Radar and ARPA Manual

PrefaceAcknowledgments1 Basic Radar Principles 1.1 Introduction 1.2 Principles of Range Measurement 1.2.1 The Echo Principle 1.2.2 Range as a Function of Time 1.2.3 The Timebase 1.2.4 Calibration of the Timebase 1.2.5 The Synthetic Display 1.3 Principles of Bearing Measurement 1.3.1 Directional Transmission and Reception 1.3.2 Synchronization of Scanner and Trace 1.3.3 The Build-up of the Picture 1.3.4 The Heading Marker 1.3.5 Bearing Measurement 1.4 Picture Orientation 1.4.1 Ship's-Head-up Orientation (Unstabilized) 1.4.2 True-North-up Orientation (Stabilized) 1.4.3 Course-up Orientation (Stabilized) 1.4.4 Choice of Orientation 1.5 Picture Presentation 1.5.1 The Relative-Motion Presentation 1.5.2 The True-Motion Presentation 1.5.3 Choice of Presentation2 The Radar System - Operational Principles 2.1 Introduction 2.2 Function of Units 2.2.1 The Transmitter Function 2.2.2 The Aerial Function 2.2.3 The Receiver Function 2.2.4 The Display Function 2.3 Transmitter Principles 2.3.1 The Pulse Repetition Frequency 2.3.2 The Pulse Length, Power and Shape 2.3.3 The Radio Frequency of the Transmitted Pulse 2.3.4 Selection of PRF and Pulse Length and Their Relationship with Range Scale 2.4 Aerial Principles 2.4.1 Aerial Concepts 2.4.2 The Horizontal Beamwidth 2.4.3 The Vertical Beamwidth 2.4.4 Aerial Rotation Rate 2.4.5 Aerial and Display Rotation Link 2.4.6 Heading Marker Data 2.5 Receiver Principles 2.5.1 The Radio Frequency Section 2.5.2 The Intermediate Frequency Amplifier 2.5.3 The Video Section 2.6 Display Principles 2.6.1 The Cathode Ray Tube 2.6.2 Real-time Picture Generation 2.6.3 Compass (or Azimuth) Stabilization 2.6.4 The Provision of True-Motion Facilities 2.6.5 Echo Paint 2.6.6 The Radial-Scan Synthetic Display 2.6.7 The Raster-Scan Synthetic Display 2.7 The Siting of Units on Board Ship 2.7.1 Aerial Siting 2.7.2 The Transceiver Unit 2.7.3 The Display Unit 2.7.4 Compass Safe Distances 2.7.5 Exposed and Protected Equipment 2.7.6 Power Supplies 2.7.7 High Voltage Hazards 2.7.8 Interswitching3 Target Detection 3.1 Introduction 3.2 Radar Characteristics 3.2.1 Transmitter Characteristics 3.2.2 Antenna Characteristics 3.2.3 Receiver Characteristics 3.2.4 Minimum Detection Range 3.3 Target Characteristics 3.3.1 Aspect 3.3.2 Surface Texture 3.3.3 Material 3.3.4 Shape 3.3.5 Size 3.3.6 Responses from Specific Targets 3.4 Target Enhancement — Passive 3.4.1 Corner Reflectors 3.4.2 Arrays of Reflectors 3.4.3 The Lunenburg Lens 3.4.4 Buoy Patterns 3.5 Target Enhancement - Active 3.5.1 The Racon Principle 3.5.2 The Racon Appearance on the Display 3.5.3 Frequency and Polarization 3.5.4 The Ramark 3.5.5 Sources of Radar Beacon Information 3.5.6 The Radaflare 3.5.7 Racons for Survival Craft 3.6 The Detection of Tar Gets in Sea Clutter 3.6.1 The Nature of the Sea Clutter Response 3.6.2 The Clutter Problem Summarized 3.6.3 The Suppression of Displayed Sea Clutter Signals 3.7 The Detection of Targets in Precipitation Clutter 3.7.1 The Nature of Precipitation Response 3.7.2 Attenuation in Precipitation 3.7.3 The Effect of Precipitation Type 3.7.4 The Suppression of Rain Clutter 3.7.5 Combating the Attenuation Caused by Precipitation 3.7.6 Exploiting the Ability of Radar to Detect Precipitation 3.8 The Radar Horizon 3.8.1 The Effect of Standard Atmospheric Conditions 3.8.2 Sub-Refraction 3.8.3 Super-Refraction 3.8.4 Extra Super-Refraction or Ducting 3.9 False and Unwanted Radar Responses 3.9.1 Introduction 3.9.2 Indirect Echoes (Reflected Echoes) 3.9.3 Multiple Echoes 3.9.4 Side Echoes 3.9.5 Radar-to-Radar Interference 3.9.6 Second-Trace Echoes 3.9.7 False Echoes from Power Cables4 Automatic Radar Plotting Aids (ARPA), Specified Facilities 4.1 Introduction 4.1.1 Stand-Alone ARPAs 4.1.2 Integral ARPAs 4.1.3 The Requirement to Carry ARPA, and for Operator Training 4.1.4 Compliance with the IMO Performance Standards 4.2 The Acquisition of Targets 4.2.1 The Acquisition Specification 4.2.2 Manual Acquisition 4.2.3 Fully Automatic Acquisition 4.2.4 Automatic Acquisition by Area 4.2.5 Guard Zones 4.2.6 Guard Rings and Area Rejection Boundaries (ARBs) 4.3 The Tracking of Targets 4.3.1 The Tracking Specification 4.3.2 Rate Aiding 4.3.3 The Number of Targets to be Tracked 4.3.4 Target Loss 4.3.5 Target Swop 4.3.6 The Analysis of Tracks and the Display of Data 4.3.7 Tracking History 4.4 Vectors 4.4.1 Relative Vectors 4.4.2 True Vectors 4.4.3 Trial Maneuver 4.5 The ARPA Display 4.5.1 The Continued Availability of Radar Data in the Event of an ARPA Malfunction 4.5.2 The Size of the Display 4.5.3 The Range Scales on Which ARPA Facilities should be Available 4.5.4 The Modes of Display 4.5.5 ARPA Data should not Obscure Radar Data 4.5.6 The ARPA Data Brilliance Control 4.5.7 The Ability to View the Display 4.5.8 The Use of the Marker for Range and Bearing Measurement 4.5.9 The Effect of Changing Range Scales 4.6 The Display of Alphanumeric Data 4.7 Alarms and Warnings 4.7.1 Guard Zone Violation 4.7.2 Predicted CPA/TCPA Violation 4.7.3 Lost Target 4.7.4 Performance Tests and Warnings 4.8 Connections with Other Equipment5 ARPA - Additional Facilities 5.1 Introduction 5.2 Additional Alarms and Warnings 5.2.1 Loss of Sensor Input 5.2.2 Track Change 5.2.3 Anchor Watch 5.2.4 Tracks Full 5.2.5 Wrong or Invalid Request 5.2.6 Time to Maneuver 5.2.7 Safe Limit Vector Suppression 5.2.8 Trial Alarm 5.3 Automatic Ground-Stabilization 5.4 Navigational Lines and Maps 5.5 The Potential Point of Collision (PPC) 5.5.1 The Concept of Collision Points 5.5.2 The Behavior of Collision Points if the Observing Ship Maintains Speed 5.5.3 The Behavior of the Collision Point When the Target Ship's Speed Changes 5.5.4 The Behavior of the Collision Point When the Target Changes Course 5.6 The Predicted Area of Danger (PAD) 5.6.1 The PAD in Practice 5.6.2 Changes in the Shape of the PAD 5.6.3 The Movement of the PAD6 The Radar System - Operational Controls 6.1 Optimum Performance 6.2 Setting-up Procedure for an Analogue Display 6.2.1 Preliminary Procedure 6.2.2 Switching on 6.2.3 Preparing the Display 6.2.4 Obtaining the Optimum Picture 6.3 Setting-up Procedure for a Radial-Scan Synthetic Display 6.3.1 Preliminary Procedure 6.3.2 Switching on 6.3.3 Preparing the Display 6.3.4 Obtaining the Optimum Picture 6.4 Setting-up Procedure for a Raster-Scan Synthetic Display 6.4.1 Preliminary Procedure 6.4.2 Switching on 6.4.3 Preparing the Display 6.4.4 Obtaining the Optimum Picture 6.5 Performance Monitoring 6.5.1 The Principle of the Echo Box 6.5.2 Echo Box Siting 6.5.3 Power Monitors 6.5.4 Transponder Performance Monitors 6.5.5 Calibration Levels 6.5.6 Performance Check Procedure 6.6 Change of Range Scale and/or Pulse Length 6.7 The Stand-by Condition 6.8 Setting up the Display for a True-Motion Picture Presentation 6.8.1 The Controls 6.8.2 Setting up a Sea-Stabilized Presentation 6.8.3 Setting up a Ground-Stabilized Presentation 6.9 Controls for Range and Bearing Measurement 6.9.1 Fixed Range Rings 6.9.2 Variable Range Marker (VRM) 6.9.3 The Perspex Cursor 6.9.4 Parallel Index 6.9.5 The Electronic Bearing Line (EBL) 6.9.6 Free Electronic Range and Bearing Line 6.9.7 Joystick and Screen Marker 6.9.8 Range Accuracy 6.9.9 Bearing Accuracy 6.10 Controls for the Suppression of Unwanted Responses 6.10.1 Sea Clutter Suppression 6.10.2 Rain Clutter Suppression 6.10.3 Interference Suppression 6.11 Miscellaneous Controls 6.11.1 Echo Stretch 6.11.2 Second-Trace Echo Elimination 6.12 Setting-up Procedure for an ARPA Display 6.12.1 The Input of Radar Data 6.12.2 Switching on the Computer 6.12.3 Heading and Speed Input Data 6.12.4 Setting the ARPA Brilliance 6.12.5 Setting the Vector Time Control 6.12.6 Setting the Vector Mode 6.12.7 Safe Limits 6.12.8 Preparation for Tracking 6.13 Switching off7 Radar Plotting 7.1 Introduction 7.2 The Relative Plot 7.2.1 The Vector Triangle 7.2.2 The Plotted Triangle 7.2.3 The Construction of the Plot 7.2.4 The Practicalities of Plotting 7.2.5 The Need to Extract Numerical Data 7.2.6 The Plot in Special Cases Where no Triangle 'Appears' 7.3 The True Plot 7.4 The Plot When only the Target Maneuvers 7.4.1 The Construction of the Plot 7.4.2 The Danger in Attempting to Guess the Action Taken by a Target 7.5 The Plot When Own Ship Maneuvers 7.5.1 The Plot When Own Ship Alters Course only 7.5.2 The Construction of the Plot 7.5.3 The Plot When Own Ship Alters Speed only 7.5.4 The Construction of the Plot 7.5.5 The Use of 'Stopping Distance' Tables, Graphs and Formula 7.5.6 The Plot When Own Ship Combines Course and Speed Alterations 7.5.7 The Plot When Own Ship Resumes Course and/or Speed 7.5.8 The Plot When both Vessels Maneuver Simultaneously 7.6 The Theory and Construction of PPCs, PADs, SODs and SOPs 7.6.1 The Possible Point of Collision (PPC) 7.6.2 The Construction to Find the PPC 7.6.3 The Predicted Area of Danger (PAD) 7.6.4 The Construction of the PAD 7.6.5 The Sector of Danger (SOD) 7.6.6 The Construction of a Sector of Danger 7.6.7 The Sector of Preference (SOP) 7.6.8 The Construction of a Sector of Preference 7.7 The Plot in Tide 7.7.1 The Construction of the Plot 7.7.2 The Course to Steer to Counteract the Tide 7.7.3 The Change of Course Needed to Maintain Track When Changing Speed in Tide 7.8 The Theory and Practice of Reflection Plotters 7.8.1 The Construction of the Reflection Plotter 7.8.2 Testing and Adjustment 7.8.3 Care and Maintenance 7.8.4 The Practical Use of Reflection Plotters 7.8.5 Changing Range Scale 7.8.6 The Use of the 'Free' EBL to Draw Parallel Lines 7.8.7 Fixed and Rotatable Surfaces - Use with a Ship's-Head-up Unstabilized Display 7.8.8 Flat and Concave Surfaces 7.8.9 Use in Conjunction with Parallel Indexing 7.8.10 Reflection Plotters and Raster-scan Displays 7.9 Manual Plotting - Accuracy and Errors 7.9.1 Accuracy of Bearings as Plotted 7.9.2 Accuracy of Ranges as Plotted 7.9.3 Accuracy of Own Ship's Speed 7.9.4 Accuracy of Own Ship's Course 7.9.5 Accuracy of the Plotting Interval 7.9.6 The Accuracy with Which CPA Can be Determined 7.9.7 The Consequences of Random Errors in Own Ship's Course and Speed 7.9.8 Summary 7.10 Errors Associated with the True-Motion Presentation 7.10.1 Incorrect Setting of the True-Motion Controls 7.10.2 Tracking Course Errors 7.10.3 Tracking Speed Errors 7.10.4 The Effect of Radial Display Nonlinearity 7.11 Radar Plotting Aids 7.11.1 The Radar Plotting Board 7.11.2 Threat Assessment Markers 7.11.3 The 'E' Plot 7.11.4 Intelligent Knowledge-Based Systems as Applied to Collision Avoidance 7.12 The Regulations for Preventing Collisions at Sea as Applied to Radar and ARPA 7.12.1 Introduction 7.12.2 Lookout - Rule 5 7.12.3 Safe Speed - Rule 6 7.12.4 Risk of Collision - Rule 7 7.12.5 Conduct of Vessels in Restricted Visibility - Rule 19 7.12.6 Action to Avoid Collision — Rule 8 7.12.7 The Cumulative Turn 7.12.8 Conclusion8 Navigation Techniques Using Radar and ARPA 8.1 Introduction 8.2 Identification of Targets and Chart Comparison 8.2.1 Long Range Target Identification 8.2.2 The Effect of Discrimination 8.2.3 Shadow Areas 8.2.4 Rise and Fall of Tide 8.2.5 Radar-Conspicuous Targets 8.2.6 Pilotage Situations 8.3 Position Fixing 8.3.1 Selection of Targets 8.3.2 Types of Position Line 8.4 Parallel Indexing 8.4.1 Introduction 8.4.2 Preparations and Precautions 8.4.3 Parallel Indexing, the Technique 8.4.4 Progress Monitoring 8.4.5 Parallel Indexing on a True-Motion Display 8.4.6 Modern Radar Navigation Facilities 8.4.7 Unplanned Parallel Indexing 8.4.8 Anti-Collision Manoeuvring While Parallel Indexing9 ARPA - Accuracy and Errors 9.1 Introduction 9.2 The Test Scenarios 9.3 The Accuracy of Displayed Data Required by the Performance Standard 9.4 The Classification of ARPA Error Sources 9.5 Errors That are Generated in the Radar Installation 9.5.1 Glint 9.5.2 Errors in Bearing Measurement 9.5.3 Errors in Range Measurement 9.5.4 The Effect of Random Gyro Compass Errors 9.5.5 The Effect of Random Log Errors 9.5.6 The Magnitude of Sensor Errors Specified in the Performance Standard 9.6 Errors in Displayed Data 9.6.1 Target Swop 9.6.2 Track Errors 9.6.3 The Effect on Vectors of Incorrect Course and Speed Input 9.6.4 The Effect on the PPC of Incorrect Data Input 9.7 Errors of Interpretation 9.7.1 Errors with Vector Systems 9.7.2 Errors with PPC and PAD Systems 9.7.3 The Misleading Effect of Afterglow 9.7.4 Accuracy of the Presented Data 9.7.5 Missed Targets10 Extracts from official Publications 10.1 Extract from Regulation 12, Chapter V of the IMO-SOLAS (1974) Convention as Amended to 1983 10.2 Extracts from IMO Resolutions A222(VII), A278(VIII), A477(XII) 10.2.1 Performance Standards for Navigational Radar Equipment Installed before 1 September 1984 10.2.2 Performance Standards for Navigational Radar Equipment Installed on or After 1 September 1984 10.3 Extract from IMO Resolution A422(XI), 10.3.1 Performance Standards for Automatic Radar Plotting Aids (ARPA) 10.4 Extracts from IMO Resolutions A423 (XI) and A277 (VIII), Radar Beacons, Transponders and Reflectors 10.4.1 Marine Uses of Radar Beacons and Transponders 10.4.2 Performance Standards for Radar Reflectors 10.5 Extract from United Kingdom Merchant Shipping Notice Ml 158, The Use of Radar including ARPA 10.6 Extracts from United Kingdom Statutory Instrument 1984, No. 1203Glossary of Acronyms and AbbreviationsIndex