Practice Test Geeks(AET) Aircraft Electronics Technician Practice Test
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Communication Systems Flashcards

7 cards from real AET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Communication Systems flashcards as text

  1. An HF antenna coupler (ATU) is required because:

    Answer: Antenna impedance varies widely across HF frequencies and must be matched to the transmitter

    HF antennas are electrically short relative to the wavelength at many HF frequencies, so the ATU performs impedance matching to maximize power transfer.

  2. ACARS (Aircraft Communications Addressing and Reporting System) transmits data using:

    Answer: VHF AM with GFSK data subcarrier (VDL Mode 0/A) or VDL Mode 2

    Classic ACARS uses 2400 bps GFSK data over VHF AM channels, while the newer VDL Mode 2 standard uses GFSK at 31.5 kbps over VHF.

  3. Which Federal Aviation Regulation (FAR) part governs the installation and airworthiness of aircraft communication equipment?

    Answer: FAR Part 43 and Part 91

    FAR Part 43 covers maintenance and alteration of avionics, while Part 91 (and 121/135 as applicable) specifies equipment requirements and operational rules.

  4. A VHF communication radio is transmitting on the correct frequency but the transmission sounds distorted at receiving stations. The MOST likely cause is:

    Answer: Audio input overdriving the modulator causing over-modulation

    Over-modulation occurs when excessive audio levels drive the modulator beyond 100%, producing harmonic splatter and distorted audio at receivers.

  5. Emergency Locator Transmitters (ELTs) required under TSO-C126b operate on which frequency?

    Answer: 406 MHz (with optional 121.5 MHz homing)

    Modern 406 MHz ELTs transmit a digital coded burst processed by COSPAS-SARSAT satellites, and typically also transmit on 121.5 MHz for local homing.

  6. In a typical aircraft audio management system, a 'hot mic' mode means:

    Answer: The crew microphone is continuously open without requiring a PTT press

    Hot mic enables voice-activated (VOX) or continuous microphone transmission, typically used in crew oxygen mask situations where PTT operation is impractical.

  7. What is the primary advantage of 8.33 kHz VHF channel spacing over legacy 25 kHz spacing in European airspace?

    Answer: Triples the number of available VHF communication channels

    8.33 kHz spacing increases the number of usable VHF channels from approximately 760 to over 2280 in the 118–136.975 MHz band, addressing frequency congestion.