Call sign

From Freepedia

In broadcasting and radio communication, a call sign (also known as a callsign or call letters, or abbreviated as a call) are a unique designation for a transmitting station. They can be formally assigned by a government agency, informally adopted by individuals or organizations, or even cryptographically encoded to disguise a station's identity.

Contents

International series

Main article: International Callsign Allocations

International call signs are formal, semi-permanent, and issued by a nation's telecommunications agency. They are used for amateur, broadcast, commercial, maritime and sometimes military radio use (including television in some countries).

Each country has a set of alphabetic or numeric International Telecommunication Union-designated prefixes with which their call signs must begin. For example:

  • The United States uses the prefixes: W, K, N, and AAA to ALZ (only W and K are used for broadcast stations).
  • Canada uses the prefixes: CF-CK, CY-CZ, VA-VG, VO, VX-VY, XJ-XO
  • Mexico uses XA-XI
  • The United Kingdom uses the prefixes: G, M, and 2
  • France uses the prefixes: F, TM
  • Germany uses the prefixes: DA-DR
  • Chad uses the prefix: TT
  • Italy uses the prefix: I

Aircraft

In nearly all jurisdictions, every licensed aircraft is assigned a unique registration or tail number. Registrations for civil (non-military) aircraft begin with one or more code letters to denote the country of origin. For example, the registrations of U.S. civilian aircraft begin with the letter N followed by some numerical digits and/or alphabetic letters according to the following standards:

  • U.S. registration numbers may not exceed five (5) characters in addition to the standard U.S. registration prefix letter "N".
  • These characters may be one (1) to five (5) numbers (eg., N12345), one (1) to four (4) numbers and one (1) suffix letter (e.g., N1234Z), or one (1) to three (3) numbers and two (2) suffix letters (N123AZ).
  • To avoid confusion with the numbers one and zero, the alphabetic letters "I" and "O" may not be used.
  • An N-Number may not begin with zero. The first zero in a number must be preceded by at least one of the numbers one (1) through nine (9). For example, N01Z is not valid.

Many general aviation aircraft use this registration as their radio call sign, however scheduled airline flights generally use an airline call sign or airline code, followed by the flight number, e.g. United for United Airlines.

Glider pilots often use a supplementary number (the competition number) as their call signs.

Air traffic control facilities are usually identified by location and function, e.g. Boston Center.

Merchant vessels

Merchant vessels are assigned a call sign by their national licensing authority. In the case of states such as Liberia or Panama, which are flags of convenience for ship registration, call signs for larger vessels consist of the national prefix plus three letters (for example, 3LXYZ). United States vessels are given call signs beginning with W.

Amateur radio

Amateur radio call signs are in the international series and normally consist of a one- or two-character prefix, a number (which sometimes corresponds to a geographic area within the country) and a 1, 2, or 3 character suffix. The number following the prefix is normally a single number (0 to 9). Some prefixes, such as Djibouti's (J2), consist of a letter followed by a number. Hence, in the hypothetical Djibouti call sign, J29DBA, the prefix is J2, the number is 9, and the suffix is DBA.

The numbers are sometimes assigned geographically. In the Italian call sign, IK1TZO, IK is the prefix, the number component is 1 and corresponds to the Piedmont region, and TZO is the suffix. Another example is WB3EBO. WB is the prefix, the number 3 most often indicates that the station is located in Delaware, Maryland, Pennsylvania, or the District of Columbia. The suffix is EBO. For the district numbers within the United States, see ARRL map.

Broadcast call signs

North America

Main article: North American call sign

Broadcast stations in North America generally use call letters in the international series. There are some common conventions followed in each country. In Canada, call signs begin with the letter C, except for four stations in St. John's which begin with the letters VO; three of these predate Newfoundland's union with Canada in 1949, and the fourth was given special permission to adopt the callsign in 1981 because of its ownership association with one of the pre-1949 stations. Mexican call signs begin with an XE for medium-wave radio stations and XH in other cases. In the United States, the first letter is K for stations west of the Mississippi River and W for those east of the Mississippi. There are a few exceptions-mostly with stations assigned call signs before the Federal Communications Commission devised the east/west split.

Australia

In Australia, broadcast call signs begin with a single-digit number indicating the state or territory, followed by two letters for AM stations and three for FM. Some AM stations retain their old call signs when moving to FM, or just add an extra letter to the end. Australian broadcast stations originally used the prefix VL-, but since Australia has no nearby neighbors, this practice was soon discarded in use.

Television station call signs begin with two letters usually denoting the station itself, followed by a third letter denoting the state. For example, NBN's call sign stands for Newcastle Broadcasting, New South Wales. There are some exceptions:

  • ABC television stations outside of state capitals add a fourth letter between AB and the state. This is used to denote the area e.g. the Newcastle station is known as ABHN, standing for Australian Broadcasting Corporation, Hunter Valley, New South Wales. State capital stations follow the same rule as commercial stations.
  • SBS television stations all use SBS in their call signs, regardless of the state.
  • Commercial station Imparja Television uses IMP, even though they are based in Alice Springs in the Northern Territory.

Letters and numbers used by Australian stations:

Europe/Asia

In Europe and much of Asia, call signs are normally not used for broadcast stations. Japan, South Korea and Taiwan are exceptions to this general rule. Other countries have yet other formats for assigning call signs to domestic services.

Military call signs

In wartime, monitoring an adversaries communications can be a valuable form of intelligence. Consistent call signs can aid in this monitoring, so in wartime, military units often employ tactical call signs and sometime change them at regular intervals. In peacetime, some military stations will use fixed call signs in the international series.

US Army

The United States Army uses fixed call signs which begin with W, such as WAR, used by U.S. Army Headquarters.

US Air Force

Fixed call signs for the United States Air Force stations begin with A, such as AIR, used by USAF Headquarters. The USAF also uses semi-fixed identifiers consisting of a name followed by a two or three digit number. The name is assigned to a unit on a semi-permanent basis; they change only when the U.S. Department of Defense goes to DEFCON 3. For example, JAMBO 51 would be assigned to a particular B-52 aircrew of the 5th Bomb Wing, while NODAK 1 would be an F-16 fighter with the North Dakota Air National Guard. The most recognizable call sign of this type is Air Force One, used when any Air Force aircraft is transporting the U.S. President. Individual military pilot or other flight officer usually adopt a personal aviator call sign.

US Navy/Coast Guard

The United States Navy and United States Coast Guard use a mixture of tactical call signs and international call signs beginning with the letter N. For example, the carrier USS John F. Kennedy has the call sign NJFK.

Transmitters requiring no call signs

No call signs are issued to transmitters of long-range navigation systems (LORAN-C, Decca, Alpha, Omega) and transmitters on frequencies below 10 kHz, because frequencies below 10 kHz are not subject to international regulations. In addition, in some countries low-power personal and broadcast radio (Citizen's Band, Part 15, and the like) is allowed; a call sign is not always required for such stations, though especially on personal radio services it is considered a matter of etiquette to create one's own.

See also

External links

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