2182 kHz
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The radio frequency of 2182 kilohertz (kHz) is the international calling and distress frequency for voice maritime communication (radiotelephony) on the marine MF bands. It is analogous to Channel 16 on the marine VHF band.
Modulation
Transmissions on 2182 kHz should use single-sideband modulation (SSB) (upper sideband only). That said, Amplitude modulation (AM), and some variants in between the two, such as vestigial sideband, are still in use. These are used mainly by vessels with older equipment installed and by some coastal stations in an attempt to ensure compatibility with older and less sophisticated receivers afloat.
GMDSS
2182 kHz forms an essential part of the Global Maritime Distress Safety System (GMDSS). It has an associated DSC frequency at 2187.5 kHz.
Range
Unlike Marine 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.
There are many other marine frequencies, including distress and calling frequencies, in the Marine HF bands, up to and including worldwide coverage with the right conditions. In addition to these, satellite technology can provide worldwide communications for vessels at sea.
Silence Period
Twice each hour, all stations listening on 2182 kHz are required to maintain a strictly enforced three-minute silence period, starting at h+00 and h+30. 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 at h+15 and h+45 may be marked in red for a corresponding silence period on 500 kHz, although this is no longer an active marine distress or listening frequency.
Licencing
In order to operate a marine radio transceiver on 2182 kHz, the operator must hold a GMDSS Long Range Certificate, which requires success on a wider syllabus than that of the GMDSS Short Range Certificate that is necessary for Marine VHF use. 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. (In the United States comparable certificates would be the GMDSS Operator and the GMDSS Restricted Operator licenses.)
See also
- Marine VHF radio
- Mayday (distress signal)
- Pan-pan
- Securite
- Global Maritime Distress Safety System
- 500 kHz
External links
- International Telecommunication Union
- Marine and Coastguard Agency
- Merchant Shipping Regulations
- Example of a Radio Room Clock
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .

