization 477

Scramblers and PN Sequence Generators 479

Frame Synchronization 484

Chapter 12 Digitization Techniques for Analog Messages and Networks 493

12.1 Pulse-Code Modulation(6.2，11.1) 495

PCM Generation and Reconstruction 495

Quantization Noise 499

Nonuniform Quantizing and Companding 501

12.2 PCM with Noise(11.2，12.1) 504

Decoding Noise 505

Error Threshold 507

PCM Versus Analog Modulation 508

12.3 Delta Modulation and Predictive Coding(12.2) 510

Delta Modulation 510

Delta-Sigma Modulation 516

Adaptive Delta Modulation 516

Differential PCM 518

LPC Speech Synthesis 520

12.4 Digital Audio Recording(12.3) 522

CD Recording 523

CD Playback 525

12.5 Digital Multiplexing(12.1) 526

Multiplexers and Hierarchies 527

Digital Subscriber Lines 530

Integrated Services Digital Network 532

Synchronous Optical Network 533

Data Multiplexers 535

12.6 Computer Networks(12.5) 537

Open Systems Interconnection 538

Transmission Control Protocol/Internet Protocol 539

Chapter 13 Channel Coding and Encryption 547

13.1 Error Detection and Correction(11.2) 549

Repetition and Parity-Check Codes 549

Interleaving 550

Code Vectors and Hamming Distance 552

FEC Systems 553

ARQ Systems 556

13.2 Linear Block Codes(13.1) 560

Matrix Representation of Block Codes 560

Syndrome Decoding 564

Cyclic Codes 567

M-ary Codes 573

13.3 Convolutional Codes(13.2) 574

Convolutional Encoding 574

Free Distance and Coding Gain 580

Decoding Methods 585

Turbo Codes 592

13.4 Data Encryption(13.1) 594

Data Encryption Standard 598

Rivest-Shamir-Adleman System 602

Chapter 14 Bandpass Digital Transmission 611

14.1 Digital CW Modulation(4.5，5.1，11.1) 612

Spectral Analysis of Bandpass Digital Signals 613

Amplitude Modulation Methods 614

Phase Modulation Methods 617

Frequency Modulation Methods 619

Minimum-Shift Keying 622

14.2 Coherent Binary Systems(11.2，14.1) 626

Optimum Binary Detection 626

Coherent OOK，BPSK，and FSK 631

Timing and Synchronization 633

14.3 Noncoherent Binary Systems(14.2) 634

Envelope of a Sinusoid Plus Bandpass Noise 634

Noncoherent OOK 636

Noncoherent FSK 638

Differentially Coherent PSK 640

14.4 Quadrature-Carrier and M-ary Systems(14.2) 644

Quadrature-Carrier Systems 644

M-ary PSK Systems 646

M-ary QAM Systems 650

Comparison of Digital Modulation Systems 653

14.5 Trellis-Coded Modulation 655

TCM Basics 656

Hard Versus Soft Decisions 664

Modems 665

Chapter 15 Spread Spectrum Systems 671

15.1 Direct Sequence Spread Spectrum(14.2) 672

DSS Signals 673

DSS Performance in the Presence of Interference 676

Multiple Access 678

15.2 Frequency Hop Spread Spectrum(15.1) 679

FH-SS Signals 680

FH-SS Performance in the Presence of Interference 682

15.3 Coding(15.1) 684

15.4 Synchronization(7.3) 689

Acquisition 689

Tracking 691

15.5 Wireless Telephone Systems(15.1) 692

Cellular Telephone Systems 693

Personal Communication Systems 693

Chapter 16 Information and Detection Theory 696

16.1 Information Measure and Source Coding(12.1) 699

Information Measure 700

Entropy and Information Rate 701

Coding for a Discrete Memoryless Channel 705

Predictive Coding for Sources with Memory 709

Mutual Information 713

16.2 Information Transmission on Discrete Channels(16.1) 713

Discrete Channel Capacity 717

Coding for the Binary Symmetric Channel 719

16.3 Continuous Channels and System Comparisons(16.2) 722

Continuous Information 722

Continuous Channel Capacity 725

Ideal Communication Systems 727

System Comparisons 731

16.4 Signal Space 735

Signals as Vectors 735

The Gram-Schmidt Procedure 738

16.5 Optimum Digital Detection(16.3，16.4) 740

Optimum Detection and MAP Receivers 741

Error Probabilities 747

Signal Selection and Orthogonal Signaling 751

Appendix：Circuit and System Noise(9.4) 760

Circuit and Device Noise 761

Amplifier Noise 768

System Noise Calculations 773

Cable Repeater Systems 777

Tables 780

T.1 Fourier Transforms 780

T.2 Fourier Series 782

T.3 Mathematical Relations 784

T.4 The Sinc Function 787

T.5 Probability Functions 788

T.6 Gaussian Probabilities 790

T.7 Glossary of Notation 792

Solutions to Exercises 794

Answers to Selected Problems 825

Supplementary Reading 832

References 835

Index 839