- •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
14 Secondary Surveillance Radar (SSR)
SSR Summary
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SSR |
Requires Transponder in aircraft and Interrogator at ground |
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station. |
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Advantages over primary radar. |
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Aerial on top of primary radar. |
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Displays call sign, pressure altitude or FL, ground speed, destination. |
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Frequencies |
Ground station transmits narrow beam at 1030 MHz and receives at |
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1090 MHz. |
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Aircraft receives at 1030 MHz and transmits omni-directionally at |
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1090 MHz. (in the UHF band). |
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Modes/Replies |
Mode A |
For identity (8 µs interrogation pulse spacing) 12 reply |
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pulses give 4096 combinations (20.3 µs spacing between |
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framing pulses). Extra pulse (SPI) for squawk Ident (for |
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20 s). |
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Mode C |
For automatic pressure-altitude (21 µs interrogation |
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spacing). Transmitted and displayed every 100 ft (± 50 ft |
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from given level). Switch off if difference > 300 ft (200 ft |
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UK). |
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Special codes |
7700 – emergency |
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7600 – radio failure |
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7500 – unlawful interference |
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Disadvantages of SSR |
Garbling - overlapping replies if aircraft < 1.7 NM apart |
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Secondary |
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Fruiting - interference caused by replies to other interrogation. |
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Limited codes (4096). |
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Surveillance |
Mode S Features |
Selective addressing. Nearly 17 million codes from 24-bit address. |
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Data link air-to-ground, ground-to-air, air-to-air. |
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Height read-out in increments of 25 ft. |
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Radar |
Interrogation modes |
All Call - mode S. |
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Broadcast (no reply). |
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(SSR) |
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Selective calling (unique aircraft address). |
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Intermode - A/C/S All call. |
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Benefits of mode S |
Unambiguous aircraft identification. |
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Improved surveillance (eliminates garble, resolves overinterrogation |
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and reflections). |
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Improved situation awareness for radar controller. |
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No code shortage. |
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Reduced R/T. |
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Improved short term conflict alert. |
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238
Questions 14
Questions
1.The special SSR codes are as follows: emergency ............... , radio failure ................ , unlawful interference with the conduct of the flight ................
a. |
7700 |
7600 |
7500 |
b. |
7700 |
7600 |
7500 |
c. |
7600 |
7500 |
7700 |
d. |
7500 |
7600 |
7700 |
2.Secondary Surveillance Radar is a form of .............. radar with ..............type emissions operating in the .............. band.
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primary |
pulse |
SHF |
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b. |
primary |
pulse |
UHF |
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c. |
secondary |
FM |
SHF |
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d. |
secondary |
pulse |
UHF |
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3. |
If the SSR transponder IDENT button is pressed: |
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a. |
it causes a momentary distinctive display to appear on the controller’s screen |
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b. |
an identification pulse is automatically and continuously transmitted for 20 |
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seconds, 4.35 µs before the last framing pulse |
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c. |
an identification pulse is automatically and continuously transmitted for 10 |
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seconds, 4.35 µs after the last framing pulse |
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d. |
an identification pulse is automatically and continuously transmitted for 20 |
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seconds, 4.35 µs after the last framing pulse |
Questions |
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4. |
When using SSR the ground controller will ask the pilot to cancel mode C if there is a |
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discrepancy of more than ............... between the altitude detected by the radar from |
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the reply pulses and the altitude reported by the pilot read from an altitude with the |
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subscale set to ............... |
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a. |
100 ft |
Regional QNH |
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b. |
300 ft |
1013 HPa |
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c. |
50 ft |
1013 HPa |
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d. |
300 ft |
Regional QNH |
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5.Secondary radars require:
a.a target which will respond to the interrogation, and this target will always be an aircraft
b.a target which will respond to the interrogation, and this target will always be ground based
c.a target which will respond to the interrogation, and this target may be either an aircraft or a ground based transponder
d.a quiescent target
239
14 Answers
Answers
1 |
2 |
3 |
4 |
5 |
a |
d |
d |
b |
c |
Answers 14
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