Broadcast signal

"Broadcast" redirects here. For other uses, see Broadcast (disambiguation).


Broadcasting is the distribution of audio and video content to a dispersed audience via any audio or visual mass communications medium, but usually one using electromagnetic radiation (radio waves). The receiving parties may include the general public or a relatively large subset thereof. Broadcasting has been used for purposes of private recreation, non-commercial exchange of messages, experimentation, self-training, and emergency communication such as amateur (ham) radio and amateur television (ATV) in addition to commercial purposes like popular radio or TV stations with advertisements.

History

The term broadcast was first adopted by early radio engineers from the Midwestern United States,[1] treating broadcast sowing as a metaphor for the dispersal inherent in omnidirectional radio signals.Broadcasting is a very large and significant segment[quantify] of the mass media.

Originally all broadcasting was composed of analog signals using analog transmission techniques and more recently broadcasters have switched to digital signals using digital transmission.

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.[2] This is the information equivalent of 55 newspapers per person per day in 1986, and 175 newspapers per person per day by 2007.[3]

Methods of broadcasting

Historically, there have been several methods used for broadcasting electronic media:

  • Telephone broadcasting (1881–1932): the earliest form of electronic broadcasting (not counting data services offered by stock telegraph companies from 1867, if ticker-tapes are excluded from the definition). Telephone broadcasting began with the advent of Théâtrophone ("Theatre Phone") systems, which were telephone-based distribution systems allowing subscribers to listen to live opera and theatre performances over telephone lines, created by French inventor Clément Ader in 1881. Telephone broadcasting also grew to include telephone newspaper services for news and entertainment programming which were introduced in the 1890s, primarily located in large European cities. These telephone-based subscription services were the first examples of electrical/electronic broadcasting and offered a wide variety of programming.
  • Radio broadcasting (experimentally from 1906, commercially from 1920); audio signals sent through the air as radio waves from a transmitter, picked up by an antenna and sent to a receiver. Stations can be linked in radio networks to broadcast common radio programs, either in broadcast syndication, simulcast or subchannels.
  • Television broadcasting (telecast), experimentally from 1925, commercially from the 1930s: an extension of radio to include video signals.
  • Cable radio (also called "cable FM", from 1928) and cable television (from 1932): both via coaxial cable, serving principally as transmission mediums for programming produced at either radio or television stations, with limited production of cable-dedicated programming.
  • Direct-broadcast satellite (DBS) (from circa 1974) and satellite radio (from circa 1990): meant for direct-to-home broadcast programming (as opposed to studio network uplinks and downlinks), provides a mix of traditional radio or television broadcast programming, or both, with dedicated satellite radio programming. (See also: Satellite television)
  • Webcasting of video/television (from circa 1993) and audio/radio (from circa 1994) streams: offers a mix of traditional radio and television station broadcast programming with dedicated internet radio–webcast programming.

Economic models

There are several means of providing financial support for continuous broadcasting:

Broadcasters may rely on a combination of these business models. For example, in the United States, National Public Radio (NPR) and the Public Broadcasting Service (PBS, television) supplement public membership subscriptions and corporate grants with grants from the Corporation for Public Broadcasting (CPB), which is funded by the federal government.

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".

Recorded broadcasts and live broadcasts


The first regular television broadcasts started in 1937. Broadcasts can be classified as "recorded" or "live". The former allows correcting errors, and removing superfluous or undesired material, rearranging it, applying slow-motion and repetitions, and other techniques to enhance the program. However, some live events like sports television can include some of the aspects including slow-motion clips of important goals/hits, etc., in between the live television telecast.

American radio-network broadcasters habitually forbade prerecorded broadcasts in the 1930s and 1940s requiring radio programs played for the Eastern and Central time zones to be repeated three hours later for the Pacific time zone (See: Effects of time on North American broadcasting). This restriction was dropped for special occasions, as in the case of the German dirigible airship Hindenburg disaster at Lakehurst, New Jersey, in 1937. During World War II, prerecorded broadcasts from war correspondents were allowed on U.S. radio. In addition, American radio programs were recorded for playback by Armed Forces Radio radio stations around the world.

A disadvantage of recording first is that the public may know the outcome of an event from another source, which may be a "spoiler". In addition, prerecording prevents live radio announcers from deviating from an officially approved script, 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-to-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 simply 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 news programme.

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 bandwidth to be shared.

The term "broadcast network" is often used to distinguish networks that broadcast an over-the-air television signals that can be received using a tuner (television) 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.

Social impact


The sequencing of content in a broadcast is called a schedule. As with all technological endeavors, a number of technical terms and slang have developed. A list of these terms can be found at List of broadcasting terms. Television and radio programs are distributed through radio broadcasting or cable, often both simultaneously. By coding signals and having a cable converter box with decoding equipment in homes, the latter also enables subscription-based channels, pay-tv and pay-per-view services.

In his essay, John Durham Peters wrote that communication is a tool used for dissemination. Durham stated, "Dissemination is a lens--sometimes a usefully distorting one--that helps us tackle basic issues such as interaction, presence, and space and time…on the agenda of any future communication theory in general" (Durham, 211). Dissemination focuses on the message being relayed from one main source to one large audience without the exchange of dialogue in between. There's chance for the message to be tweaked or corrupted once the main source releases it. There is really no way to predetermine how the larger population or audience will absorb the message. They can choose to listen, analyze, or simply ignore it. Dissemination in communication is widely used in the world of broadcasting.

Broadcasting focuses on getting one message out and it is up to the general public to do what they wish with it. Durham also states that broadcasting is used to address an open ended destination (Durham, 212). There are many forms of broadcast, but they all aim to distribute a signal that will reach the target audience. Broadcasting can arrange audiences into entire assemblies (Durham, 213).

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 his or her radio show and just talks into the microphone.[4] He or she does not expect immediate feedback from any listeners. The message is broadcast across airwaves throughout the community, but there the listeners cannot always respond immediately, especially since many radio shows are recorded prior to the actual air time.

List of over-the-air broadcasters (English-speaking countries)

United Kingdom

Ireland

USA

Canada

South Africa

Australia

New Zealand

Singapore

See also

Notes and references

Bibliography

  • Carey, James (1989) Communication as Culture, Routledge, New York and London, pp. 201–30
  • Kahn, Frank J., ed. Documents of American Broadcasting, fourth edition (Prentice-Hall, Inc., 1984).
  • Lichty Lawrence W., and Topping Malachi C., eds. American Broadcasting: A Source Book on the History of Radio and Television (Hastings House, 1975).
  • Meyrowitz, Joshua., Mediating Communication: What Happens? in Downing, J., Mohammadi, A., and Sreberny-Mohammadi, A., (eds) Questioning The Media (Sage, Thousand Oaks, 1995) pp. 39–53
  • Peters, John Durham. "Communication as Dissemination." Communication as…Perspectives on Theory. Thousand Oakes, CA: Sage, 2006. 211-22.
  • Thompson, J., The Media and Modernity, in Mackay, H and O'Sullivan, T (eds) The Media Reader: Continuity and Transformation., (Sage, London, 1999) pp. 12–27

Further reading

  • Gilbert, Sean; Nelson, John; Jacobs, George, World Radio TV Handbook.
  • Wells, Alan, ISBN 1-56750-245-8

External links

  • Radio Locator, for American radio station with format, power, and coverage information.
  • Jim Hawkins' Radio and Broadcast Technology Page – History of broadcast transmitter technology

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