Frequency Bands & Their Aviation UsesRadio Telephony — DGCA CPL practice questions
Question 1 of 15
Each radio band differs from the next by a factor of:
All 15 questions — Frequency Bands & Their Aviation Uses
Radio Telephony · DGCA CPL. The correct option is marked on each.
Q1. Each radio band differs from the next by a factor of:
- A.2
- B.5
- C.10✓
- D.100
Why: Bands run in decades — each is ten times the previous in frequency.
Q2. Aviation VHF communication uses which modulation?
- A.AM✓
- B.FM
- C.SSB
- D.PCM
Why: M. VHF voice uses AM; HF long-range uses SSB.
Q3. Long-range oceanic voice communication uses:
- A.VHF AM
- B.HF SSB (sky wave)✓
- C.UHF
- D.VLF
Why: HF (3–30 MHz) with SSB propagates by sky wave for long range.
Q4. The dominant propagation of NDB (LF/MF) is:
- A.Ground wave✓
- B.Sky wave
- C.Line-of-sight
- D.Satellite
Why: LF/MF travels mainly by the ground (surface) wave.
Q5. An SSR transponder replies on:
- A.1030 MHz
- B.1090 MHz✓
- C.121.5 MHz
- D.75 MHz
Why: Interrogation is 1030 MHz; the reply is 1090 MHz.
Q6. The ILS glide path operates in which band?
- A.VHF
- B.UHF (329–335 MHz)✓
- C.HF
- D.MF
Why: The localizer is VHF; the glide path is UHF (329–335 MHz).
Q7. ILS marker beacons transmit on:
- A.108 MHz
- B.75 MHz✓
- C.329 MHz
- D.1090 MHz
Why: All markers share a 75 MHz carrier, differing in tone/code.
Q8. Moving from 25 kHz to 8.33 kHz channel spacing roughly:
- A.Halves the number of channels
- B.Triples the number of channels✓
- C.Has no effect
- D.Doubles the band width
Why: 8.33 kHz is one-third of 25 kHz, so about three times as many channels fit.
Q9. Aviation VHF communication is:
- A.Horizontally polarized
- B.Vertically polarized✓
- C.Circularly polarized
- D.Unpolarized
Why: Aviation VHF comms are vertically polarized — hence the vertical blade antenna.
Q10. Higher-frequency antennas are physically shorter because:
- A.They use less power
- B.Wavelength shrinks as frequency rises, and antennas are sized to the wavelength✓
- C.They are horizontally polarized
- D.They carry less data
Why: Antennas are a fraction of a wavelength; shorter λ at high f means a shorter aerial.
Q11. The radio altimeter operates in the:
- A.VHF band
- B.HF band
- C.SHF band (≈4200–4400 MHz)✓
- D.LF band
Why: The radio altimeter works around 4200–4400 MHz in the SHF band.
Q12. The maritime distress frequency in the MF band is:
- A.121.5 MHz
- B.2182 kHz✓
- C.406 MHz
- D.243.0 MHz
Why: 2182 kHz is the maritime distress frequency (MF).
Q13. The international VHF emergency frequency and the UHF military one are:
- A.121.5 / 122.5 MHz
- B.121.5 / 243.0 MHz✓
- C.118.0 / 136.975 MHz
- D.406 / 121.5 MHz
Why: 121.5 MHz (VHF guard) and 243.0 MHz (UHF military guard); 243 = 2 × 121.5.
Q14. VOR operates in the:
- A.VHF band (108.0–117.975 MHz)✓
- B.UHF band
- C.HF band
- D.MF band
Why: VOR is VHF, 108.0–117.975 MHz (sharing 108–111.95 with ILS-LOC).
Q15. DME operates in the:
- A.VHF band
- B.UHF band (962–1213 MHz)✓
- C.SHF band
- D.LF band
Why: DME is UHF, 962–1213 MHz.