GMDSS GMDSS Frequencies and Radio Bands 2 — Questions and Answers
Question 1: What is the HF DSC distress frequency in the 8 MHz band?
- 8291 kHz
- 8414.5 kHz (Correct answer)
- 8376 kHz
- 8195 kHz
Correct answer: 8414.5 kHz
8414.5 kHz is the designated HF DSC distress frequency in the 8 MHz band used for long-range GMDSS alerting.
Question 2: Navtex broadcasts on 490 kHz are primarily used for what purpose?
- International English broadcasts
- Local language maritime safety broadcasts (Correct answer)
- DSC alerting only
- Satellite uplink communications
Correct answer: Local language maritime safety broadcasts
490 kHz Navtex broadcasts are used for local or national language maritime safety information, complementing the international 518 kHz service.
Question 3: What is the frequency of the satellite EPIRB signal transmitted on the Cospas-Sarsat system?
- 121.5 MHz only
- 406 MHz (Correct answer)
- 243 MHz
- 156.8 MHz
Correct answer: 406 MHz
406 MHz is the primary frequency used by Cospas-Sarsat EPIRBs for satellite detection and accurate position reporting.
Question 4: Which frequency do Search and Rescue Transponders (SARTs) operate on?
- 9 GHz (X-band radar) (Correct answer)
- 3 GHz (S-band radar)
- 156.8 MHz
- 406 MHz
Correct answer: 9 GHz (X-band radar)
SARTs operate on 9 GHz (X-band) radar frequency, responding to radar pulses from ships and aircraft to show a series of blips on radar displays.
Question 5: What is the homing frequency transmitted by an EPIRB to assist SAR aircraft and vessels?
- 406 MHz
- 121.5 MHz (Correct answer)
- 243 MHz
- 2182 kHz
Correct answer: 121.5 MHz
EPIRBs transmit a homing signal on 121.5 MHz in addition to the 406 MHz satellite signal to help SAR units home in on the beacon.
Question 6: Which frequency range is used by AIS (Automatic Identification System) transmissions?
- VHF channels 87B and 88B (161.975/162.025 MHz) (Correct answer)
- MF 2182 kHz
- HF 8 MHz band
- UHF 406 MHz
Correct answer: VHF channels 87B and 88B (161.975/162.025 MHz)
AIS uses VHF channels 87B (161.975 MHz) and 88B (162.025 MHz) for automatic vessel identification and position reporting.
GMDSS GMDSS Frequencies and Radio Bands 2
What is the HF DSC distress frequency in the 8 MHz band?