2182 kHz

The radio frequency of 2182 kHz (kilohertz) is the international calling and distress frequency for maritime radiotelephone communications on the marine MF bands.^[1]

Transmission modes

Transmissions on 2182 kHz commonly use single-sideband modulation (SSB) (upper sideband only), however Amplitude modulation (AM) and some variants such as vestigial sideband are still in use, mainly by vessels with older equipment and by some coastal stations in an attempt to ensure compatibility with older and less sophisticated receivers.

Range

2182 kHz is analogous to Channel 16 on the marine VHF band, but unlike VHF which is limited to about 50 nautical miles (90 km) range, communications on 2182 kHz and nearby frequencies have a typical range of around 150 nautical miles (280 km) during the day and 500 (or more) nautical miles at night[1]. At night a well equipped station can achieve intra-continental communication, but this range can be severely limited in summer because of static caused by lightning.

Silence period

Ship's radio room clock

Twice each hour, all stations using 2182 and 500 kHz were required to maintain a strictly enforced three-minute silence and listening period, starting at h+00, h+30 and h+15, h+45. This allowed any station with distress, urgent or safety traffic the best chance of being heard at that time, even if they were at some distance from other stations operating on reduced battery power, or perhaps reduced antenna efficiency, as for example in a dismasted vessel. As a visual aide-memoire a typical clock in a ship's radio room would have these silence periods marked by shading the sectors between h+00 to h+03 and h+30 to h+33 in green. Similar sectors were marked in red for what used to be the corresponding silence and listening period on 500 kHz. These silence periods are no longer required as the introduction of GMDSS has produced alternative automatic watchkeeping systems.

Licensing

In order to operate a marine radio transceiver on 2182 kHz, the operator must hold a GMDSS General Operating Certificate for mandatory installations or a Long Range Certificate for voluntary ones. Both certificates have a wider syllabus than that of the GMDSS Restricted Operators Course or the RYA Short Range Certificate that is necessary for Marine VHF use. These certificates are also dependent on the vessel whether the radio is a mandatory installation (ROC) or a voluntary one as with leisure craft (SRC) In either case, though, an unqualified operator would not be prosecuted for the use of either rig in what turns out to be a genuine distress situation.

Related distress frequencies

2182 kHz forms an essential part of the Global Maritime Distress Safety System (GMDSS). It has an associated DSC frequency at 2187.5 kHz. Other international distress frequencies, in use as of 2008, include:

• 121.5 MHz as the civil, and 243 MHz as the military aircraft emergency frequencies

• Marine VHF radio Channel 16, (156.8 MHz) for short range maritime use

• 406.025 MHz used by the Cospas-Sarsat international satellite-based search and rescue (SAR) distress alert detection and information distribution system

The U.S. Coast Guard only monitors distress alert signals broadcast using digital 406 MHz emergency position indicating radio beacons as of Feb. 1, 2009. Satellite processing from all 121.5 or 243 MHz locators was discontinued. Digital 406 MHz models became the only ones approved for use in both commercial and recreational watercraft worldwide on Jan. 1, 2007, the Coast Guard said.^[2]

See also

• Distress signal
• Marine VHF radio
• Mayday (distress signal)
• Pan-pan
• Securite
• Global Maritime Distress Safety System
• 500 kHz

References

1. ^ http://www.jproc.ca/rrp/distress.html Distress Communications, RADIO COMMUNICATIONS AND SIGNALS INTELLIGENCE IN THE CANADIAN NAVY
2. ^ http://www.piersystem.com/go/doc/780/248571/ United States Coast Guard, Press Release

External links

• International Telecommunication Union
• Maritime and Coastguard Agency
• Merchant Shipping Regulations
• Example of a Radio Room Clock