AET Communication Systems 2 — Questions and Answers
Question 1: HF radio communication in aviation is primarily used for which purpose?
- Short-range ramp communications
- Oceanic and long-range en-route communications (Correct answer)
- Ground control taxi instructions
- Instrument approach guidance
Correct answer: Oceanic and long-range en-route communications
HF radio (2–30 MHz) uses ionospheric propagation to achieve communications over oceanic and polar routes beyond VHF line-of-sight range.
Question 2: What type of modulation is used by HF aviation voice transceivers?
- AM double sideband
- FM
- Single Sideband (SSB) (Correct answer)
- Pulse amplitude modulation
Correct answer: Single Sideband (SSB)
HF aviation radios use Single Sideband (SSB) modulation because it is more power-efficient and occupies less bandwidth than double-sideband AM.
Question 3: What is the function of a SATCOM system on a commercial aircraft?
- Provide radar weather data
- Enable satellite-based voice, data, and internet communication (Correct answer)
- Transmit transponder codes
- Support VOR navigation
Correct answer: Enable satellite-based voice, data, and internet communication
Aircraft SATCOM systems use geostationary or low-earth-orbit satellites to provide global voice, data, and passenger internet connectivity.
Question 4: Which connector type is most commonly used for VHF antenna connections in aircraft communication systems?
- BNC
- TNC
- BNC or TNC (50Ω coaxial) (Correct answer)
- XLR
Correct answer: BNC or TNC (50Ω coaxial)
VHF antenna coaxial connections in aviation typically use BNC or TNC 50-ohm coaxial connectors, with BNC most common in general aviation.
Question 5: What is a common symptom of a broken coaxial antenna feed line in a VHF COM system?
- No power to the radio
- Very short transmission range and reduced receive sensitivity (Correct answer)
- Stuck squelch
- Excessive audio distortion
Correct answer: Very short transmission range and reduced receive sensitivity
A broken or high-VSWR coaxial feed line causes significant signal loss, resulting in greatly reduced transmit range and receive sensitivity.
Question 6: What test instrument is used to verify antenna VSWR (Voltage Standing Wave Ratio) in aircraft communications?
- Oscilloscope
- Wattmeter/SWR meter (Correct answer)
- Multimeter
- Spectrum analyzer only
Correct answer: Wattmeter/SWR meter
A wattmeter or SWR meter measures forward and reflected RF power to calculate VSWR, confirming antenna system impedance matching.
AET Communication Systems 2
HF radio communication in aviation is primarily used for which purpose?