Since the beginning of radio broadcasting in the 1920s, U.S. radio and TV broadcast stations have had to announce their call signs and communities of licence at reqular intervals. Originally it was required every 15 minutes, then each half hour, finally, since around the early 1980s, once-an-hour on the hour. This was more important in the early years, because radio stations had trouble staying on frequency. But even today it can be helpful in tracking down transmitter problems, as a spurious signal might be heard up to hundreds of kilometers away, on a frequency far removed from the station’s normal one. The United States is one of the few countries which still requires that broadcast stations announce their call signs. Most other countries, even if they bother to assign call signs to their broadcasting stations, allow them to identify themselves through slogans or network IDs, which often are officially registered.
The main requirement for the hourly “legal ID”, as it is usually known, is that it consist of the station’s call sign followed by its community of licence. It is supposed to be transmitted “hourly, as close to the hour as feasible, at a natural break in program offerings. Television broadcast stations may make these announcements visually or aurally.” (For a fuller review of the standards, see: Legal Identification.) Informally, “near the hour” has usually been interpreted as +/- five minutes, although many stations are a lot more lax than that.
The Federal Communications Commission has traditionally tried to distribute radio and TV station licences to as many communities as possible. So, one of the reasons for keeping the legal ID announcements is that, at least once an hour, the station tells its audience where it is located, presumably strenghening its ties to that community. One problem is that most suburban radio and TV stations want you to think they are actually located in “the big city”. Thus, the station that begged and pleaded with the FCC for the privilege to own “Podunk’s own radio station”, immediately goes to great lengths to give everyone the impression that the station is actually licenced to nearby “Metropolis”. (Stations used to have to have local studios and provide local program services to their communities of licence, but these requirements have been almost completely eliminated in the last decade. In some cases it is now quite possible for announcers to never actually set foot in their station’s community of licence).
Also, some stations have found that “all the good call signs are taken”, and they couldn’t get the call sign they really wanted. The FCC allows stations to use slogans–which can look like call signs–and also mention additional cities as many times as they wish. So, for example, WPBG, licenced to Podunk, can proclaim itself to be WBIG Metropolis hundreds of times per hour, even at the top of the hour, as long as once an hour they utter their legal ID of “WPBG Podunk”.
Stations often go to great lengths to make it as hard as possible for you to determine what their actual call and station location is. For radio stations, the most common trick is to run about 10 commercials in a row at about 10 minutes before the hour, quietly inserting a quick, <font size="-1" color=gray>“wpbg podunk”</font> between, say, commercials 6 and 7. (I’ve also heard cases where loud sound effects, odd cadences, and audio clipping make the legal ID virtually impossible to understand, even if you are listening for it.) Then, at the top of the hour, the station announces with appropriate fanfare to its audience that they are listening to The mighty WBIG METROPOLIS, and although this may sound like the legal ID, in this case WBIG technically is the station’s slogan, and Metropolis a town that they are fond of.
I once saw a post in rec.radio.broadcasting which said that one station had used the following type of announcement at the top of the hour to hide their actual community of licence: “You’re listening to WZZZ Metropolis. If you see news happening, call our news desk at 555-WZZZ, Podunk listeners, call 555-1234”. In the preceding, the very-easy-to-miss legal ID was WZZZ, Podunk. Also, there is a local TV station which has a horizonally-scrolling visual graphic, so that embeded in the following: “RALEIGH DURHAM FAYETTEVILE WNCN GOLDSBORO RALEIGH DURHAM etc.” is the legal ID of “WNCN Goldsboro”. Other TV stations use font sizes that can be seen only on jumbo screens, or display the ID in a corner of the picture when they think no one is watching.
The station ID requirements are rarely enforced by the FCC. Often, only if a station is in trouble for some other reason will FCC fine them for not complying with the regulations.
Side note: It’s Napoleon XIV.
