Deep Space Optical Communications

Transcription

1 Deep Space Optical Communications Edited by Hamid Hemmati WILEY- INTERSCIENCE A JOHN WILEY & SONS, INC., PUBLICATION

2 Table of Contents Foreword Preface Acknowledgments Contributors xvii xix xxiii xxv Chapter 1: Introduction 1 by James R. Lesh 1.1 Motivation for Increased Communications History of JPL Optical Communications Activities Component/Subsystem Technologies Laser Transmitters Spacecraft Telescopes Acquisition, Tracking, and Pointing Detectors Filters Error Correction Coding Flight Terminal Developments Optical Transceiver Package (OPTRANSPAC) Optical Communications Demonstrator (OCD) Lasercom Test and Evaluation Station (LTES) X2000 Flight Terminal International Space Station Flight Terminal Reception System and Network Studies Ground Telescope Cost Model Deep Space Optical Reception Antenna (DSORA) Deep Space Relay Satellite System (DSRSS) Studies Ground-Based Antenna Technology Study (GBATS) Advanced Communications Benefits Study (ACBS) Earth Orbit Optical Reception Terminal (EOORT) Study EOORT Hybrid Study Spherical Primary Ground Telescope Space-Based versus Ground-Based Reception Trades Atmospheric Transmission 34

3 VI 1.7 Background Studies Analysis Tools System-Level Studies Venus Radar Mapping (VRM) Mission Study Synthetic Aperture Radar-C (SIR-C) Freeflyer ER-2 to Ground Study Thousand Astronomical Unit (TAU) Mission and Interstellar Mission Studies System-Level Demonstrations Galileo Optical Experiment (GOPEX) Compensated Earth-Moon-Earth Retro-Reflector Laser Link (CEMERLL) Ground/Orbiter Lasercomm Demonstration (GOLD) Ground-Ground Demonstrations Other Telecommunication Functions Opto-Metric Navigation Light Science The Future Optical Communications Telescope Facility (OCTL) Unmanned Arial Vehicle (UAV)-Ground Demonstration Adaptive Optics Optical Receiver and Dynamic Detector Array Alternate Ground-Reception Systems Mars Laser Communication Demonstration Summary of Following Chapters 58 References 60 Chapter 2: Link and System Design 83 by Chien-Chung Chen 2.1 Overview of Deep-Space Lasercom Link Communications Link Design Link Equation and Receive Signal Power Optical-Receiver Sensitivity Photon Detection Sensitivity Modulation Format Background Noise Control Link Design Trades Operating Wavelength 98

4 Table of Contents vii Transmit Power and Size of Transmit and Receive Apertures Receiver Optical Bandwidth and Field of View versus Signal Throughput Modulation and Coding Communications Link Budget Link Availability Considerations Short-Term Data Outages Weather-Induced Outages Other Long-Term Outages Critical-Mission-Phase Coverage Beam Pointing and Tracking Downlink Beam Pointing Jitter Isolation and Rejection Precision Beam Pointing and Point Ahead Uplink Beam Pointing Pointing Acquisition Other Design Drivers and Considerations System Mass and Power Impact on Spacecraft Design Laser Safety Summary 115 References 118 Chapter 3: The Atmospheric Channel 121 by Abhijit Biswas and Sabino Piazzolla 3.1 Cloud Coverage Statistics National Climatic Data Center Data Set Single-Site and Two-Site Diversity Statistics Three-Site Diversity NCDC Analysis Conclusion Cloud Coverage Statistics by Satellite Data Observation Atmospheric Transmittance and Sky Radiance Atmospheric Transmittance Molecular Absorption and Scattering Aerosol Absorption and Scattering Atmospheric Attenuation Statistics Sky Radiance Sky Radiance Statistics Point Sources of Background Radiation 159

5 VIII 3.3 Atmospheric Issues on Ground Telescope Site Selection for an Optical Deep Space Network Optical Deep Space Network Data Rate/BER of a Mission Telescope Site Location Network Continuity and Peaks Laser Propagation Through the Turbulent Atmosphere Atmospheric Turbulence Atmospheric "Seeing" Effects Optical Scintillation or Irradiance Fluctuations Atmospheric Turbulence Induced Angle of Arrival 204 References 207 Chapter 4: Optical Modulation and Coding 215 by Samuel J. Dolinar, Jon Hamkins, Bruce E. Moision, and Victor A. Vilnrotter 4.1 Introduction Statistical Models for the Detected Optical Field Quantum Models of the Optical Field Quantization of the Electric Field The Coherent State Representation of a Single Field Mode Quantum Representation of Thermal Noise Quantum Representation of Signal Plus Thermal Noise Statistical Models for Direct Detection The Poisson Channel Model for Ideal Photodetectors or Ideal PMTs The Mclntyre-Conradi Model for APD Detectors The Webb, Mclntyre, and Conradi Approximation to the Mclntyre-Conradi Model The WMC Plus Gaussian Approximation Additive White Gaussian Noise Approximation Summary of Statistical Models Modulation Formats On-Off Keying (OOK) Pulse-Position Modulation (PPM) Differential PPM (DPPM) Overlapping PPM (OPPM) 236

6 Table of Contents ix Wavelength Shift Keying (WSK) Combined PPM and WSK Rate Limits Imposed by Constraints on Modulation Shannon Capacity Characterizing Capacity: Fixed Duration Edges Characterizing Capacity: Variable Duration Edges Characterizing Capacity: Probabilistic Characterization Characterizing Capacity: Energy Efficiency Constraints Dead Time Runlength Modulation Codes M-ary PPM with Deadtime A/-ary DPPM with Deadtime Synchronous Variable-Length Codes Performance of Uncoded Optical Modulations Direct Detection of OOK on the Poisson Channel Direct Detection of PPM Poisson Channel AWGN Channel Direct Detection of Combined PPM and WSK Performance of Modulations Using Receivers Based on Quantum Detection Theory Receivers Based on Quantum Detection Theory Performance of Representative Modulations Optical Channel Capacity Capacity of the PPM Channel: General Formulas Capacity of Soft-Decision PPM: Specific Channel Models Poisson Channel AWGN Channel Hard-Decision Versus Soft-Decision Capacity Losses Due to Using PPM Capacity of the Binary Channel with Quantum Detection Channel Codes for Optical Modulations Reed-Solomon Codes Turbo and Turbo-Like Codes for Optical Modulations Parallel Concatenated (Turbo) Codes Serially Concatenated Codes with Iterative Decoding 280

7 4.8 Performance of Coded Optical Modulations Parameter Selection Estimating Performance Reed-Solomon Codes Iterative Codes Achievable Data Rates Versus Average Signal Power 286 References 289 Chapter 5: Flight Transceiver 301 by Hamid Hemmati, Gerardo G. Ortiz, William T. Roberts, Malcolm W. Wright, and Shinhak Lee 5.1 Optomechanical Subsystem 301 by Hamid Hemmati Introduction Optical Beam Paths Optical Design Requirements, Design Drivers, and Challenges Optical Design Drivers and Approaches Transmit-Receive-Isolation Stray-Light Control Operation at Small Sun Angles Surface Cleanliness Requirements Transmission, Alignment, and Wavefront Quality Budgets Efficient Coupling of Lasers to Obscured Telescopes Axicon Optical Element Sub-Aperture Illumination Prism Beam Slicer Beam Splitter/Combiner Structure, Materials, and Structural Analysis Use of Fiber Optics Star-Tracker Optics for Acquisition and Tracking Thermal Management Optical System Design Example Afocal Fore-Optics Receiver Channel Stellar Reference Channel Align and Transmit Channels Folded Layouts Tolerance Sensitivity Analysis Thermal Soak Sensitivity Analysis Solid Model of System 329

8 Table of Contents xi 5.2 Laser Transmitter 331 by Hamid Hemmati Introduction Requirements and Challenges Candidate Laser Transmitter Sources Pulsed Laser Transmitters Fiber-Waveguide Amplifiers Bulk-Crystal Amplifiers Semiconductor Optical Amplifiers Lasers for Coherent Communications Laser Modulators Efficiency Laser Timing Jitter Control Jitter Control Options Redundancy Thermal Management Deep-Space Acquisition, Tracking, and Pointing 351 by Gerardo G. Ortiz and Shinhak Lee Unique Challenges of Deep Space Optical Beam Pointing State-of-the-Art ATP Performance Link Overview and System Requirements Pointing Requirement Pointing-Error Budget Allocations ATP System Pointing Knowledge Reference Sources Pointing System Architecture Design Considerations Cooperative Beacon (Ground Laser) Tracking Noncooperative Beacon Tracking Earth Tracker-Visible Spectrum Star Tracker Earth Tracker Long Wavelength Infrared Band ATP Technology Demonstrations Reduced Complexity ATP Architecture Centroiding Algorithms-Spot Model Method High Bandwidth, Windowing, CCD-Based Camera Accelerometer-Assisted Beacon Tracking Flight Qualification 419 by Hamid Hemmati, William T. Roberts, and Malcolm W. Wright Introduction Approaches to Flight Qualification 420

9 XII Flight Qualification of Electronics and Opto-Electronic Subsystem MIL-PRF MIL STD MIL STD Telcordia NASA Electronics Parts and Packaging (NEPP) Number of Test Units Space Environments Environmental Requirements Ionizing Radiation Vibration Environment Mechanical, Thermal, and Pyro Shock Environment Thermal Gradients Environment Depressurization Environment Electric and Magnetic Field Environment Outgassing Flight Qualification of Detectors Flight Qualification Procedures Detector Radiation Testing Flight Qualification of Laser Systems Past Laser Systems Flown in Space A.I2 Design of Semiconductor Lasers for High Reliability Applications Degradation Mechanisms Qualification Process for Lasers Flight Qualification of Optics 454 References 454 Chapter 6: Earth Terminal Architectures by Keith E. Wilson, Abhijit Biswas, Andrew A. Gray, Victor A. Vilnrotter, Chi-Wung Lau, Mera Srinivasan, and William H. Farr Introduction by Keith E. Wilson Single-Station Downlink Reception and Uplink Transmission 469 by Keith E. Wilson Introduction Deep-Space Optical Ground Receivers 470

10 Table of Contents xiii Mitigating Cloud Cover and Sky Background Effects at the Receiver Daytime Sky Background Effects Earth-Orbiting and Airborne Receivers Uplink Beacon and Command Techniques for Mitigating Atmospheric Effects Adaptive Optics Multiple-Beam Propagation Safe Laser Beam Propagation into Space Concept Validation Experiments Supporting Future Deep-Space Optical links Conclusion 514 Optical-Array Receivers for Deep-Space Communication 516 by Victor A. Vilnrotter, Chi-Wung Lau, and Meera Srinivasan.2.1 Introduction The Optical-Array Receiver Concept Aperture-Plane Expansions Array Receiver Performance Conclusions Photodetectors Single-Element Detectors 541 by Abhijit Biswas and William H. Farr Deep-Space Detector Requirements and Challenges Detector System Dependencies Detectors for Deep-Space Communications Focal-Plane Detector Arrays for Communication Through Turbulence 551 by Victor A. Vilnrotter and Meera Srinivasan Introduction Optical Direct Detection with Focal-Plane Arrays Numerical Results Summary And Conclusions Receiver Electronics by Andrew A. Gray, Victor A. Vilnrotter, and Meera Srinivasan Introduction Introduction to Discrete-Time Demodulator Architectures Discrete-Time Synchronization and Post-Detection Filtering Overview Discrete-Time Post-Detection Filtering 573

11 xiv Slot and Symbol Synchronization and Decision Processing Discrete-Time Demodulator Variations Discrete-Time Demodulator with Time-Varying Post-Detection Filter Parallel Discrete-Time Demodulator Architectures Asynchronous Discrete-Time Processing Parallel Discrete-Time Demodulator Architectures Simple Example Architecture Performance with a Simple Optical Channel Model Evolved Parallel Architectures Primary System Models and Parameters Conclusion and Future Work 618 References 626 Chapter 7: Future Prospects and Applications 643 by Hamid Hemmati and Abhijit Biswas 7.1 Current and Upcoming Projects in the United States, Europe, and Japan LUCE (Laser Utilizing Communications Experiment) Mars Laser-Communication Demonstrator (MLCD) Airborne and Spaceborne Receivers Advantages of Airborne and Spaceborne Receivers Disadvantages of Airborne and Spaceborne Receivers Airborne Terminals Balloons Airships Airplanes Spaceborne Receiver Terminals Alternative Receiver Sites Light Science Light-Propagation Experiments Occultation Experiments to Probe Planetary Atmospheres, Rings, Ionospheres, Magnetic Fields, and the Interplanetary Medium Atmospheric Occultations Ring-Investigation Experiments Enhanced Knowledge of Solar-System-Object Masses and Gravitational Fields, Sizes, Shapes, and Surface Features 652

12 Table of Contents xv Improved Knowledge of Solar-System Body Properties Optical Reference-Frame Ties Tests of the Fundamental Theories: General Relativity, Gravitational Waves, Unified Field Theories, Astrophysics, and Cosmology Tests of General Relativity and Unified Field Theories, Astrophysics, and Cosmology Effects of Charged Particles on Electromagnetic Wave Propagation, Including Test of 1/f Hypothesis Enhanced Solar-System Ephemerides Science Benefits of Remote Optical Tracking: Ephemeris Improvement Applications of Coherent Laser Communications Technology Conclusions 657 References 657