- •Textbook Series
- •Contents
- •1 Properties of Radio Waves
- •Introduction
- •The Radio Navigation Syllabus
- •Electromagnetic (EM) Radiation
- •Polarization
- •Radio Waves
- •Wavelength
- •Frequency Bands
- •Phase Comparison
- •Practice Frequency (
- •Answers to Practice Frequency (
- •Questions
- •Answers
- •2 Radio Propagation Theory
- •Introduction
- •Factors Affecting Propagation
- •Propagation Paths
- •Non-ionospheric Propagation
- •Ionospheric Propagation
- •Sky Wave
- •HF Communications
- •Propagation Summary
- •Super-refraction
- •Sub-refraction
- •Questions
- •Answers
- •3 Modulation
- •Introduction
- •Keyed Modulation
- •Amplitude Modulation (AM)
- •Single Sideband (SSB)
- •Frequency Modulation (FM)
- •Phase Modulation
- •Pulse Modulation
- •Emission Designators
- •Questions
- •Answers
- •4 Antennae
- •Introduction
- •Basic Principles
- •Aerial Feeders
- •Polar Diagrams
- •Directivity
- •Radar Aerials
- •Modern Radar Antennae
- •Questions
- •Answers
- •5 Doppler Radar Systems
- •Introduction
- •The Doppler Principle
- •Airborne Doppler
- •Janus Array System
- •Doppler Operation
- •Doppler Navigation Systems
- •Questions
- •Answers
- •6 VHF Direction Finder (VDF)
- •Introduction
- •Procedures
- •Principle of Operation
- •Range of VDF
- •Factors Affecting Accuracy
- •Determination of Position
- •VDF Summary
- •Questions
- •Answers
- •7 Automatic Direction Finder (ADF)
- •Introduction
- •Non-directional Beacon (NDB)
- •Principle of Operation
- •Frequencies and Types of NDB
- •Aircraft Equipment
- •Emission Characteristics and Beat Frequency Oscillator (BFO)
- •Presentation of Information
- •Uses of the Non-directional Beacon
- •Plotting ADF Bearings
- •Track Maintenance Using the RBI
- •Homing
- •Tracking Inbound
- •Tracking Outbound
- •Drift Assessment and Regaining Inbound Track
- •Drift Assessment and Outbound Track Maintenance
- •Holding
- •Runway Instrument Approach Procedures
- •Factors Affecting ADF Accuracy
- •Factors Affecting ADF Range
- •Accuracy
- •ADF Summary
- •Questions
- •Answers
- •8 VHF Omni-directional Range (VOR)
- •Introduction
- •The Principle of Operation
- •Terminology
- •Transmission Details
- •Identification
- •Monitoring
- •Types of VOR
- •The Factors Affecting Operational Range of VOR
- •Factors Affecting VOR Beacon Accuracy
- •The Cone of Ambiguity
- •Doppler VOR (DVOR)
- •VOR Airborne Equipment
- •VOR Deviation Indicator
- •Radio Magnetic Indicator (RMI)
- •Questions
- •In-flight Procedures
- •VOR Summary
- •Questions
- •Annex A
- •Annex B
- •Annex C
- •Answers
- •Answers to Page 128
- •9 Instrument Landing System (ILS)
- •Introduction
- •ILS Components
- •ILS Frequencies
- •DME Paired with ILS Channels
- •ILS Identification
- •Marker Beacons
- •Ground Monitoring of ILS Transmissions
- •ILS Coverage
- •ILS Principle of Operation
- •ILS Presentation and Interpretation
- •ILS Categories (ICAO)
- •Errors and Accuracy
- •Factors Affecting Range and Accuracy
- •ILS Approach Chart
- •ILS Calculations
- •ILS Summary
- •Questions
- •Answers
- •10 Microwave Landing System (MLS)
- •Introduction
- •ILS Disadvantages
- •The MLS System
- •Principle of Operation
- •Airborne Equipment
- •Question
- •Answer
- •11 Radar Principles
- •Introduction
- •Types of Pulsed Radars
- •Radar Applications
- •Radar Frequencies
- •Pulse Technique
- •Theoretical Maximum Range
- •Primary Radars
- •The Range of Primary Radar
- •Radar Measurements
- •Radar Resolution
- •Moving Target Indication (MTI)
- •Radar Antennae
- •Questions
- •Answers
- •12 Ground Radar
- •Introduction
- •Area Surveillance Radars (ASR)
- •Terminal Surveillance Area Radars
- •Aerodrome Surveillance Approach Radars
- •Airport Surface Movement Radar (ASMR)
- •Questions
- •Answers
- •13 Airborne Weather Radar
- •Introduction
- •Component Parts
- •AWR Functions
- •Principle of Operation
- •Weather Depiction
- •Control Unit
- •Function Switch
- •Mapping Operation
- •Pre-flight Checks
- •Weather Operation
- •Colour AWR Controls
- •AWR Summary
- •Questions
- •Answers
- •14 Secondary Surveillance Radar (SSR)
- •Introduction
- •Advantages of SSR
- •SSR Display
- •SSR Frequencies and Transmissions
- •Modes
- •Mode C
- •SSR Operating Procedure
- •Special Codes
- •Disadvantages of SSR
- •Mode S
- •Pulses
- •Benefits of Mode S
- •Communication Protocols
- •Levels of Mode S Transponders
- •Downlink Aircraft Parameters (DAPS)
- •Future Expansion of Mode S Surveillance Services
- •SSR Summary
- •Questions
- •Answers
- •15 Distance Measuring Equipment (DME)
- •Introduction
- •Frequencies
- •Uses of DME
- •Principle of Operation
- •Twin Pulses
- •Range Search
- •Beacon Saturation
- •Station Identification
- •VOR/DME Frequency Pairing
- •DME Range Measurement for ILS
- •Range and Coverage
- •Accuracy
- •DME Summary
- •Questions
- •Answers
- •16 Area Navigation Systems (RNAV)
- •Introduction
- •Benefits of RNAV
- •Types and Levels of RNAV
- •A Simple 2D RNAV System
- •Operation of a Simple 2D RNAV System
- •Principle of Operation of a Simple 2D RNAV System
- •Limitations and Accuracy of Simple RNAV Systems
- •Level 4 RNAV Systems
- •Requirements for a 4D RNAV System
- •Control and Display Unit (CDU)
- •Climb
- •Cruise
- •Descent
- •Kalman Filtering
- •Questions
- •Appendix A
- •Answers
- •17 Electronic Flight Information System (EFIS)
- •Introduction
- •EHSI Controller
- •Full Rose VOR Mode
- •Expanded ILS Mode
- •Full Rose ILS Mode
- •Map Mode
- •Plan Mode
- •EHSI Colour Coding
- •EHSI Symbology
- •Questions
- •Appendix A
- •Answers
- •18 Global Navigation Satellite System (GNSS)
- •Introduction
- •Satellite Orbits
- •Position Reference System
- •The GPS Segments
- •The Space Segment
- •The Control Segment
- •The User Segment
- •Principle Of Operation
- •GPS Errors
- •System Accuracy
- •Integrity Monitoring
- •Differential GPS (DGPS)
- •Combined GPS and GLONASS Systems
- •Questions
- •Answers
- •19 Revision Questions
- •Questions
- •Answers
- •Specimen Examination Paper
- •Appendix A
- •Answers to Specimen Examination Paper
- •Explanation of Selected Questions
- •20 Index
Chapter
14
Secondary Surveillance Radar (SSR)
Introduction |
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Advantages of SSR . . . . . . . . . . . . |
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SSR Display |
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SSR Frequencies and Transmissions . . . . . . |
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Modes . . . . . . . . . . . . . . . . . |
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Mode C . . . . . . . . . . . . . . . . |
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SSR Operating Procedure |
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Special Codes . . . . . . . . . . . . . . |
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Disadvantages of SSR |
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Mode S |
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Pulses . . . . . . . . . . . . . . . . . |
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Benefits of Mode S . . . . . . . . . . . . |
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Communication Protocols . . . . . . . . . . |
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Levels of Mode S Transponders . . . . . . . . |
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Downlink Aircraft Parameters (DAPS) |
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Future Expansion of Mode S Surveillance Services . |
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SSR Summary . . . . . . . . . . . . . . |
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Questions . . . . . . . . . . . . . . . . |
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14 Secondary Surveillance Radar (SSR)
(SSR) Radar Surveillance Secondary 14
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Secondary Surveillance Radar (SSR) |
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Introduction |
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Primary radar relies on the reception of a reflected pulse i.e. the echo of the transmitted pulse. |
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Secondary radar, on the other hand, receives pulses transmitted by the target in response to |
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interrogation pulses. Secondary surveillance radar (SSR) is one type of secondary radar system; |
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DME is another such system that will be discussed in Chapter 15. |
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Both primary and secondary surveillance radars are used to track the progress of an aircraft. |
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Primary radar provides better bearing and range information of an aircraft than SSR but its |
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biggest disadvantage is the lack of positive, individual aircraft identification; this is required |
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for adequate safe control by ATC, particularly in crowded airspace. Primary radars also require |
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higher transmitter power outputs for the two-way journey of the single pulses. |
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SSR requires an aircraft to be fitted with a transmitter/receiver, called a transponder. The |
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pilot will set a four-figure code allocated by ATC and the transponder will transmit information |
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automatically, in pulse coded form, when it is interrogated by the ground station called the |
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interrogator. The transmissions are therefore only one way from transmitter to receiver. |
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Advantages of SSR |
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SSR has the following advantages over primary radar: |
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• requires much less transmitting power to provide coverage up to 200 to 250 NM. |
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• is not dependent on an aircraft’s echoing area or aspect. |
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• gives clutter free responses as it is does not rely on returning reflected pulses. |
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Radar |
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• positively identifies an aircraft’s primary response by displaying its code and call sign |
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alongside. |
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• indicates an aircraft’s track history, speed, altitude and destination. |
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• can indicate on a controller’s screen that an aircraft has an emergency, has lost radio |
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communications or is being hi-jacked. |
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Thus when SSR is used in conjunction with primary radar, the advantages of both systems are |
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realized. The two radars are therefore usually co-located as shown in Figures 14.1 and 14.2. |
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SSR Display |
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The SSR information is displayed in combination with the primary radar information on the |
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same screen as shown in Figure 14.3. This includes the call sign or flight number, pressure |
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altitude or flight level, ground speed and destination. |
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14 Secondary Surveillance Radar (SSR)
(SSR) Radar Surveillance Secondary 14
Figure 14.1 SSR aerial mounted on top of a 23 cm primary radar aerial
Figure 14.2 Primary and secondary radar used for ATC
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Secondary Surveillance Radar (SSR) 14
Secondary Surveillance Radar (SSR) 14
Figure 14.3 A radar display showing positions of aircraft in the London TMA
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