Modern HF Signal Detection and Direction Finding

366 Pages·2018·13.972 MB·English

by  Jay R. Sklar

Modern HF Signal Detection
and Direction Finding
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MIT Lincoln Laboratory Series
Perspectives on Defense Systems Analysis: Ihe What, the Wh~ and the Who, but Mostly
the How ofB road Systems Defense Analysis William P. Delaney
Ultrawideband Phased Array Antenna Technology: For Airborne and Ground-Based
Systems Alan J. Fenn and Peter T. Hurst
Decision Making under Uncertainty: Iheory and Application Mykel J. Kochenderfer
Applied State Estimation and Correlation Chaw-Bing Chang and Keh-Ping Dunn
Perspectives on Space Surveillance Ramaswamy Sridharan and Antonio Pensa, eds.
Mathematics ofB ig Data: Spreadsheets, Databases, Matrices, and Graphs Jeremy Kepner
and Hayden Jansen
Modern HF Signal Detection and Direction Finding Jay R. Sklar
MIT Lincoln Laboratory is a federally funded research and development center that
applies advanced technology to problems of national security. The books in the MIT
Lincoln Laboratory Series cover a broad range of technology areas in which Lincoln
Laboratory has made leading contributions. The books listed above and future volumes
in this series renew the knowledge-sharing tradition established by the MIT Radiation
Laboratory Series published between 1947 and 1953.
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Modern HF Signal Detection
and Direction Finding
Jay R. Sklar
The MIT Press
Cambridge, Massachusetts
London, England
©
2018 Massachusetts Institute of Technology
All rights reserved. No part of this book may be reproduced in any form by any electronic or
mechanical means (including photocopying, recording, or information storage and retrieval)
without permission in writing from the publisher.
This book was set in Adobe Garamond Pro by Westchester Publishing Services. Printed and
bound in the United States of America.
Library of Congress Cataloging-in-Publication Data
Names: Sklar, Jay R., author.
Tide: Modern HF signal detection and direction-finding/ Jay R. Sklar.
Other tides: Modern high frequency signal detection and direction-finding
Description: Cambridge, MA: The MIT Press, [2018] I Series: MIT Lincoln Laboratory
series I Includes bibliographical references and index.
Identifiers: LCCN 2017057048 I ISBN 9780262038294 (hardcover: alk. paper)
Subjects: LCSH: Shortwave radio--Receivers and reception. I Shortwave radio--Antennas. I
Signal detection. I Radio--Interference--Prevention. I Radio direction finders.
Classification: LCC TK6564.S5 S586 2018 I DDC 621.3841/91--dc23
LC record available at https://lccn.loc.gov/2017057048
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Contents
List of Figures ix
List of Tables xv -
Preface xvii
About the Author xix
1 Introduction 1
1 .1 Overview 1
1.2 High-Frequency Propagation 4
1.3 HF Band Utilization 6
1.4 Motivations for Adaptive Antenna Array Application at HF 6
1 .5 Overall Plan of the Book 7
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· 2 HF Propagation Physics and Its Effect on Signals 11
2.1 Ionospheric Medium 11
2.2 Wave Propagation in the Ionosphere 18
2.3 HF Noise Environment 46
2.4 Diurnal Variations 48
3 Common HF Modulation Protocols 51
3.1 Introduction 51
3.2 Analog Signal Moqulation Alternatives 54
3.3 Digital Modulation Approaches 61
3.4 Binary Phase-Shift Keying 66
3.5 HF Modem Design 75
3~6------Government Standards 77
3.7 Summary 84
3.8 Appendix: Morse Code 84
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vi Contents
4 HF ReceiverArchitectural Approaches 89
4.1 Overview · 89
4.2 Architecture·O ptions 90
4.3 Image Control 100
4.4 Analog-to~Digital Converters: Issues and
Performance 104
5 HF Array-Processing Architecture 117
5.1 Detection 117
5.2 Direction Finding 120
5.3 Copy 122
5.4 Reconstruction 124
5.5 Signal Sorting 125
5.6 Geo location 127
6 Vector Models for Adaptive Array Signals 131
6.1 Overview 131
6.2 Array Signal Model 132
6.3 Ideal Propagation Model 134
6.4 A Simple Example 137
6.5 Beam Formation 141
6.6 Weight Vector Computation 142
6.7 Polarization-Sensitive Arrays 144
7 Signal Detection Processing 151
7.1 Overview 151
7.2 HF Environmental Detection Issues 153
7.3 Likelihood Ratio Detection 155
7.4 Perturbation Discovery 159
7.5 Temporally Oriented Detection 176
7.6 Spectrally Oriented Detection 178
7.7 High-Order Statistics 180
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\ Contents vii
8 Array Evaluation: Direction Finding Performance Bounds 185
8.1 Overview 185
8.2 Value of Bounds 186
8.3 Cramer-Rao Bound 192
8.4 Minimum Mean Square Error Bound 198
8.5 Weiss-Weinstein Bound 199
8.6 HF Array Geometry 201
8.7 Some Common HF Antenna Examples 211 -
9 Direction Finding Techniques for HF Applications 217
9.1 Overview 217
9.2 Interferometry: Phase Fitting 217
9.3 Maximum Likelihood Approach to LOB Estimation 220
9.4 The Vector Space Approach-The MUSIC
Algorithm 225
9.5 Direction Finding with Polarization-Sensitive
Arrays 231
9.6 Feature-Based Methods 238
9.7 Eigenvector Rotation 244
10 Geolocation Techniques 249
10.1 Overview 249
10.2 Multisensor Angle-Only Geolocation 250
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10.3 Single-Site Geolocation 256
10.4 Mode Differential Geolocation 259
10.5 Multisite Differential Time-of-Arrival Geolocation 265
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11 Copy: Steering Vector Methods 269
11 .1 Overview 269
11 .2 MSE Beamformer 270
i Steering Vector-Based Copy 271
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11.-4--- ·· MUSIC-Based Copy 273
11.5 Polarization-Based Methods 277
viii Contents
11.6 Copy Weight Tracking 279
11. 7 Wideband Processing 282
12 Copy: Feature Exploitation Methods 289
12.1 Overview 289
12.2 Carrier-Based Nulling 290
12.3 Rate Line-Based Approaches 297
12.4 Constant Modulus Processing 306
12.5 Spectral Difference Processing 309
12.6 On-Off Keyed Signals 319
12. 7 Radar Signals 324
12.8 Voice-Modulated Signals 330
Index 341
List of Figures
1.1 Spectrogram (waterfall plot) example 2
1.2 Atmospheric ion density vs. altitude 5
2.1 Standard atmospheric density vs. altitude compared
to exponential fit 12
2.2 Interaction of the solar wind with Earth and its atmosphere [1] 13
2.3 Variation of radiation flux with zenith angle 14
2.4 Election density vs. altitude: various times of day and
sunspot number [1] 15
2.5 Polarization-dependent refraction 21
2.6 Snell's law refraction geometry 23
2.7 Transmitter-receiver geometry for ionospheric
communication -- 27
2.8 Typical ray paths and their interactions with the ionosphere 28
2.9 Ray path variation with time of day and frequency; ,
(a) 6 MHz, (b) 9 MHz 31
2.10 Geometry of Breit and Tuve's law 33
2.11 Electric field-Vectors and Earth magnetic field for
0- and X-modes 36
2.12 Normalized geometry for ionospheric communication
computations 39
2.13 Transmission curves for 500 km range 40
2.14 Transmission curves for 1000 km range 41
2.15 Transmission curves for 1500 km range 41
2.16 Transmission curves overlaid with ionogram trace 42
2.17 . Canonical multipath geometry 43
2.18 VOACAP example showing CHU signal level at Lexington,
Massachusetts 45
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