Avionic Systems Overview
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Which factor does NOT affect the range of VHF transmission?

  • Frequency of the transmission (correct)
  • Obstacles at the transmission site
  • Height of the receiver
  • Height of the transmitter

    • In HF communication, which of the following factors affects transmission range the least?

  • Transmission power
  • Time of day
  • Geographical location
  • Weather conditions (correct)

    • What is the primary use of HF communication?

  • Airborne entertainment
  • Flight safety notifications
  • Aircraft maintenance communication
  • Air Traffic Control (ATC) (correct)

    • Which component in the VHF system handles both audio transmission and frequency selection?

    <p>Control panel</p> Signup and view all the answers

    What is essential in an HF system to ensure efficient signal matching between the transceiver and antenna?

    <p>Coupler</p> Signup and view all the answers

    Which of the following statements about VHF and HF systems is incorrect?

    <p>VHF communication primarily uses sky wave propagation.</p> Signup and view all the answers

    In HF communication, what may disturb signal quality besides geographical location?

    <p>Time of year</p> Signup and view all the answers

    What component in the HF system directly guides audio to the flight interphone system?

    <p>De-modulator</p> Signup and view all the answers

    Which combination of characteristics is typically involved in the VHF system architecture?

    <p>Control panel, audio input, antenna</p> Signup and view all the answers

    What distinguishes the way HF communication achieves long-range capabilities compared to VHF?

    <p>Reliance on sky wave propagation</p> Signup and view all the answers

    What is the primary purpose of the SELCAL system in aviation?

    <p>To allow pilots to mute receivers until a specific code is transmitted</p> Signup and view all the answers

    Which frequency is designated for military rescue signals transmitted by an ELT?

    <p>243.0 MHz</p> Signup and view all the answers

    What component of the SELCAL system alerts the crew when a specific code is received?

    <p>The SELCAL lamp or switch</p> Signup and view all the answers

    Which of the following facts about the Emergency Locator Transmitter (ELT) is NOT true?

    <p>ELTs are designed to function only in water.</p> Signup and view all the answers

    What is a key feature of the RESCU 406 transmitter used in emergency situations?

    <p>It includes a long erecting antenna.</p> Signup and view all the answers

    Which SELCAL tone is assigned to the frequency of 794.3 Hz?

    <p>RED 'K'</p> Signup and view all the answers

    What action initiates the operation of the ELT when used in water?

    <p>Attaching the lanyard cord to a raft</p> Signup and view all the answers

    What type of signals does the RESCU 406 beacon transmit?

    <p>Both civil and military rescue signals</p> Signup and view all the answers

    What is the primary frequency range used for Very High Frequency (VHF) communications in aviation?

    <p>118-136 MHz</p> Signup and view all the answers

    What must a pilot do to ensure effective operation of the ELT during land use?

    <p>Position the antenna without any obstacles</p> Signup and view all the answers

    How long is the typical operation duration for an ELT after activation?

    <p>48 hours</p> Signup and view all the answers

    Which of the following systems is specifically used for air-to-air and air-to-ground communications in aviation?

    <p>VHF Communication</p> Signup and view all the answers

    What critical skill is required for a Singapore Aircraft Maintenance Engineer (AME) Licence applicant?

    <p>Ability to read, write and converse in English</p> Signup and view all the answers

    What does the Selective Calling System (SELCAL) primarily facilitate in aviation communications?

    <p>Selecting specific aircraft for communication</p> Signup and view all the answers

    What is the impact of VHF communication maintaining voice as its primary mode in various parts of the world?

    <p>Increased reliance on human operators</p> Signup and view all the answers

    Which statement about frequencies is true for High Frequency (HF) communication systems in aviation?

    <p>HF communication is primarily used for long-distance signaling.</p> Signup and view all the answers

    Who must pass the exams specified in the SAR Section 66 to obtain the Singapore AME license?

    <p>Singaporeans or permanent residents</p> Signup and view all the answers

    When considering the radius of a VHF signal in nautical miles, which factor is most relevant?

    <p>Antenna heights of receiver and transmitter</p> Signup and view all the answers

    What percentage does the semester examination comprise of in the overall assessment components for AVS?

    <p>50%</p> Signup and view all the answers

    Which communication method is currently the primary mode in aviation despite advancements in technology?

    <p>Voice modulation of radio waves</p> Signup and view all the answers

    Which of the following factors significantly influences the range of HF transmission?

    <p>Geographical location</p> Signup and view all the answers

    What is the primary function of the coupler in an HF system?

    <p>To match antenna impedance with the transceiver</p> Signup and view all the answers

    What is the typical impact of time of day on HF transmission?

    <p>Affects atmospheric conditions</p> Signup and view all the answers

    In the context of VHF communication, what role does the frequency control panel play?

    <p>Enables frequency selection for transmission</p> Signup and view all the answers

    Which of the following is a characteristic of VHF transmission affected by obstacles?

    <p>Signal reflection and scattering</p> Signup and view all the answers

    What distinguishes HF communication from VHF communication in terms of range?

    <p>HF utilizes sky wave for long-range communication</p> Signup and view all the answers

    Which component in the VHF system is responsible for guiding audio communication?

    <p>De-modulator</p> Signup and view all the answers

    How does the season of the year affect HF transmission?

    <p>Affects the ionosphere layers, altering signal propagation</p> Signup and view all the answers

    What is a critical impact of transmission power at both aircraft and ground station on communication?

    <p>Affects the overall communication range</p> Signup and view all the answers

    Which system component effectively combines the tasks of transmitting and receiving signals in aviation?

    <p>Transceiver</p> Signup and view all the answers

    Which aspect of VHF communication is essential for facilitating air traffic control?

    <p>Line of sight by direct wave</p> Signup and view all the answers

    Which of the following is a requirement for obtaining a Singapore Aircraft Maintenance Engineer (AME) Licence?

    <p>Being at least twenty-one years old</p> Signup and view all the answers

    What is a significant advantage of voice communication in aviation?

    <p>It facilitates immediate understanding and response.</p> Signup and view all the answers

    Which factor mainly affects the effective range of VHF communication?

    <p>Antenna heights of receiver and transmitter</p> Signup and view all the answers

    What is the main operational method for communication in aviation today?

    <p>Voice modulation of radio waves</p> Signup and view all the answers

    Which type of communication system requires operators to have practical experience as outlined in SAR Section 66?

    <p>Singapore Aircraft Maintenance Engineer (AME) Licence</p> Signup and view all the answers

    What does the concept of 'Selective Calling System (SELCAL)' primarily provide in aviation?

    <p>Individual alerts for aircraft communication</p> Signup and view all the answers

    What percentage of the overall assessment for AVS is comprised by the semester examination?

    <p>50%</p> Signup and view all the answers

    What is the purpose of the Emergency Locator Transmitter (ELT) in aviation?

    <p>To locate aircraft in case of emergencies</p> Signup and view all the answers

    What is the function of the SELCAL system in aviation communication?

    <p>It enables pilots to mute their radio until their specific code is received.</p> Signup and view all the answers

    Which two frequencies are designated for rescue signals transmitted by the RESCU 406?

    <p>121.5 MHz and 243.0 MHz</p> Signup and view all the answers

    What type of code does the SELCAL system assign to each aircraft?

    <p>A four-letter code</p> Signup and view all the answers

    What key function is activated in the cockpit when the SELCAL code is received?

    <p>The alarm or alert system for communication</p> Signup and view all the answers

    Which part of the Emergency Locator Transmitter (ELT) is responsible for activating the distress signal in water?

    <p>The water-activated switch in the liquid container</p> Signup and view all the answers

    In land operation, what substance is necessary for activating the ELT transmitter?

    <p>Fresh or salt water</p> Signup and view all the answers

    How long can the Emergency Locator Transmitter (ELT) typically emit signals after it is activated?

    <p>48 hours</p> Signup and view all the answers

    What type of communications does the SELCAL system specifically enhance for pilots on long-haul flights?

    <p>Voice transmissions</p> Signup and view all the answers

    What component in the SELCAL system is responsible for decoding the transmitted signals?

    <p>SELCAL Decoder</p> Signup and view all the answers

    What is the primary benefit of the SELCAL system for pilots flying in areas with significant radio interference?

    <p>Ability to ignore unimportant transmissions</p> Signup and view all the answers

    Study Notes

    Avionic Systems Overview

    • Avionic systems are crucial for aircraft operation
    • Part 1 focuses on avionics (VHF/HF, ILS, VOR, ADF, FMS, and GPS)
    • Part 2 covers radar (primary, weather, and secondary)

    Assessment

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

    Singapore Aircraft Maintenance Engineer (AME) Licence Application

    • Applicants must be Singaporean or permanent residents
    • Minimum age is 21 years
    • Fluency in English is required (reading, writing, and conversation)
    • Employment by an organization servicing Singapore registered aircraft is needed
    • Practical experience as specified in SAR Section 66 is required
    • Successful completion of examinations for the licence category is essential
    • No significant disabilities affecting technical skill or judgement

    Chapter 1: VHF/HF Communication Systems

    • Aviation communication is primarily by voice modulation of radio waves
    • Data transfer is a future trend
    • Voice communication remains vital for safe air traffic

    Learning Outcomes

    • Airborne VHF (Very High Frequency) communication
    • Airborne HF (High Frequency) communication
    • Selective Calling System (SELCAL) concept
    • Emergency Locator Transmitter (ELT) operation

    VHF Communication

    • VHF communication is line-of-sight, using direct waves
    • Short-range communication between aircraft and ground stations is a key feature
    • Primary use is for Air Traffic Control (ATC)
    • Operating frequency range is 118-136 MHz

    VHF Communication Range Calculation

    • Range (nautical miles) = 1.25 * √(transmitter antenna height + receiver antenna height)
      • Heights are in feet

    Factors Affecting VHF Range

    • Transmitter and ground station power
    • Transmitter antenna height
    • Receiver antenna height
    • Obstacles blocking the signal path

    VHF System Components

    • Frequency control panel
    • Flight interphone system with microphone input
    • Transceiver (transmitter + receiver)
    • Antenna
    • RF-coax line for signal transmission

    VHF System Diagram

    • Shows the flow of signals between components.

    Selective Calling (SELCAL)

    • Allows pilots to mute their receivers until ATC sends a specific code for their aircraft
    • This reduces the need for constant radio monitoring
    • Important for reducing pilot fatigue
    • Used for HF communication as well as VHF
    • Assigned codes in (Hz) are provided.
    • A rack-mounted Selcal encoder is used.

    SELCAL System Components

    • Decoder (five channels)
    • Tone selector (delivers audio input)
    • Selcal lamps/switches (activate alert)

    Emergency Locator Transmitter (ELT)

    • Radio devices carried on aircraft
    • Activated in emergencies to help locate crash sites
    • Aids in survival by rescue personnel
    • Includes components: Lanyard cord, Antenna, Plastic bag, Battery

    RESCU 406 ELT

    • Water-operable
    • Includes components: Long erecting antenna, Lanyard cord, Plastic water bag
    • Transmits two rescue signals (Civil Rescue: 121.5 MHz, Military Rescue: 243.0 MHz)

    ELT Water Operation

    • Tie the lanyard cord of the ELT to a raft
    • Submerge the ELT in the water
    • ELT automatically starts broadcasting distress frequency

    ELT Land Operation

    • Properly erect and position the antenna
    • Ensure clear sightline for signal transmission
    • Fill the liquid reservoir (fresh or salt water)
    • Normal transmission duration for ELT is 48 hours

    ELT Example 1-2

    • Calculate current consumption for a 240 mAh Nickel-Cadmium battery used for 24 hours in an ELT.
    • Calculation results in 10 mA for current consumption.

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    Description

    This quiz explores the critical aspects of avionic systems, focusing on communication technologies such as VHF/HF, ILS, VOR, ADF, FMS, and GPS. Additionally, it covers various radar systems including primary, weather, and secondary radar. Ideal for students pursuing a Singapore Aircraft Maintenance Engineer License.

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