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PRINCIPLES OF INTEGRATED MARITIME SURVEILLANCE SYSTEMS
PRINCIPLES OF INTEGRATED MARITIME SURVEILLANCE
SYSTEMS
THE KLUWER INTERNATIONAL SERIES IN ENGINEERING AND COMPUTER SCIENCE
PRINCIPLES OF INTEGRATED MARITIME SURVEILLANCE
SYSTEMS
by
A. Nejat Ince Centre for Defence Studies
Istanbul Technical University Foundation, Istanbul, Turkey
Ercan Topuz Istanbul Technical University, Istanbul, Turkey
Erdal PanaYlrcl I $lK University, Istanbul, Turkey
Cevdet I~lk Istanbul Technical University, Istanbul, Turkey
SPRINGER SCIENCE+BUSINESS MEDIA, LLC
ISBN 978-1-4613-7404-6 ISBN 978-1-4615-5271-0 (eBook) DOI 10.1007/978-1-4615-5271-0
Library of Congress Cataloging-in-Publication Data
A C.I.P. Catalogue record for this book is available from the Library of Congress.
© 1998 by Springer Science+Business Media New York Originally published by Kluwer Academic Publishers in 1998 Softcover reprint of the hardcover 1 st edition 1998
All rights reserved. No part ofthis publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, mechanical, photocopying, recording, or otherwise, without the prior written permission ofthe publisher, Springer Science+Business Media, LLC.
Printed on acid-free paper.
TABLE OF CONTENTS
PREFACE xi
ACKNOWLEDGMENTS xvii
CHAPTER 1 INTRODUCTION 1.1 Objective and Scope 1 1.2 Generic Requirements 2
1.2.1 Basic Requirements 3 1.2.2 Surveillance System 3
1.3 Content of the Book 4 1.4 References 6
CHAPTER 2 MARITIME SURVEILLANCE APPLICATIONS 2.1 Vessel Traffic Services (VTS) 7 2.2 Naval Surveillance Systems 11 2.3 Comparison of Civilian and Military (Naval) Systems 15 2.4 Design Methodology 22 2.5 References 27
ANNEX 2A : Simulation of Naval Surveillance Aircraft Coverage Area and Revisit Time 28
CHAPTER 3 MARITIME ENVIRONMENT 3.1 Effects of the Environment 35 3.2 Sea Conditions 36
3.2.1 Sea Waves 37 3.2.2 Ship Rotations 41 3.2.3 Multipath 42 3.2.4 Ducting Phenomenon 43 3.2.5 Sea Currents 44
3.3 Clutter 45 3.3.1 Clutter Characterisation 45 3.3.2 Surface and Volume Clutter 51
3.4 Sea Clutter 53 3.5 Land Clutter 55 3.6 Atmospheric Clutter 56 3.7 Signal Attenuation by the Propagation Medium 58
3.7.1 Clear Air Attenuation 58 3.7.2 Precipitation Attenuation 58
3.8 References 60
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CHAPTER 4 SENSORS 4.1 Introduction 63 4.2 Radars 64
4.2.1 General Features 64 4.2.2 Radar Equation 74
4.3 Microwave Radar for VTMIS Applications 78 4.3.1 Requirements 79 4.3.2 Typical Specifications FMCW Radars 88
4.4 Microwave Imaging Radars 89 4.4.1 The Role of Microwave Imaging Radars in MSS 90 4.4.2 Range Profiling Radars 91 4.4.3 Basic Principles of Side-Looking SAR 92 4.4.4 Basic Principles ofISAR 98 4.4.5 System Aspects 102 4.4.6 Typical Parameters of Airborne SAR/ISAR 103
4.5 Spaceborne Radars 103 4.5.1 Characteristics 103 4.5.2 Active and Passive Sensing 106 4.5.3 System Requirements 106 4.5.4 Synthetic Aperture Radar Design 109 4.5.5 Need for R&D 113
4.6 Electronic Warfare Support Measures (ESM) 115 4.6.1 The Role of ESM and ELINT in Maritime
Surveillance 115 4.6.2 ESM Requirements 117 4.6.3 ESM Subsystems 117 4.6.4 ESM Receiver Types 120 4.6.5 Direction Finding Techniques 121 4.6.6 Maximum Intercept Range of ESM Receivers 123
4.7 Optical and IR Sensors 125 4.7.1 Optical and IR Sensors in Maritime Surveillance 125 4.7.2 Basic Quantities and Terminology 126 4.7.3 Atmospheric Transmission and Visibility 128 4.7.4 Radiation From Targets and the Environment 131 4.7.5 Parameters of the System Optics 133 4.7.6 Performance Parameters 137 4.7.7 Typical Sensor Specifications 140
4.8 Global Positioning System (GPS) 142 4.8.1 GPS for Maritime Surveillance 142 4.8.2 Differential GPS (dGPS) 150 4.8.3 Transmission of Differential Corrections 156 4.8.4 Combined LORAN-C/dGPS (EUROFIX) 163 4.8.5 Future Trends in Satellite Navigation 163
4.9 HF Over-the-Horizon Radar 166 4.9.1 The Role of HF Radar in MSS 166 4.9.2 Skywave Propagation 167 4.9.3 Surface Wave Path Loss Calculations 168
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4.9.4 RCS Considerations 170 4.9.5 Antenna Performance 171 4.9.6 HF Spectrum Occupancy 171 4.9.7 Sea Clutter at HF Frequencies 172 4.9.8 Monitoring the Sea Surface With HF Radar 173 4.9.9 Typical Parameters of HF Radars 175
4.10 References 176 ANNEX 4A: Orbital Parameters for
Surveillance Satellites 179 ANNEX 4B: Synthetic Aperture Radar System
Definition and Design Procedures 184
CHAPTERS SENSOR PLATFORMS 5.1 Types of Platforms 187 5.2 Maritime Surveillance Aircraft (MSA) 188
5.2.1 Mission 188 5.2.2 TypesofMSA 189 5.2.3 Quantity of Aircraft 193 5.2.4 Mission and Flight Profiles 195 5.2.5 Integration 196
5.3 Helicopters 198 5.4 Unmanned Air Vehicles (UAV) 199
5.4.1 Missions 199 5.4.2 Classification of U A V 200
5.5 Aerostats 204 5.6 Airborne Platforms for SAR 206
5.6.1 Search and Rescue 206 5.6.2 Communications 208 5.6.3 Vessel Features for SAR 209 5.6.4 Search Patterns 210
5.7 References 213
CHAPTER 6 PRINCIPLES OF AUTOMATIC TARGET RECOGNITION IN A MARITIME ENVIRONMENT 6.1 Scope 215 6.2 EM Characterization of Vessels 216 6.3 Principles of Target Classification by Radar 221
6.3.1 Feature Extraction 222 6.3.2 Classification 224
6.4 Classification of Targets by Radar 228 6.4.1 Levels of Classification 228 6.4.2 Automatic Classification by Radar 229
6.5 Classification and Identification by ESM 232 6.6 IFF Classification 234 6.7 Low Observable Technology 235
6.7.1 Methods ofRCS Reduction 236
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6.7.2 Detection and Classification of Stealthy Targets 238 6.8 References 238
CHAPTER 7 MULTISENSOR DATA FUSION 7.1 Objective 241 7.2 Types of Data Fusion 245
7.2.1 Centralized Data Fusion 245 7.2.2 Distributed Data Fusion 246
7.3 Levels of Data Fusion 248 7.4 Sensor Attributes 251 7.5 Algorithms for Multisensor Data Fusion 253
7.5.1 Positional Fusion Algorithms 254 7.5.2 Identity Fusion Algorithms 255 7.5.3 Ancillary Support Algorithms 258
7.6 Positional Fusion Algorithms 259 7.6.1 Multi Target Tracking 259 7.6.2 Common Time and Coordinate Reference 266 7.6.3 Positional Fusion Algorithms 267
7.7 Decision-Level Identity Fusion 270 7.7.1 Classical Inference 271 7.7.2 Bayes Method 274 7.7.3 The Demster-Shafer Method for Identity Fusion 276 7.7.4 A Simulation Model for Bayes and
Demster-Shafer Fusion Algorithms 283 7.8 Feature-Level Identity Fusion 286
7.8.1 Cluster Analysis Methods 287 7.8.2 Adaptive Neural Nets 289 7.8.3 Voting Methods 290 7.8.4 Parametric Templates 290
7.9 Display System 291 7.10 Database Management 297 7.11 References 301
CHAPTER 8 COMMUNICATIONS SYSTEMS AND DATA LINKS 8.1 General 305 8.2 Communications for VTMIS 305
8.2.1 Requirements 305 8.2.2 RSS-VTC Communications 306 8.2.3 Ship-to-VTC Communications 307 8.2.4 Intra VTC Communications 313 8.2.5 Inter VTC Communications 314 8.2.6 Communications Between VTC and Relevant
Authorities 314 8.2.7 Crisis Management Communications 314 8.2.8 VTC-Ship Owners/Agents Communications 316 8.2.9 Public Communications 316 8.2.10 Type of Communications 316
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8.3 Naval Surveillance System Communications 316 8.3.1 System Composition 316 8.3.2 Communication Requirements 317 8.3.3 Possible Data Link Solutions 323
8.4 Error Analysis of the Positional data 339 8.5 References 348
CHAPTER 9 SIMULATION OF MARITIME SURVEILLANCE SYSTEMS 9.1 Introduction 349 9.2 The Characteristics of Simulation 352
9.2.1 Need for Simulation 352 9.2.2 Accelerated Simulation Methods 355 9.2.3 Verification and Validation 356 9.2.4 Event Based Simulation 357
9.3 Simulation of MSS 360 9.3.1 General Aspects 360 9.3.2 Sensor Models 361
9.4 Simulation In Maritime Surveillance (SIMS) 365 9.4.1 Description of the Model 365 9.4.2 Event Routines 370 9.4.3 Sample Outputs 397
9.5 An Off-Line Simulator for Construction of a Scattering Centre Representation of Ships (GRS) 399
9.5.1 Introduction 399 9.5.2 Model Outline 400 9.5.3 Sample Outputs 402
9.6 A Traffic Flow Simulator: TURBO 404 9.6.1 Requirements for a Traffic Flow Simulator 404 9.6.2 Model Outline 405
9.7 References 415
CHAPTER 10 NEW TECHNOLOGIES, NEW FUNCTIONS AND SOLUTIONS 10.1 Areas of R&D for VTMIS 417 10.2 Silent VTS 417 10.3 Developments in Sensor and Data Processing
Technologies 418 10.4 Developments in Communications 418 10.5 Developments in dGPS 419 10.6 New Functions and Solutions 420
10.6.1 Automatic Ships Tracking 420 10.6.2 Automatic Ships Identification (AIS) 422 10.6.3 Electronic Chart Display and Information
System (ECDIS) 426 10.6.4 Additional Ships Motion Data 427
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10.6.5 Visualisation of Collision-Avoidance Information and Decision Support for Encounter Situations 428
10.6.6 Extended Path Prediction Function 429 10.6.7 VTS Information Recording and Play-back 431 10.6.8 Remote Pilotage 431 10.6.9 Non-Cooperative Tracking of High Speed
and Low RCS Vessels 432 10.6.10 Intelligent Knowledge-Based Systems (UrnS) 433
10.7 Issues to be Resolved for Safe and Efficient Navigation with VTS 433 10.7.1 The Issues 433 10.7.2 Comment on the Issues 434
10.8 References 461 ANNEX lOA Electronic Chart Display And
Information Systems (ECDIS) 463 ANNEX lOB ECDIS for VTS 467
CHAPTER 11 COST ANALYSIS AND IMPLEMENTATION PLANNING 11.1 Cost Methodology 469 11.2 Investment Costs 470 11.3 Operational and Maintenance Costs 472 11.4 Total Cost 474 11.5 Reliability and Availability 474 11.6 Implementation Planning 479
11.6.1 Implementation Strategy 479 11.6.2 Principles of Implementation 481
11.7 References 483
INDEX 485
PREFACE
Three quarters of the globe's surface is covered with water on which depends a significant portion of the world trade and transportation with vessels of various types some of which are platforms for weapons. The activities in which these vessels are involved vary from pleasure cruising to transportation of conventional goods as well as hazardous chemicals and even nuclear materials. Safe and efficient navigation of these vessels can reduce to a minimum the risk of marine accidents (collisions, grounding, ramming) and the resulting casualties and economic losses as well as environmental polution due to spills of hazardous cargo. Provision of a well designed maritime surveillance and control system capable of tracking ships and providing navigational and other types of information required for safe navigation and efficient commercial operation is therefore essential and would be of vital interest to a variety of user groups ranging from port authorities to shipping companies and marine exchanges as well as to civil goverments and the military. This book adresses the problems related to the design of such a Vessel Traffic Management and Information System (VTMIS) which shall be called here Integrated Maritime Surveillance System (MSS) or simply MSS. The problems specific to naval MSS are also identified and treated in fair detail in the book.
The planning and architectural design of the MSS will be the main objective of the book driven by the user requirements. These will cover a variety of service demands including determination of position, course, velocity, classification and identification of objects on or near the sea surface as well as evaluation and dissemination to the users of this data for safe navigation. The book will also deal with systems aspects such as ship-shore communications, reliability, flexibility, interoperability with other systems and of course, cost.
It should be reiterated here that the function of the MSS would be monitoring and continuous observation of surface traffic in coastal waters and open seas as well as through waterways, straits, lakes and harbours. In addition to the traffic management the MSS would also serve missions such as military (naval) surveillance, search and rescue (SAR) operations, Extended Economic Zone (EEZ) Control, customs and environmental controls.
Surveillance, as an integral part of intelligence, is the most important ''Force Multiplier" for maritime traffic supervision and control. The ultimate objective of the MSS is to form a recognized surface picture of the maritime traffic which involves vessels of different types scattered over the surveillance area, part of which
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may not be continuously observable due to geographical constraints and intermittent observation of the area.
Different types of sensors and sensor combinations are considered. These include active sensors such as imaging microwave radars with range profiling and ISARISAR modes of operation, ARPA (Automatic Radar Plotting Aid), HF surface wave and sky wave radars and passive devices such as GPS transponders, Electronics Support Measures (ESM), optical and IR sensors. These sensors may be operated from land-based, shipborne, and airborne platforms as well as from satellites. The book discusses all these in the context of overall system requirements.
The coverage provided by each of the sensor stations within the predefined operational area depends upon locations of sensors, sensor parameters, geography of the operational area and the environmental conditions such as precipitation and sea state in the area which may affect detection and classification performance of the sensors. Depending on the system configuration the operational area may be divided into subareas as completely uncovered, surveilled only by one sensor and areas surveyed by more than one sensor.
As a result of the movement of the ship itself or the sensor platform the number of simultaneous observations of the target will change with time hence the need for data fusion for optimal surveillance performance.
The construction, continuation and maintenance of the so-called "Recognized Surface Picture (RSP)" for the area of interest require in addition to detection, classification and identification of the objects as well. The book adresses these subjects with emphasis on Automatic Target Recognition (ATR) including such issues as segmentation, feature extraction and classification algorithms.
The main subsystems of the MSS will be:
1) Active sensors and platforms 2) Passive sensors and platforms 3) Communication links 4) Fusion post 5) Information dissemination
All-weather, and day and night surveillance of an area for the purposes of tracking, classification and identification will require a mixture of active sensors such as microwave and HF radars. The microwave radars must have the features of range profiling, SAR and ISAR to be able to detect as well as to classify. Ground based microwave radars will in general be used for coastal surveillance. Elevated platforms such as baloons, helicopters, aircraft, and satellites may be used for surveillance of large areas. Elevated single platforms often provide intermittent surveillance and in these cases continuity of observersation at intermediate ranges may be assured by the use of an HF radar, albeit with a spatial resolution less than that obtainable with a microwave radar.
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The radars give positional and classification information with the required degree of accuracy but can not provide positive identification of non-cooperating targets which require visual sighting or, when targets emit EM signals, the use of passive sensing via microwave, optical and I or IR sensors.
The positional and identification information of cooperating vessels may be obtained by IFF or by radio navigation systems including a Global Positional System the best known of which are NAVSTAR of the United States of America and GLONASS of the Russian Federation.
The communications subsystem of the MSS provides links carrying suitably formatted target information obtained by the sensors to a central fusion post where this data, together with other data, such as humint will be fused to obtain the best estimate of the Recognized Surface Picture (RSP). In the opposite direction RSP, and when required, Electronic Nautical Chart (ENC) can be sent to various interested parties as input to the Electronic Chart Display and Information System (ECDIS).
The information contained in RSP coupled with geographic and environmental factors may be used through an expert system to derive future courses of events which will aid decision making on shore and at sea of various kinds involving at one extreme safety of navigation and Search and Rescue and at the other extreme a plan of attack on an adversary.
The book describes in appropriate details the characteristics and features of the sensors which may be used in a surveillance system and the communications links and message format which can be employed to convey the types of information required on land and sea.
The heart of the MSS is the fusion post where the traffic control functions reside. The book gives different approaches and algorithms for multisensor data fusion. In particular, types and levels of data fusion, sensor attributes, decision making and data base management aspects are identified and discussed in detail.
The test of concept, design and expected performance of complex systems such as the MSS is often validated and verified through the use of an event-driven system simulator. In the book we give a detailed description of a simulator called "Simulation In Maritime Surveillance (SIMS)" which was developed under the direction of the authors and used for the design validation of two surveillance systems that are to be implemented. Because it embodies all the important features of a real MSS, SIMS is given relatively more space here than provided for other subjects to make the reader aware right at the beginning, that most of the design information provided in the book has been verified and validated by simulations and some by actual experiments.
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SIMS is a simulation model of maritime surveillance by an integrated network of sensors which supply, via data links, information to the fusion post. Each sensor installation on land, sea and in the air comprises radar equipment, with target classification/identification capability by means of range profiling and ISAR and ESM equipment.
The function of the surveillance radar is to detect (confirm), maintain, and delete tracks and generate classification probability vectors on surface targets within a defined area of coverage. The probability statement is derived from measurements of ReS variation across a vessel, these being converted into probability by comparison with pre-stored reference profiles of known ship classes.
The function of the ESM is to provide a statement of probability of ship class for detected surface tracks. This probability statement is an input to the fusion system. The probability statement is derived from the presence of emitters along the bearing of the detected track, these being converted into probability of ship class based on apriori knowledge of the distribution of emitters across the ship classes.
The function of the fusion post is to combine the reports from the linked sensor installations into a fused picture showing detected, classified ships over the entire sea area. The fusion post model does not attempt to provide an optimum solution for the MSS, but rather a starting point from which the user can build towards a solution that meets the performance specification for the real system.
For the airborne sensor in the model, the aircraft Internal Navigation System (INS) assumes a random drift component caused by velocity estimate bias. The INS is updated at user defined intervals by an accurate position and velocity fix obtained from satellite navigation (i. e. GPS).
The model takes as input the complete set of ship targets, plus a description of current platform position and trajectory, and the environmental conditions of sea state and rain across the modelled area. It is possible to define different environmental conditions in different subregions of the operational area.
The model determines the visibility of targets as a function of radar sector blanking, horizon range, terrain obstruction and radar resolution capabilities. In the case of radar resolution, the model reflects in fact that radar encounters problems when targets are in close proximity (e. g. convoys). This can lead to problems in both tracking and classification, and the model therefore assumes that such conditions can be detected in the radar plot extractor, and that plots are deleted when interference occurs.
The model permanently maintains a track record for each ship. Local tracks are reported to the fusion post upon confirmation and at user defined intervals thereafter. Random errors, with user defined r.m.s. values, are added to the true position and velocity of the target when generating system track messages. The fusion post is also informed when a local track is deleted.
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The model simulates not only target detection events but also a complete radar classification event. The model takes as input the identity of the ship being classified, plus RCS description of all classes of ships.
The RSC description of a ship is defined, via the user interface, as an array of scatterers, where each scatterer is defined by 3D position, magnitude, and arc of view. These scatterers are not point scatterer but rather are summaries of volume scatterers that give rise to peaks in the RCS profile of the ship. For the ship being classified, this array of scatterers is converted to a measured range profile by computing for each (visible) scatterer the range cell into which it falls then adding its RCS to the total RCS for that range cell. Random signals are applied to represent the effects of glint, clutter, and receiver noise.
In the ISAR case, a Doppler frequency is computed for each (visible) scatterer as a function of randomly generated yaw, pitch, and roll rates, and ship viewing angle. The average rotation rates vary with sea state and target class. Within a range cell, scatterers are allocated to Doppler cells with the Doppler resolution being the inverse of the coherent processing interval. The RCS of the scatterer is added to the total for the range-Doppler cell into which it falls.
The output of the simulator for a given scenario which can accommodate several hundreds of ships of different types include all data related to all events during a simulation run leading up to the RSP which has the realism of a real MSS.
In a fast developing area of VTS and naval surveillance it may be expected that there would be intense research and development efforts directed at producing better sensors, more effective datalknowledge processing technologies, improvements in communications and navigation services. The book discusses all these new technologies, functions and solutions which are expected to enhance vessel traffic services and the performance of maritime surveillance systems world wide.
The book concludes with a chapter on costing methodology and implementation planning including the treatment of subjects such as evolutionary system acquisition, implementation phasing and system availability as factors to be used for cost reduction which may be necessitated by financial and other constraints.
ACKNOWLEDGMENTS
Most of the material used in this book has been derived from the studies concerning two maritime surveillance systems which have been carried out under the direction of Prof Ince during the past ten years.
These studies were inspired and instigated by Admiral (R) GUven Erkaya, the ExCommander of the Turkish Naval Forces. We owe him a great deal of gratitude since without his vision and encouragement this book would not have been written.
We wish to express our gratitude to the many scentists and engineers of the Centre for Defence Studies of Istanbul Technical University Foundation who worked on the two projects mentioned above and contributed indirectly to the book. We would particularly like to mention here Prof Dr Murat Tayh, Dr Ali S. $anal, Dr Merdan Metin and Captain Habib KUl;iikoglu who made important contributions to our studies. We wish to thank also Mr Z. Ener, Mrs G. C. Ince and the staff of Kluwer Academic Publishers for the help given in the production of this book.
Last but by no means least we would like to express our appreciation for the many stimulating and inspiring discussions we have had with Dr Ulrich Klinge, Director General Maritime Aids to Navigation of the Ministry of Transport of the Federal Republic of Germany and President of IALA. We owe special thanks to Mr Gerard Thiele of Dassault Aviation from whom we have learned so much about naval surveillance.
