Regular Hackaday readers will be familiar with our convention of putting the name, nickname, or handle of a person in square brackets. We do this to avoid ambiguity as sometimes names and particularly nicknames can take unfamiliar forms that might be confused with other entities referred to in the text. So for example you might see them around [Bart Simpson], or [El Barto]. and occasionally within those brackets you’ll also see a capitalised string of letters and numbers after a name. For example the electronic music pioneer [Bob Moog, K2AMH], which most of you will recognise as an amateur radio callsign.
Every licenced radio amateur is issued one by their country’s radio authority as a unique identifier, think of it as similar to a car licence plate. From within the amateur radio bubble those letters and numbers can convey a significant amount of information about where in the world its user is located, when they received their licence, and even what type of licence they hold, but to outsiders they remain a mysterious and seemingly random string. We’ll now attempt to shed some light on that information, so you too can look at a callsign in a Hackaday piece or anywhere else and have some idea as to its meaning.
Happily for the would-be callsign spotter, there is an internationally agreed format for amateur radio callsigns. It does have occasional edge cases and exceptions, but the chances of encountering them is slim. There will always be a prefix of up to three alphanumeric characters which identifies a country or territory, followed by a single digit, and then followed by up to four characters.
Returning to [Bob Moog]’s callsign [K2AMH] above as a straightforward example, the “K” is one of the prefix letters A, N, K, and W so far used in the ranges assigned to the USA, the “2” indicates that the callsign was issued in New York or New Jersey because the digit in a US callsign represents a region, and the “AMH” is a sequentially issued string of letters acting as a personal identifier. In more recently issued callsigns this will often be a vanity string, perhaps the operator’s initials or similar.
A seasoned callsign-spotter would also be able to tell you that [Bob Moog]’s callsign originates from sometime in the 1950s, as that was the period in which they started issuing single-letter “K” callsigns, and that it denotes a full or advanced class licence because the “K” is not accompanied by another letter. The FCC provide a handy guide to the callsigns they currently issue, if you are curious.
[Bob Moog] provides us with our straightforward example above, but as is so often the case there are many exceptions and international differences that mean not all callsign components have the same interpretation. For example in British callsigns the number does not represent a region, instead for the vast majority it conveys the age of the callsign and the class of licence for which it was issued. If you are digging that deep into the information contained within a callsign issued in another territory, you will often have to resort to your favourite search engine.
Sometimes you will see extra letters with a slash at the start and end of a callsign. Letters at the start mean that the station is operating in another country or territory, for example. Reciprocal agreements exist between countries allowing foreign amateurs to operate within their borders, when doing so they prepend the appropriate international prefix to their own callsign with a slash to indicate the true location of their station. Our example in the image to the left shows a Canadian station working this way in Kuwait.
Of course, not all radio amateurs work from home. There is a long tradition of portable operation, in cars, on foot, in boats, and even in the air. When operating in this manner there is a requirement to indicate this by adding a slash and an appropriate suffix on the end of the callsign. Thus you’ll see “/P” for portable or on foot, “/M” for mobile, and even occasionally “/MM” for maritime mobile and “/AM” for aeronautical mobile. There are tales for example of people working [King Hussein] of Jordan as [JY1/AM] from his royal jet somewhere over the Atlantic on the way to the USA. Incidentally that Jordanian callsign is one of those rare edge cases we mentioned earlier, it has no letters following its number. When you are king, the ultimate in vanity callsigns can be yours!
There is sometimes an undesirable side to being able to extract so much information from a callsign. People will always find an excuse to impose a hierarchy on any group, and radio amateurs are no exception. Thus you will sometimes find holders of older or more advanced licences excluding or being unpleasant to people whose callsigns they deem to be inferior to their own. We recently heard an oldtimer whose callsign reveals he was probably first licenced in the 1950s or 1960s rip into a recently licenced novice with a British M6 callsign, and it was not a particularly pleasant experience. We’re sure Hackaday readers will agree that it doesn’t matter when you were first licenced or what level of radio examination you have passed. You are only as good as the last piece of radio equipment you built, and the last station you worked with it.
We hope this has given you an insight into amateur radio callsigns, and they no longer appear to you as simply random strings when we feature them. If you are interested in amateur radio, you might like to see a previous feature we did on some of the steps required to take your licence exam.
Callsign plate header image: Cody gg 88 [CC BY-SA 4.0], via Wikimedia Commons.