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Broadcasting is the distribution of sound and audiovisual content to dispersed audiences via an electronic mass communications medium, typically using the electromagnetic spectrum (), in a one-to-many model. (1999). 9780226662770, University of Chicago Press. ISBN 9780226662770 Broadcasting began with AM radio, which became popular around 1920 with the spread of vacuum tube radio transmitters and radio receiver. Before this, most implementations of electronic communication (early radio, telephone, and telegraph) were , with the message intended for a single recipient. The term broadcasting evolved from its use as the agricultural method of sowing seeds in a field by casting them broadly about. It was later adopted for describing the widespread distribution of information by printed materials (1877). 9785870894072, R.E. Strahorn. ISBN 9785870894072 or by telegraph. "Medical Advertising" , Saint Louis Medical and Surgical Journal, December 1886, p. 334: "operations formerly described in the city press alone, are now sent broadcast through the country by multiple telegraph". Examples applying it to "one-to-many" radio transmissions of an individual station to multiple listeners appeared as early as 1898. "Wireless Telegraphy" , The Electrician (London), 14 October 1898, p. 815: "there are rare cases where, as Dr. Lodge once expressed it, it might be advantageous to 'shout' the message, spreading it broadcast to receivers in all directions".
Over-the-air broadcasting is usually associated with radio and television, though more recently, both radio and television transmissions have begun to be distributed by cable (cable television). The receiving parties may include the general public or a relatively small subset; the point is that anyone with the appropriate receiving technology and equipment (e.g., a radio or television set) can receive the signal. The field of broadcasting includes both government-managed services such as public radio, community radio and public television, and private commercial radio and commercial television. The U.S. Code of Federal Regulations, title 47, part 97 defines broadcasting as "transmissions intended for reception by the general public, either direct or relayed".Electronic Code of Federal Regulation. (28 September 2017). Retrieved 2 October 2017. Private or two-way telecommunications transmissions do not qualify under this definition. For example, amateur radio ("ham") and citizens band (CB) radio operators are not allowed to broadcast. As defined, transmitting and broadcasting are not the same.
Transmission of radio and television programs from a radio or television station to home receivers by is referred to as over the air (OTA) or terrestrial broadcasting and in most countries requires a broadcasting license. Transmissions using a wire or cable, like cable television (which also retransmits OTA stations with their consent), are also considered broadcasts but do not necessarily require a license (though in some countries, a license is required). In the 2000s, transmissions of television and radio programs via streaming digital technology have increasingly been referred to as broadcasting as well.
World War I accelerated the development of radio for military communications. After the war, commercial radio AM broadcasting began in the 1920s and became an important mass medium for entertainment and news. World War II again accelerated the development of radio for the wartime purposes of aircraft and land communication, radio navigation, and radar. Development of stereo FM broadcasting of radio began in the 1930s in the United States and the 1970s in the United Kingdom, displacing AM as the dominant commercial standard. (2025). 9781623566654, Bloomsbury Publishing. ISBN 9781623566654
On 25 March 1925, John Logie Baird demonstrated the transmission of moving pictures at the London department store Selfridges. Baird's device relied upon the Nipkow disk and thus became known as the mechanical television. It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning on 30 September 1929. However, for most of the 20th century, televisions depended on the cathode-ray tube invented by Karl Braun. The first version of such a television to show promise was produced by Philo Farnsworth and demonstrated to his family on 7 September 1927. After World War II, interrupted experiments resumed and television became an important home entertainment broadcast medium, using VHF and UHF spectrum. Satellite broadcasting was initiated in the 1960s and moved into general industry usage in the 1970s, with DBS (Direct Broadcast Satellites) emerging in the 1980s.
Originally, all broadcasting was composed of using analog transmission techniques but in the 2000s, broadcasters switched to digital signals using digital transmission. An analog signal is any continuous signal representing some other quantity, i.e., analogous to another quantity. For example, in an analog audio signal, the instantaneous signal voltage varies continuously with the Sound pressure. In contrast, a digital signal represents the original time-varying quantity as a sampled sequence of quantized values which imposes some bandwidth and dynamic range constraints on the representation. In general usage, broadcasting most frequently refers to the transmission of information and entertainment programming from various sources to the general public:
The world's technological capacity to receive information through one-way broadcast networks more than quadrupled during the two decades from 1986 to 2007, from 432 exabytes of (optimally compressed) information, to 1.9 zettabytes. This is the information equivalent of 55 newspapers per person per day in 1986, and 175 newspapers per person per day by 2007.
Historically, there have been several methods used for broadcasting electronic media audio and video to the general public:
Broadcasters may rely on a combination of these . For example, in the United States, National Public Radio (NPR) and the Public Broadcasting Service (PBS, television) supplement public membership subscriptions and grants with funding from the Corporation for Public Broadcasting (CPB), which is allocated bi-annually by Congress. US public broadcasting corporate and charitable grants are generally given in consideration of underwriting spots which differ from commercial advertisements in that they are governed by specific FCC restrictions, which prohibit the advocacy of a product or a "call to action".
A disadvantage of recording first is that the public may learn the outcome of an event before the recording is broadcast, which may be a spoiler. Prerecording may be used to prevent from deviating from an officially approved screenplay during a live radio broadcast, as occurred with propaganda broadcasts from Germany in the 1940s and with Radio Moscow in the 1980s. Many events are advertised as being live, although they are often recorded live (sometimes called "live television-to-video tape"). This is particularly true of performances of musical artists on radio when they visit for an in-studio concert performance. Similar situations have occurred in television production (" The Cosby Show is recorded in front of a live television studio audience") and news broadcasting.
A broadcast may be distributed through several physical means. If coming directly from the radio studio at a single station or television station, it is sent through the studio/transmitter link to the transmitter and hence from the television antenna located on the radio masts and towers out to the world. Programming may also come through a communications satellite, played either live or recorded for later transmission. Networks of stations may simulcast the same programming at the same time, originally via microwave link, now usually by satellite. Distribution to stations or networks may also be through physical media, such as magnetic tape, compact disc (CD), DVD, and sometimes other formats. Usually these are included in another broadcast, such as when electronic news gathering (ENG) returns a story to the station for inclusion on a .
The final leg of broadcast distribution is how the signal gets to the listener or viewer. It may come over the air as with a radio station or television station to an antenna and radio receiver, or may come through cable television or cable radio (or wireless cable) via the station or directly from a network. The Internet may also bring either internet radio or streaming media television to the recipient, especially with allowing the signal and bandwidth to be shared. The term broadcast network is often used to distinguish networks that broadcast over-the-air television signals that can be received using a tuner inside a television set with a television antenna from so-called networks that are broadcast only via cable television (cablecast) or satellite television that uses a dish antenna. The term broadcast television can refer to the television programs of such networks.
Broadcasting focuses on getting a message out and it is up to the general public to do what they wish with it. Peters also states that broadcasting is used to address an open-ended destination. There are many forms of broadcasting, but they all aim to distribute a signal that will reach the target audience. Broadcasters typically arrange audiences into entire assemblies. In terms of media broadcasting, a radio show can gather a large number of followers who tune in every day to specifically listen to that specific disc jockey. The disc jockey follows the script for their radio show and just talks into the microphone. They do not expect immediate feedback from any listeners. The message is broadcast across airwaves throughout the community, but the listeners cannot always respond immediately, especially since many radio shows are recorded prior to the actual air time. Conversely, receivers can select opt-in or opt-out of getting broadcast messages using an Excel file, offering them control over the information they receive.
Broadcast engineering involves both the studio and transmitter aspects (the entire airchain), as well as . Every station has a broadcast engineer, though one may now serve an entire station group in a city. In small the engineer may work on a contract basis for one or more stations as needed.
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