Radio broadcasting refers to using radio waves to send signals to large groups of listeners. Early use of radio focused on using the technology as an alternative to the telegraph, but by the 1920s broadcast radio had taken off as a major telecommunications medium. Today, in addition to traditional AM and FM radio, there is also satellite radio, digital radio broadcasts and radio-style stations available through the internet.
What Is Radio Broadcasting?
Radio broadcasting is any use of radio waves to send messages to large groups of people. Typically radio is used to send audio signals such as talk or music programming. Radio stations broadcast at different frequencies, which are sometimes referred to as wavelengths, since the frequency of a radio wave and its wavelength are mathematically related. To pick up a radio broadcast, you must use a radio tuned to the right frequency.
There are commercial and nonprofit radio broadcasters in the United States and around the world, broadcasting on frequencies reserved for amplitude modulation, or AM, signals and frequency modulation, or FM, signals. FM is more widely used for music because it delivers better sound quality. Modern radio broadcasts include news, talk, sports, religious programming and wide varieties of musical styles. In the past, fictional dramas and comedies were often broadcast on the radio, but these have since largely moved to television and the internet.
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Amateur and CB Radio
In the U.S., the Federal Communications Commission licenses radio broadcasters, and it's illegal to operate without a license. Stations that do so are known as pirate radio stations, and they risk legal trouble. Amateur radio operators, colloquially known as hams, are also licensed by the FCC, or the equivalent authority in other countries, and are allowed to use certain frequencies for amateur, noncommercial broadcasts.
Another set of frequencies are set aside for citizens band, or CB, radio. Anyone may broadcast on CB radio frequencies without a license, and the CB frequencies are sometimes used by long-distance truckers and drivers to communicate about road conditions. Some drivers have since switched to smart phone apps with a similar function.
New Styles of Broadcast Radio
In addition to AM and FM radio, there's also satellite radio, which uses a separate set of frequencies to beam signals from satellites in space to paying subscribers. Many cars come with satellite radio receivers and limited-time subscriptions, helping to boost the service's popularity.
Some broadcasters now broadcast digital radio signals, as well as traditional analog signals. These can deliver higher sound quality and additional information that can be displayed on a radio receiver.
Internet radio stations also exist. Though they're technically not using radio waves to reach listeners, they're often using similar formats to broadcast music, talk or sports. Radio also sees online competition from podcasts, which offer prerecorded programs that you can download or stream to listen to at your convenience.