Engineering Satellite-Based Navigation and Timing

John W. Betz, PhD, is a Fellow of The MITRE Corporation and an internationally recognized expert in satellite-based navigation and timing. He is an innovator whose technical contributions and personal involvement have shaped the design of modernized GPS as well as other satnav systems. He is a sought-after speaker and instructor with multiple award-winning publications, and is a Fellow of the IEEE and the Institute of Navigation. His extensive knowledge, combined with his ability to provide a clearly structured and comprehensive depiction of all aspects of satnav engineering, promise to make this book the standard text and reference for this field.

Preface xv

Acknowledgments xvii

Useful Constants xix

List of Acronyms and Abbreviations xxi

About the Author xxvii

1 Introduction 1

1.1 Satnav Revolution 2

1.2 Basic Principles of Satnav 5

1.3 Satnav Attributes 12

1.4 Book Structure and How to Use This Book 12

1.5 More to Explore 14

Reference 15

Part I System and Signal Engineering 17

2 Satellite Orbits and Constellations 19

2.1 Kepler’s Laws 20

2.2 Orbital Deviations from Ideal 25

2.3 Constellations 26

2.4 Useful Geometry Calculations 30

2.5 Summary 35

Review Questions 35

References 36

3 Satnav Signals 37

3.1 Signals, Signal Processing, and Spreading Modulations 38

3.2 Effects of Doppler and of Lonospheric Propagation 59

3.3 Satnav Signal Characteristics 65

3.4 Satnav Signal Structure 86

3.5 Summary 92

Review Questions 92

References 99

4 Link Budgets 102

4.1 Free-Space Path Loss 103

4.2 Calculating Maximum and Minimum Specified Received Power in Signal Specifications 107

4.3 Terrestrial Link Budgets 112

4.4 Building Penetration and Foliage Losses 116

4.5 Summary 119

Review Questions 119

References 120

5 Correlator Output SNR, Effective C/N0, and I/S 122

5.1 Channel Model and Ideal Receiver Processing 122

5.2 Correlator Output SNR with No Interference 125

5.3 Correlator Output SNR with Interference: Spectral Separation Coefficients and Processing Gain 127

5.4 Effective C/N0 129

5.5 Interference-to-Signal Power Ratios and Effective C/N0 130

5.6 A Deeper Look at Spectral Separation Coefficients 130

5.7 Multiple Access Interference and Aggregate Gain of a Constellation 133

5.8 Summary 135

Review Questions 136

References 138

6 Error Sources and Error Characterization 139

6.1 Sources of Error in Satnav Positioning and Timing Calculation 140

6.2 Dilution of Precision and Error Measures 146

6.3 Positioning Errors for Standalone and Differential Satnav Receivers 150

6.4 Other Error Sources 152

6.5 Summary 153

Review Questions 154

References 155

Part II Satnav System Descriptions 157

7 Navstar Global Positioning System 163

7.1 GPS History and Plans 165

7.2 GPS Description 167

7.3 GPS Signals 168

7.4 Summary 196

Review Questions 197

References 198

8 Satellite-Based Augmentation Systems 201

8.1 SBAS History and Plans 202

8.2 SBAS Description 204

8.3 SBAS Signals 205

8.4 Summary 209

Review Questions 210

References 211

9 GLONASS 212

9.1 GLONASS History and Plans 213

9.2 GLONASS Description 214

9.3 GLONASS Signals 215

9.4 Summary 222

Review Questions 224

References 224

10 Galileo 226

10.1 Galileo History and Plans 227

10.2 Galileo Description 228

10.3 Galileo Signals 230

10.4 Summary 248

Review Questions 249

References 250

11 Beidou System 252

11.1 BDS History and Plans 253

11.2 BDS Description 254

11.3 BDS Signals 257

11.4 Summary 262

Review Questions 264

References 264

12 Quasi-Zenith Satellite System 266

12.1 QZSS History and Plans 267

12.2 QZSS Description 268

12.3 QZSS Signals 270

12.4 Summary 280

References 281

13 Indian Regional Satellite System 282

13.1 IRNSS History and Plans 283

13.2 IRNSS Description 283

13.3 IRNSS Signals 284

13.4 Summary 289

References 289

Part III Receiver Processing 291

14 Receiver Front End 297

14.1 Front-End Components 298

14.2 Front-End Noise Figure 321

14.3 Front-End Architectures and Frequency Plans 323

14.4 Summary 328

Review Questions 329

References 331

15 Analog-To-Digital Conversion 333

15.1 Introduction to Analog-to-Digital Conversion and Automatic Gain Control 334

15.2 Linear Analog-to-Digital Conversion 338

15.3 Precorrelator Analog-to-Digital Conversion—The Digitizing Correlator 340

15.4 Summary 362

Review Questions 362

References 363

16 Acquisition 364

16.1 Initial Conditions for Acquisition 367

16.2 Initial Synchronization Basics 370

16.3 Initial Synchronization Computation 383

16.4 Initial Synchronization Performance 392

16.5 Other Aspects of Acquisition 396

16.6 Summary 401

Review Questions 403

References 404

17 Discrete-Update Tracking Loops 406

17.1 Discrete-Update Tracking Loop Formulation 408

17.2 Discrete-Update Tracking Loop Design 412

17.3 Tracking Loop Characterization 416

17.4 Summary 426

References 427

18 Carrier Tracking and Data Demodulation 428

18.1 Signal Processing for Carrier Tracking 429

18.2 Frequency-Locked Loops 442

18.3 Costas Loops 447

18.4 Phase-Locked Loops 450

18.5 Data Message Demodulation 453

18.6 Summary 462

Review Questions 463

References 465

19 Code Tracking 467

19.1 Signal Processing for Code Tracking 468

19.2 Discriminators for Code Tracking 474

19.3 Carrier-Aided Code Tracking 480

19.4 Code Tracking Performance in White Noise 481

19.5 Code Tracking Performance in White Noise and Interference 489

19.6 Ambiguous Code Tracking 492

19.7 Summary 498

Appendix 19.A RMS Bandwidth 499

Review Questions 502

References 502

20 Position, Velocity, and Time Calculation 504

20.1 Forming Measurements 505

20.2 Reducing Pseudorange Errors 508

20.3 Standard Point Positioning 515

20.4 Blending Solutions from Multiple Satnav Systems 520

20.5 Velocity Calculation 522

20.6 Working with Disadvantaged Receivers 524

20.7 Precise Point Positioning 527

20.8 Integrity Monitoring: Receiver Autonomous Integrity Monitoring and Fault Detection and Exclusion 529

20.9 Summary 530

Review Questions 531

References 534

Part IV Specialized Topics 537

21 Interference 539

21.1 Interference Characteristics 540

21.2 Effects of Interference on Receiver Operation 541

21.3 Dealing with Interference 542

21.4 Summary 549

References 550

22 Multipath 551

22.1 Multipath Characteristics 552

22.2 Multipath Effects 556

22.3 Multipath Mitigation 560

22.4 Summary 567

References 568

23 Augmentations Using Differential Satnav 570

23.1 Overview of Differential Satnav 571

23.2 Code-Based Differential Systems 574

23.3 Carrier-Based Differential Systems 576

23.4 Summary 586

References 586

24 Assisted Satnav 588

24.1 Reducing IFU and ITU 590

24.2 Provision of Clock Corrections, Ephemeris, and Data Message Bits 591

24.3 Block Processing 592

24.4 Computing Pseudoranges and Position 592

24.5 Summary 593

Reference 594

25 Integrated Receiver Processing 595

25.1 Kalman Filter Overview 596

25.2 Loosely and Tightly Coupled Sensor-Integrated Satnav Processing 599

25.3 Standalone Vector Tracking 603

25.4 Ultratightly Coupled Sensor-Integrated Satnav Processing 605

25.5 Summary 606

References 607

A Theoretical Foundations 609

A.1 Some Useful Functions and Their Properties 610

A.2 Fourier Transforms 611

A.3 Signal Theory and Linear Systems Theory 611

A.4 Stochastic Processes 613

A.5 Some Results for Keyed Waveforms 615

A.6 Bandwidth Measures 619

A.7 Matrices and Matrix Algebra 621

A.8 Taylor Series and Linearization 623

A.9 Coordinate System Overview 624

References 625

Index 627