Science Fair Project Encyclopedia
In broadcasting, a callsign or call sign (also call letters) is 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.
International callsigns 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, as well as for broadcast television.
- 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 X
- 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
See main article: International Callsign Allocations
Each licensed aircraft is assigned a unique tail number. Tail numbers for non-military aircraft are also in the international call sign series and can be used as a radio call sign. For example, U.S. registered civilian aircraft are assigned a tail number consisting of the letter N followed by some digits and/or 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 (ex. - N1234Z), or one (1) to three (3) numbers and two (2) suffix letters (N123AZ).
- To avoid confusion with the numbers one and zero, the 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.
Air traffic control facilities usually identify by location and function, e.g. Boston tower. Scheduled airline flights generally do not use their tail numbers for identification; instead they use an airline code, such as United for United Airlines, followed by the flight number. See main article: airline call sign.
Amateur radio callsigns 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 callsign, J29DBA, the prefix is J2, the number is 9, and the suffix is DBA.
The numbers are sometimes assigned geographically. In the Italian callsign, IK1TZO, IK is the prefix, the number component is 1 and corresponds to the Piemonte 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.
In Australia, broadcast callsigns 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 callsigns 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 callsigns begin with two letters usually denoting the station itself, followed by a third letter denoting the state. For example, NBN's callsign 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 commerical stations.
- SBS television stations all use SBS in their callsigns, 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:
In Europe and much of Asia, callsigns 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 callsigns to domestic services.
In wartime, monitoring an adversaries communications can be a valuable form of intellegence. Consistant call signs can aid in this monitoring, so in wartime, military units often employ tactical callsigns and sometime change them at regular intervals. In peacetime, some military stations will use fixed call signs in the international series.
US Air Force
Fixed callsigns 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 callsign of this type is Air Force One, used when any plane is carrying the U.S. President, or Marine One, used to identify any helicopter doing the same thing. Individaul 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 callsigns and international callsigns beginning with the letter N. For example, the carrier USS John F. Kennedy has the callsign NJFK.
- Airline call sign
- Aviator call sign
- Cosmonaut call sign
- International Callsign Allocations
- Maritime Mobile Service Identity
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