Laser Space Communications (Artech House Space Technology and Applications)

212 Pages·2006·4.13 MB·English

by  David G. Aviv

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Laser Space Communications
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For a complete listing of the Artech House Space Technology and Applications Series,
turn to the back of this book.
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Laser Space Communications
David G. Aviv
artechhouse.com
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A catalog record for this book is available from the U.S.Library of Congress.
A catalogue record for this book is available from the British Library.
ISBN 1-59693-028-4
ISBN 978-1-59693-028-5
Cover design by Robert Pike.
© 2006 by David G. Aviv
Published by ARTECH HOUSE, Inc.
685 Canton Street
Norword, MA 02062
All rights reserved. Printed and bound in the United States of America. No part of this book
may be reproduced or utilized in any form or by any means, electronic or mechanical, includ-
ing photocopying, recording, or by any information storage and retrieval system, without per-
mission in writing from the publisher.
All terms mentioned in this book that are known to be trademarks or service marks have
been appropriately capitalized. Artech House cannot attest to the accuracy of this information.
Use of a term in this book should not be regarded as affecting the validity of any trademark or
service mark.
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The author wishes to express his deepest appreciation to his three sons
and his wife, who inspired the writing of this book and contributed
to its completion.
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Contents
Preface xv
1 Introduction 1
1.1 Overview 1
1.2 Advantages of Lasers over Microwaves 2
1.2.1 Narrow Beamwidth 2
1.2.2 Large Directivity 3
1.2.3 Higher Bandwidth of Lasers Versus Microwaves 4
1.2.4 Privacy Comparison Between Laser
and Microwave 4
1.3 Combined Laser and Microwave Communication 5
1.4 Combined Signal-to-Noise for Microwaves in
Uplink/Downlinks and Laser Crosslinks 7
1.5 Review of the Chapters 8
1.5.1 The Essence of Chapter 2 8
1.5.2 The Essence of Chapter 3 9
1.5.3 Overview of Chapters 4, 5, and 6 10
1.5.4 The Essence of Chapter 7 12
1.5.5 The Essence of Chapter 8 13
1.5.6 The Essence of Chapter 9 14
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2 The Signal Power Budget for Intersatellite Links
and Potential Mars-to-Earth Links 15
2.1 Introduction 15
2.2 Signal Power Budget Calculation 16
2.2.1 Numerical Example 18
2.3 Summary of the Power Budget Expression 20
2.4 Evaluation of BER as a Function of
Photoelectrons per Bit and Modulation Scheme 21
2.4.1 Error Analysis for PGBM 22
2.4.2 Example of Noise Background Calculations 24
2.4.3 Detailed Background Calculations 24
2.5 Direct Detection Versus Heterodyne Detection 25
2.5.1 Signal-to-Noise Ratio for the Direct
Detection Receiver 26
2.5.2 Signal-to-Noise Ratio of the Heterodyne
(Coherent) Receiver 28
2.5.3 Other Modulation Formats 29
2.5.4 Laser Communication Between Mars and
Earth Using PPM Modulation 34
2.6 Expression of Signal Power Budget Due
to Vibrations 35
2.6.1 The Pointing Loss Factors 36
2.6.2 Mathematical Expressions for the
Pointing Losses 36
2.6.3 Satellite Vibrations and Their Effect on the
Communication Link Performance for a
Typical Laser Transceiver Design for ISL 37
2.6.4 Effect of Vibration on the Communication
Links Through a Constellation of Satellites 38
2.7 Azimuthal and Elevation Components of the
Pointing Error Angle in a Constellation
of Satellites 39
2.8 Summary and Concluding Remarks 42
References 42
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3 Acquisition Tracking and Pointing 45
3.1 Introduction 45
3.2 Implementation of the ATP Functions 47
3.2.1 Functional Description 48
3.3 Basic Block Diagram of the ATO on LEO
and GEO 51
3.4 Specific Acquisition Procedures in Step 1 54
3.5 Step 2 of the Acquisition Process 61
3.6 Step 3 of the ATP Process 61
3.6.1 Use of the GPS to Determine the Location
of the LEO 62
3.6.2 Acquisition Timing 63
3.6.3 Acquisition Timing Using GPS 63
3.7 Additional Tracking Considerations 64
3.8 Integration of the ATP Within the
Laser Transceiver 66
3.8.1 The Laser Transceiver for the LEO Satellite 66
3.8.2 Baseline Laser Transceiver with Inertial Sensors 68
3.9 Summary and Concluding Remarks 71
References 72
4 Satellite Downlink Through the Atmosphere 73
4.1 Introduction 73
4.2 Downlink from Satellite to Ground Station 75
4.3 Analytic Expressions of the Downlink Signal 77
4.4 Variation of Angle of Arrival of the
Downlink Signal 82
4.5 Summary and Concluding Remarks 83
References 84
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5 Uplink Laser Communication Through
the Atmosphere 87
5.1 Introduction 87
5.2 Differences Between Downlink and Uplink 88
5.3 Calculating Signal Coupling Efficiency 89
5.4 Coherence Length and Associated
Atmospheric Turbulence 92
5.5 Measurement of Atmospheric Effects
on Downlink and Uplink 93
5.6 Methods of Obtaining a “Reference”
Downlink Signal for Adaptive
Optics Subsystem 95
5.6.1 Synthetic Sodium Laser Beacon 96
5.7 Using a Reference Laser and an Oriented
Mirror 97
5.8 Uplink Signal Loss When AOS Is Not Used 98
5.9 Summary and Concluding Remarks 101
References 101
6 Terrestrial Laser Communication Links and
Weather Issues 103
6.1 Introduction 103
6.2 Calculations of Atmospheric
Turbulence Parameters 104
6.3 Absorption and Scattering in the Atmosphere 105
6.4 Attenuation Due to a Variety of
Weather Components 111
6.4.1 MODTRAN System for Estimating Laser
Signal Penetration of the Atmosphere 112
6.5 The Weather Avoidance System 113