A.10.1 BASIC RADIO THEORY
a) Electromagnetic Waves
- Nature of electromagnetic radiation
- Relationship between electric and magnetic fields
- Velocity of propagation (speed of light)
- Frequency (f), wavelength (λ), period, cycle
- Phase and phase difference
- Amplitude and its significance
- Frequency spectrum and allocation
- Frequency bands (ELF to EHF; aviation-relevant bands: LF, MF, HF, VHF, UHF, SHF)
Modulation & Signal Characteristics
- Carrier wave concept
- Modulation and demodulation principles
- Amplitude Modulation (AM)
- Modulation index
- Advantages and limitations in aviation
- Frequency Modulation (FM)
- Deviation and bandwidth
- Comparison with AM
- Pulse modulation (basic concept)
- Sidebands
- Upper and Lower Sidebands
- Double Sideband (DSB)
- Single Sideband (SSB)
- Bandwidth requirements
- Designation of emission (ITU emission designators)
- Signal-to-noise ratio (SNR) and its operational significance
b) Antennas
- Basic antenna theory
- Antenna characteristics
- Gain
- Efficiency
- Directivity
- Radiation pattern
- Polarisation
- Vertical
- Horizontal
- Circular
- Polar diagrams (interpretation and use)
- Types of antennas used in aviation
- Dipole
- Monopole
- Loop
- Directional antennas
- Parabolic reflector
c) Wave Propagation
- Ground waves (surface waves)
- Direct waves (line-of-sight propagation)
- Sky waves (ionospheric reflection)
- Ionosphere structure and layers (D, E, F layers)
- Critical angle and critical frequency
- Skip distance
- Dead space (skip zone)
- Refraction
- Fading (selective and multipath fading)
- Factors affecting propagation:
- Reflection
- Absorption
- Attenuation
- Coastal refraction effects
- Mountain effect
- Static interference
A.10.2 AUTOMATIC DIRECTION FINDER (ADF)
a) ADF Loop Theory
- Basic principle of direction finding
- Loop antenna theory
- Figure-of-eight polar diagram
- Null position concept
- Sense antenna function
- Elimination of 180° ambiguity
- Combination of loop and sense antenna
Rotating and Fixed Loop Antennas
- Manually rotated loop systems
- Automatic (fixed loop) ADF systems
- Bearing determination process
Principles of Operation
- NDB transmission characteristics
- Frequency band (LF/MF)
- Non-directional transmission
- ADF receiver components
- Bearing determination relative to aircraft heading
- Magnetic bearing to station (QDM)
- Magnetic bearing from station (QDR)
- Relative bearing
Presentation and Interpretation
- Relative bearing indication
- Magnetic bearing interpretation
- Homing vs tracking
- Wind effect and drift correction
- Station passage recognition
Coverage
- Ground wave propagation characteristics
- Day and night effect
- Coastal refraction influence
Range
- Dependence on transmitter power
- Surface conductivity
- Atmospheric conditions
- Night effect range increase
Errors and Accuracy
- Quadrantal error
- Dip error (bank error)
- Night effect
- Coastal refraction
- Mountain effect
- Static interference
- Electrical interference
Factors Affecting Range and Accuracy
- Ionospheric conditions
- Terrain
- Thunderstorms
- Aircraft attitude
- Receiver calibration
RBI and RMI
- RBI (Relative Bearing Indicator)
- Fixed card presentation
- Relative bearing reading only
- RMI (Radio Magnetic Indicator)
- Rotating compass card
- Direct magnetic bearing display
- Dual-needle capability (ADF/VOR integration)
A.10.3 VHF OMNI-DIRECTIONAL RANGE (VOR)
Principles of Operation
- VHF frequency band (108.00–117.95 MHz)
- Line-of-sight propagation
- Reference phase and variable phase signals
- Phase comparison principle
- Radial concept (FROM station)
- Bearing determination
Presentation and Interpretation
- OBS (Omni Bearing Selector)
- TO/FROM indication
- Radial interception
- Tracking procedures
- Station passage identification
Coverage
- Line-of-sight limitations
- Classification of VOR stations:
- Terminal (T-VOR)
- Low altitude (L-VOR)
- High altitude (H-VOR)
Range
- Dependence on altitude
- Service volume categories
- Geographical limitations
Errors and Accuracy
- Site error
- Scalloping
- Bends
- Propagation error
- Instrument error
Factors Affecting Range and Accuracy
- Terrain shielding
- Multipath interference
- Atmospheric conditions
- Aircraft altitude
CDI and RMI
CDI (Course Deviation Indicator)
- Lateral deviation indication
- Sensitivity (dots displacement)
- Full-scale deflection values
- Intercept angles
RMI (Radio Magnetic Indicator)
- Bearing pointer operation
- Integration with magnetic heading
- Situational awareness enhancement
Doppler VOR
- Principle of Doppler effect application
- Frequency modulation simulation
- Advantages over conventional VOR
- Reduced site error
- Improved accuracy
- Identification characteristics
A.10.4 DISTANCE MEASURING EQUIPMENT (DME)
- Principles of operation
- Pulse interrogation and reply
- Time delay measurement
- Slant range concept
- Presentation and interpretation
- Distance display
- Groundspeed and time-to-station (if applicable)
- Coverage characteristics
- Maximum and practical range
- Errors and accuracy
- Slant range error
- Multipath error
- Factors affecting range and accuracy
A.10.5 BASIC RADAR PRINCIPLES
- Primary radar principle
- Pulse techniques
- Radar terminology:
- Pulse Repetition Frequency (PRF)
- Pulse Repetition Time (PRT)
- Pulse length
- Duty cycle
- Peak and average power
- Range resolution
- Azimuth resolution
A.10.6 GROUND RADAR
- Principles of operation
- Presentation and interpretation (PPI display)
- Coverage
- Range determination
- Errors and accuracy
- Factors affecting range and accuracy
- Ground clutter
- Sea clutter
- Shadowing
- Anomalous propagation
- Application for navigation
C.10.7 SECONDARY SURVEILLANCE RADAR (SSR)
- Principles of operation
- Interrogation and reply system
- Presentation and interpretation
- Modes and codes:
- Mode A
- Mode C
- Mode S
- Transponder operation
- Identification features
A.10.8 AIRBORNE WEATHER RADAR
- Principles of operation
- Pulse radar
- Reflectivity concept
- Presentation and interpretation
- Tilt control
- Gain control
- Colour coding
- Coverage
- Range limitations
A.10.9 RADIO ALTIMETER
- Principles of operation
- Frequency-modulated continuous wave (FMCW) principle
- Operating frequency band
- Presentation and interpretation
- Errors and accuracy
- Terrain reflectivity
- Bank angle effects
- Signal absorption
A.10.10 EMERGENCY LOCATOR TRANSMITTER (ELT)
- Principles of operation
- Operating frequencies
- 121.5 MHz
- 406 MHz
- COSPAS-SARSAT system overview
- Testing procedures and limitations
A.10.11 AREA NAVIGATION (RNAV)
VOR/DME Area Navigation
- Principle of operation
- Waypoint generation
- Advantages and disadvantages
- Accuracy
- Reliability
- Coverage limitations
- Required flight deck equipment
A.10.12 SATELLITE ASSISTED NAVIGATION (GNSS / NAVSTAR GPS)
- System components
- Space segment
- Control segment
- User segment
- Principle of operation
- Trilateration
- Pseudorange measurement
- Advantages and disadvantages
- Navigation system performance requirements
- Accuracy
- Integrity
- Continuity
- Availability
- Reliability and integrity monitoring (RAIM concept)
- Authorisation and documentation requirements
- Errors and limitations
- Satellite clock error
- Ionospheric error
- Multipath
- Geometry (GDOP)
- Human factors and GNSS
