- Note: broadcasting is also the old term for hand sowing.
Broadcasting is the distribution of audio and video signals (programs) to a number of recipients ("listeners" or "viewers") that belong to a large group. This group may be the public in general, or a relatively large audience within the public. Thus, an Internet channel may distribute text or music world-wide, while a public address system in (for example) a workplace may broadcast very limited ad hoc soundbites to a small population within its range.
The sequencing of content in a broadcast is called a Television and radio programs are distributed through radio broadcasting or cable, often both simultaneously. By coding signals and having decoding equipment in homes, the latter also enables subscription_based channels and pay-per-view services.
A broadcasting organisation may broadcast several programs at the same time, through several channels (frequencies), for example BBC One and Two. On the other hand, two or more organisations may share a channel and each use it during a fixed part of the day. Digital radio and digital television may also transmit multiplexed programming, with several channels compressed into one ensemble.
When broadcasting is done via the Internet the term webcasting is often used.
Broadcasting forms a very large segment of the mass media.
Broadcasting to a very narrow range of audience is called narrowcasting.
Business models of broadcasting
There are several dominant business models of broadcasting. Each differs in the method by which stations are funded:
Broadcasters may rely on a combination of these business models. For example, National Public Radio, a non-commercial network within the United States, receives grants from the Corporation for Public Broadcasting (which in turn receives funding from the U.S. government), by public membership, and by selling "extended credits" to corporations.
Recorded or live
One can distinguish between recorded and live broadcasts. 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.
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. This restriction was dropped for special occasions, as in the case of the German dirigible airship Hindenburg 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 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 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.
An intermediate form is a delay of a few seconds, to suppress obscenity and technical failures, or even coughing.
A broadcast may be distributed through several physical means. If coming directly from the studio at a single broadcast station, it is simply sent through the airchain to the transmitter. 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, and now mostly by satellite.
Distribution to stations or networks may also be through physical media, such as analogue or digital videotape, CD, DVD, and sometimes other formats. Usually these are included in another broadcast, such as when electronic news gathering 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 radio station or TV station to an antenna and receiver, or may come through cable TV or cable radio (or "wireless cable") via the station or directly from a network. The Internet may also bring either radio or TV to the recipient, especially with multicasting allowing the signal and bandwidth to be shared.
- NBMA Nonbroadcast Multiple Access Network
- www.eurotv.com, a West-European TV guide
- Waveguide (http://www.waveguide.co.uk/latest/news.htm) Broadcasting News
- Vernon Corea The Golden Voice of Radio Ceylon (http://www.vernoncorea.info)The story of broadcasting in Sri Lanka(Ceylon)
- Lyngsat.com (http://www.lyngsat.com/) Lyngsat Global Satellite Listings
- www.vizrt.com The world’s leading provider of real-time 2D and true 3D broadcast graphics
- Broadcasting Timeline (http://www.infoplease.com/ipea/A0151956.html)