PRINCIPLES OF INTEGRATED MARITIME SURVEILLANCE SYSTEMS

Transcription

1 PRINCIPLES OF INTEGRATED MARITIME SURVEILLANCE SYSTEMS

2 THE KLUWER INTERNATIONAL SERIES IN ENGINEERING AND COMPUTER SCIENCE

3 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

4 ISBN ISBN (ebook) DOI / Library of Congress Cataloging-in-Publication Data A C.I.P. Catalogue record for this book is available from the Library of Congress 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.

5 TABLE OF CONTENTS PREFACE ACKNOWLEDGMENTS xi xvii CHAPTER 1 CHAPTER 2 CHAPTER 3 INTRODUCTION 1.1 Objective and Scope Generic Requirements Basic Requirements Surveillance System Content of the Book References 6 MARITIME SURVEILLANCE APPLICATIONS 2.1 Vessel Traffic Services (VTS) Naval Surveillance Systems Comparison of Civilian and Military (Naval) Systems Design Methodology References 27 ANNEX 2A : Simulation of Naval Surveillance Aircraft Coverage Area and Revisit Time 28 MARITIME ENVIRONMENT 3.1 Effects of the Environment Sea Conditions Sea Waves Ship Rotations Multipath Ducting Phenomenon Sea Currents Clutter Clutter Characterisation Surface and Volume Clutter Sea Clutter Land Clutter Atmospheric Clutter Signal Attenuation by the Propagation Medium Clear Air Attenuation Precipitation Attenuation References 60

6 vi CHAPTER 4 SENSORS 4.1 Introduction Radars General Features Radar Equation Microwave Radar for VTMIS Applications Requirements Typical Specifications FMCW Radars Microwave Imaging Radars The Role of Microwave Imaging Radars in MSS Range Profiling Radars Basic Principles of Side-Looking SAR Basic Principles ofisar System Aspects Typical Parameters of Airborne SAR/ISAR Spaceborne Radars Characteristics Active and Passive Sensing System Requirements Synthetic Aperture Radar Design Need for R&D Electronic Warfare Support Measures (ESM) The Role of ESM and ELINT in Maritime Surveillance ESM Requirements ESM Subsystems ESM Receiver Types Direction Finding Techniques Maximum Intercept Range of ESM Receivers Optical and IR Sensors Optical and IR Sensors in Maritime Surveillance Basic Quantities and Terminology Atmospheric Transmission and Visibility Radiation From Targets and the Environment Parameters of the System Optics Performance Parameters Typical Sensor Specifications Global Positioning System (GPS) GPS for Maritime Surveillance Differential GPS (dgps) Transmission of Differential Corrections Combined LORAN-C/dGPS (EUROFIX) Future Trends in Satellite Navigation HF Over-the-Horizon Radar The Role of HF Radar in MSS Skywave Propagation Surface Wave Path Loss Calculations 168

7 4.9.4 RCS Considerations Antenna Performance HF Spectrum Occupancy Sea Clutter at HF Frequencies Monitoring the Sea Surface With HF Radar Typical Parameters of HF Radars References 176 ANNEX 4A: Orbital Parameters for Surveillance Satellites 179 ANNEX 4B: Synthetic Aperture Radar System Definition and Design Procedures 184 vii CHAPTERS CHAPTER 6 SENSOR PLATFORMS 5.1 Types of Platforms Maritime Surveillance Aircraft (MSA) Mission TypesofMSA Quantity of Aircraft Mission and Flight Profiles Integration Helicopters Unmanned Air Vehicles (UAV) Missions Classification of U A V Aerostats Airborne Platforms for SAR Search and Rescue Communications Vessel Features for SAR Search Patterns References 213 PRINCIPLES OF AUTOMATIC TARGET RECOGNITION IN A MARITIME ENVIRONMENT 6.1 Scope EM Characterization of Vessels Principles of Target Classification by Radar Feature Extraction Classification Classification of Targets by Radar Levels of Classification Automatic Classification by Radar Classification and Identification by ESM IFF Classification Low Observable Technology Methods ofrcs Reduction 236

8 viii Detection and Classification of Stealthy Targets References 238 CHAPTER 7 CHAPTER 8 MULTISENSOR DATA FUSION 7.1 Objective Types of Data Fusion Centralized Data Fusion Distributed Data Fusion Levels of Data Fusion Sensor Attributes Algorithms for Multisensor Data Fusion Positional Fusion Algorithms Identity Fusion Algorithms Ancillary Support Algorithms Positional Fusion Algorithms Multi Target Tracking Common Time and Coordinate Reference Positional Fusion Algorithms Decision-Level Identity Fusion Classical Inference Bayes Method The Demster-Shafer Method for Identity Fusion A Simulation Model for Bayes and Demster-Shafer Fusion Algorithms Feature-Level Identity Fusion Cluster Analysis Methods Adaptive Neural Nets Voting Methods Parametric Templates Display System Database Management References 301 COMMUNICATIONS SYSTEMS AND DATA LINKS 8.1 General Communications for VTMIS Requirements RSS-VTC Communications Ship-to-VTC Communications Intra VTC Communications Inter VTC Communications Communications Between VTC and Relevant Authorities Crisis Management Communications VTC-Ship Owners/Agents Communications Public Communications Type of Communications 316

9 8.3 Naval Surveillance System Communications System Composition Communication Requirements Possible Data Link Solutions Error Analysis of the Positional data References 348 ix CHAPTER 9 SIMULATION OF MARITIME SURVEILLANCE SYSTEMS 9.1 Introduction The Characteristics of Simulation Need for Simulation Accelerated Simulation Methods Verification and Validation Event Based Simulation Simulation of MSS General Aspects Sensor Models Simulation In Maritime Surveillance (SIMS) Description of the Model Event Routines Sample Outputs An Off-Line Simulator for Construction of a Scattering Centre Representation of Ships (GRS) Introduction Model Outline Sample Outputs A Traffic Flow Simulator: TURBO Requirements for a Traffic Flow Simulator Model Outline References 415 CHAPTER 10 NEW TECHNOLOGIES, NEW FUNCTIONS AND SOLUTIONS 10.1 Areas of R&D for VTMIS Silent VTS Developments in Sensor and Data Processing Technologies Developments in Communications Developments in dgps New Functions and Solutions Automatic Ships Tracking Automatic Ships Identification (AIS) Electronic Chart Display and Information System (ECDIS) Additional Ships Motion Data 427

10 x Visualisation of Collision-Avoidance Information and Decision Support for Encounter Situations Extended Path Prediction Function VTS Information Recording and Play-back Remote Pilotage Non-Cooperative Tracking of High Speed and Low RCS Vessels Intelligent Knowledge-Based Systems (UrnS) Issues to be Resolved for Safe and Efficient Navigation with VTS The Issues Comment on the Issues 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 Investment Costs Operational and Maintenance Costs Total Cost Reliability and Availability Implementation Planning Implementation Strategy Principles of Implementation References 483 INDEX 485

11 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

12 xii 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.

13 xiii 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.

14 xiv 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.

15 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. xv

16 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 Ex Commander 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.