Thursday, November 05, 2009

What's in a call sign, anyway?

Most people have some familiarity with call signs, if nothing else from broadcast radio stations, which in the US tend to be four letters starting with either K or W.  The more knowledgeable will know that in the broadcast services, K stations are west of the Mississippi and W stations east of it (with some grandfathered exceptions).  Those near the borders may know that Canadian stations start with a C, and Mexican stations with an X.  But, unless you're a shortwave listener or a ham, you probably don't know why the letters used are K and W, or what other letters might be used for, if anything.

The ITU, which I talked about in my last post, is the entity that makes the rules that everyone has to follow for call signs.  Each member country is assigned one or more one or two character prefixes (or, in two cases, three character), and all call issued by that country have to start with one of those prefixes.  There are nine one-character prefixes: B, F, G, I, K, M, N, R, and W; the United States, being a charter member of the ITU and the largest at the time that it was decided to regularize call signs, got three of them; (N, K, and W); the UK gets two (G and M), and the other four go to China (B), France (F),  Italy (I), and Russia (R).  Everyone else has to use at least two characters for national identification; Canada, for example, is allocated CF through CK, and Mexico is allocated XA through XI.  (Both countries have other allocations.)  Some countries even have prefixes that start with digits instead of letters.

So why N, K, and W for the US?  France, Italy, and Russia got their initials, after all.  Well, during the early years the US military used A call signs for Army stations and N call signs for Navy stations.  W (. - -) and K (- . -) are what you get when you add a dah to the Morse code for A (. -) and N (- .), and so commercial stations adopted those letters.  The United States has since given up part of A for the use of other nations, and now only has AA through AL (in addition to all of W, K, and N).

In addition to allocating prefixes to the many member nations, the ITU also sets standards for the parts of the callsign after the prefix, at least in certain services.  For amateur radio stations, the ITU mandates a one or two character national prefix, then a digit, and then up to four additional characters, the last of which must be a letter.  For the United States, which has three one-character prefixes, that means a callsign can be as short as three characters or (in theory) as long as 7.  The FCC, however, does not issue four-character suffixes yet, and reserves the so-called "one-over-one" callsigns (one letter, one digit, and one more letter) as "special event stations" (which are issued for short-term use by any ham who requests and obtains one from the NCVEC, who administers that program, and never permanently), so all FCC-issued amateur call signs are four to six characters long.  Not all combinations within this space are used, either; the FCC excludes for the moment all "two-over-three" (two letters, one digit, and three letters) call signs beginning with A and N from the amateur service, and excludes certain others combinations for a variety of other reasons.  Also, while the ITU regs would allow for the issuance of a call sign containing more than one digit, the FCC does not do this; US amateur call signs always contain exactly one digit.  And that digit is not entirely without meaning.

For the purpose of the amateur radio service, the FCC divides the country into 13 regions.  The first 10 regions, numbered 1 through 9, and 0, are groupings within the "lower 48" (see map to right).  Regions 11 through 13 are Alaska; Puerto Rico and other Caribbean islands; and Hawaii and other Pacific islands.  The FCC issues call signs based on what region the amateur's mailing address is in, and within each region based also on the amateur class of license, using what is called the sequential call sign system.  For those in regions 1 through 10, the digit in the call sign corresponds to the region number; for regions 11, 12, and 13 the digit used also depends on location (typically, which island you're on).  Every amateur gets a sequentially-issued call sign initially; after that a ham's call sign will only change (barring extraordinary events) if the amateur, applies for a vanity call sign or requests a new sequentially-issued call sign.  Also, once the FCC has issued a call sign, it will never issue it again via the sequential system; the only way for a call sign that has been abandoned to be used again is via the vanity call sign system. 

In addition to dividing the country into 13 regions, the call signs available in each region are further divided into four groups, A through D.  Calls in Group A are reserved only to Extras; those in Group B are available to Extras and Advanceds; those in Group C to everyone except Novices; and those in Group D are available to any amateurs.  Because of this, you can tell from a call sign what the minimum license class someone has: someone with a two-over-one or a one-over-two is necessarily an Extra.  But you cannot assume that someone with a two-over-three is a Novice (and in fact that's almost certainly not the case), for three reasons.  First, a ham who upgrades does not automatically get a new call (anymore; that used to be different), and so could have a higher license class than his or her call sign group indicates.  Second, a ham may request any call sign which is permitted to his or her license class through the vanity program.  The third, and perhaps most common, for call signs that don't fully reflect the licensee's operating class is that Group C is exhausted in almost all regions, which means new General and Technician licensees (in the lower 48, at least) now get two-over-three "Novice" calls (as do initial club licenses, which are applied for through Club Station Call Sign Administrators, instead of the usual VE process). 

This post has been brought to you by pool questions T1B03, T1B04, T1B05, T1B06, T1B08, T1B09, and T1B10.