Editing Broadcasting (section)

==Methods==
In a broadcast system, the central high-powered [[broadcast tower]] transmits a high-frequency [[electromagnetic wave]] to numerous receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The receiver is then [[Antenna tuner|tuned]] so as to pick up the high-frequency wave and a [[demodulator]] is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analog (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).<ref name="stallings-intro">{{cite book |last=Haykin |first=Simon |url=https://archive.org/details/communicationsy000simo |title=Communication Systems |publisher=John Wiley & Sons |year=2001 |isbn=978-0-471-17869-9 |edition=4th |pages=[https://archive.org/details/communicationsy000simo/page/n21 1]–3 |url-access=registration}}</ref><ref>[http://www.howstuffworks.com/radio.htm How Radio Works] {{Webarchive|url=https://web.archive.org/web/20160102215734/http://www.howstuffworks.com/radio.htm|date=2 January 2016}}, HowStuffWorks.com, 2006.</ref>

Historically, there have been several methods used for broadcasting [[electronic media]] audio and video to the general public:
* [[Telephone]] broadcasting (1881–1932): the earliest form of electronic broadcasting (not counting data services offered by stock [[Electrical telegraph|telegraph companies]] from 1867, if [[ticker tape|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 [[Radio programming|programming]] which were introduced in the 1890s, primarily located in large [[Europe]]an cities. These telephone-based [[subscription services]] were the first examples of electrical/electronic broadcasting and offered a wide variety of programming.{{Citation needed|date=October 2013}}
* [[Radio broadcasting]] (experimentally from 1906, commercially from 1920); [[sound|audio]] signals sent through the air as [[radio waves]] from a [[transmitter]], picked up by an [[radio antenna|antenna]] and sent to a [[tuner (radio)|receiver]]. [[Radio stations]] can be linked in [[radio network]]s to broadcast common [[radio program]]s, either in [[broadcast syndication]], [[simulcast]] or [[subchannel]]s.
** [[Television]] broadcasting (telecast), experimentally from 1925, [[commercial television|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]],  originally serving principally as transmission media for programming produced at either radio or [[television station]]s, but later expanding into a broad universe of cable-originated [[cable channel|channels]].
* [[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 down-links), provides a mix of traditional radio or television broadcast programming, or both, with dedicated satellite radio programming. (See also: [[Satellite television]])
* [[Webcast#Origins|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]] and [[Internet television]].