From the earliest days of radio, broadcasting has had its origins in the United States. In 1906, the first experimental stations were sending music over the radio waves to ships at sea. In 1912, the United States started to license experimental broadcast stations.
Unlike many other countries, broadcasting within the U.S. has been operated exclusively by private organizations. There is no equivalent to the BBC in the United States. The Public Broadcasting System and the Corporation for Public Broadcasting do provide some programming, but they provide it on a contract, purchased basis to educational television (and radio) stations, most of which are either privately owned by local non-profits or by the school board of a community.
The rest of all broadcasting is done by private companies who all but have an ownership of the channel they operate on, even though the fiction of holding a hearing for a license renewal is done by the FCC every few years. Recent changes have increased the number of broadcast stations one entity may own, thus allowing very large companies like iHeartMedia to own hundreds of stations that reach something like 20% of the entire country. Back when the national networks had considerable more reach, they were each limited to no more than seven broadcast stations of their own.
In the 1920s, the United States switched to its current pattern of station call signs.
Call signsCall signs are codes that identify a station. The United States is allocated the prefixes AA-AL, K, N and W. For broadcasting, only K and W are used, derived from the Morse code symbols for A and N, with an extra dash. Except for the oldest stations and translators, all broadcast stations are four letters long. Older stations may have three letter callsigns left over from earlier days, such as San Francisco's KGO or Chicago's WGN.
K is used for stations west of the Mississippi River, and W is used for stations east of the Mississippi. Prior to 1923, the dividing line was further west note . Because of this rule change, and other more complicated reasons, there are stations that do not follow the K/W convention. KDKA-AM in Pittsburgh, the oldest commercial station in the United States note , and WOAI-AM in San Antonio, the station farthest west in the continental US with a W, are two notable examples. In Minnesota and Louisiana, where the Mississippi River begins and endsand which, more to the point, have significant territory on both sides of the riverstations can have either W or K.
There are also exceptions based upon prior ownership. In the Dallas-Fort Worth area, every television station's call sign starts with a K except for WFAA, because the station was originally owned by the same company that owned WFAA-AM, so it was allowed to keep its W call sign. This practice of allowing call sign carry over continues even today. Stations with a common owner can have the same callsign, but with a different suffix. So there can be a KOPB-AM, a KOPB-FM and a KOPB-DT (for digital television). Other suffixes are "TV" for analog television and "LP" for low power (there's also "CA", "CD", and "LD"). To reach communities outside of the main transmitter's area, translators are used. They have names like K11BX (the number in the middle is the "channel" or frequency assignment where the station operates), and are lower power. The number will also tell you the type of translator: if the number is two digits, it's a repeater of a television station; a three digit number is a repeater of an FM station (the FM repeater number itself identifies the FCC channel, which is only used by the FCC; 87.9 is Channel 200, while 107.9 is Channel 300); for instance, W 241 AG would identify a station at 96.1 FM, as it's on FM Channel 241). Often, religious broadcasters abuse the translator rules and have FM translators scattered across the country.
Stations are commonly identified by their callsigns, which can be a big part of the station's branding.
BandsThere are five main broadcast bands in the United States:
- Amplitude modulation, or AM, radio covers 520 to 1710 kHz. This band is mostly used for news, talk and sports radio (a shift from once-commonplace music formats which began in the late '80s). Its advantages are long range and simple receivers. It has low bandwidth, so most music stations have moved to the FM band. Also known as medium wave.
- Frequency modulation, or FM, radio covers 87.9 to 107.9 MHz (87.7 FM, where the audio for analog channel 6 is heard, is also on many radios, with some low-power stations taking advantage of that to air a radio format). The last digit after the decimal point is always an odd number. It is used for all kinds of broadcasts, from college radio to top 40 music. HD radio is starting here as a subcarrier, although the receivers are really expensive now. FM is good for stereo music and can support data streams on subcarriers. Part of the VHF band. News, talk and sports radio are making their ways to FM, slowly but surely.
- VHF TV covers channels 2 to 13. There is no Channel 1.note Starting in February 2009 analog television stations switched to digital stations, and all stations switched by June.
- UHF TV covers channels 14 to 52. Channels above 52 have been allocated to other services, and channel 37 is reserved for radio astronomy.
- Shortwave radio is mostly unused for broadcasting in the United States. What stations do exist are religious (often run by a new "prophet") or operated by fringe groups. You can find official time signal broadcasts there too, among other signals; really cool alarm and digital clocks note can set themselves to these signals.
Standards and RegulationThe Media Watchdog in the United States is the Federal Communications Commission. Besides being notorious for "broadcast standards and practices", the FCC sets the rules for channels, power, and other technical stuff, as well as licensing stations.
The United States used NTSC for analog television broadcasting and now ATSC for digital television. HD Radio is the digital radio standard, despite the rest of the world using the DAB standard
NetworksThere is no national government-operated broadcaster. All stations are funded by advertising, donations or money from
Public television and radio is partially funded by the government through the CPB, but isn't a government broadcaster, though individual stations may be operated by local governments. PBS is the public television network and NPR is one of the public radio networks.