Avionic Systems Overview and Communication

Avionic Systems Overview

• Avionics systems include VHF/HF, ILS, VOR, ADF, FMS, and GPS.
• Radar systems include primary, weather, and secondary radar.

Assessment

• Semester Examination: 50%
• Mid-Semester Test: 20%
• Lab Test: 10%
• Lab Quiz: 10%
• General Performance: 10%

Singapore Aircraft Maintenance Engineer (AME) Licence Application Requirements

• Applicant must be at least 21 years old.
• Applicant must be a Singaporean or permanent resident.
• Applicant must be able to read, write, and converse in English.
• Applicant must be employed by an organization that operates or services Singapore-registered aircraft.
• Applicant must have the practical experience specified in SAR Section 66 and have passed the prescribed examinations for the license category.
• Applicant must not have any disability that could negatively affect technical skills or judgment.

Chapter 1: VHF/HF Communication Systems

• Aviation communication primarily uses voice modulation of radio waves.
• Future communication may utilize data transfer without human voice.
• Voice communication remains essential for safe air traffic control.

Learning Outcomes

• Airborne VHF Communication
• Airborne HF Communication
• Concept of Selective Calling System (SELCAL)
• Operation of Emergency Locator Transmitter (ELT)

VHF Communication

• VHF communication is line-of-sight, using direct waves.
• It provides short-range air-to-air and air-to-ground voice communication.
• Its primary use is for Air Traffic Control (ATC).
• The VHF band is 118-136 MHz.

VHF Communication Range

• Range (R) is calculated as 1.25 * (√H_r + √H_t).
• R is in nautical miles.
• H_r and H_t are the receiver and transmitter antenna heights in feet.
• Example: A VHF signal from an aircraft at 12,000ft could be received by an aircraft at 9,000 feet up to 255 nautical miles.

Factors Affecting VHF Transmission Range

• Transmitter power (aircraft and ground station).
• Transmitter antenna height.
• Receiver antenna height.
• Obstacles blocking the signal.

VHF System Components

• Frequency control panel.
• Flight interphone system (microphone).
• Transceiver (transmitter + receiver).
• Antenna.
• RF coax line.
• Audio is routed to interphone and SELCAL.
• Flight recorder system acknowledges transmission.

HF Communication

• HF communication uses sky waves for long-range voice communication.
• Primarily for Air Traffic Control (ATC).
• The HF band is 2-22 MHz.

Factors Affecting HF Transmission Range

• Transmitter power (aircraft and ground station).
• Time of day.
• Season of the year.
• Ionospheric disturbance.
• Geographical locations.
• Frequency in use.

HF System Components

• Frequency and power control panel for frequency selection and power settings.
• Flight interphone system for audio input.
• Transceiver (transmitter + receiver).
• Coupler (matching network for antenna).

Selective Calling (SELCAL)

• Pilots previously had to listen to radio continuously.
• SELCAL mutes the receiver until ATC transmits a code for a specific aircraft.
• SELCAL uses tones for specific aircraft identification.

SELCAL Tone Allocation

• Includes a specific tone for each aircraft designation.

SELCAL System Components

• Decoder (five channels).
• Tone selector (routing VHF/HF to decoder).
• Selcal lamp/switches (warning alarm for code reception).

Emergency Locator Transmitter (ELT)

• ELTs are radio devices for aircraft emergency use.
• ELT activation transmits signals to locate crash sites.
• ELTs use for rescue operations.

RESCU 406

• A programmable compact transmitter.
• Battery workable in water.
• Has a lanyard card, antenna, plastic water bag.
• Transmits two kinds of rescue signals (Civil and Military).
• Civil frequencies are 121.5 MHz.
• Military Frequencies are 243.0 MHz

ELT Water Operation

• Unroll and tie lanyard card to raft, place ELT in water.
• Transmits automatically upon immersion.

ELT Land Operation

• Erect antenna properly, position antenna without obstacles, pour liquids into container to activate water-activated switch.
• Ensure battery casing end is inserted into liquid container so the beacon transmits effectively

ELT Current Consumption Example

• Calculate current consumption for ELT using a Nickel-Cadmium battery with a 240 mAh rating. (Example provided).

Additional Notes

• Given information suggests a course on Avionic Systems.
• VHF diagrams and diagrams provided.
• HF diagrams and diagrams provided.

This quiz covers key concepts in avionic systems, including VHF/HF, radar systems, and communication technologies. It also includes requirements for the Singapore Aircraft Maintenance Engineer licence. Test your knowledge on aviation systems and licensing criteria.