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Broadcasting is the
distribution Distribution may refer to: Mathematics * Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a vari ...
of
audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of sou ...
or video content to a dispersed
audience An audience is a group of people who participate in a show or encounter a work of art, literature (in which they are called "readers"), theatre, music (in which they are called "listeners"), video games (in which they are called "players"), or ...
via any electronic mass communications medium, but typically one using the
electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from b ...
(
radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (shor ...
s), in a one-to-many model. Broadcasting began with
AM radio AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmi ...
, which came into popular use around 1920 with the spread of vacuum tube
radio transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to th ...
s and receivers. Before this, all forms of electronic communication (early radio, telephone, and
telegraph Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas p ...
) were one-to-one, 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 or by telegraph. Examples applying it to "one-to-many" radio transmissions of an individual station to multiple listeners appeared as early as 1898. 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 Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broadc ...
). 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 Public broadcasting involves radio, television and other electronic media outlets whose primary mission is public service. Public broadcasters receive funding from diverse sources including license fees, individual contributions, public financing ...
,
community radio Community radio is a radio service offering a third model of radio broadcasting in addition to commercial and public broadcasting. Community stations serve geographic communities and communities of interest. They broadcast content that is popula ...
and public television, and private commercial radio and
commercial television Commercial broadcasting (also called private broadcasting) is the broadcasting of television programs and radio programming by privately owned corporate media, as opposed to state sponsorship. It was the United States′ first model of radio (an ...
. 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". Private or two-way telecommunications transmissions do not qualify under this definition. For example,
amateur An amateur () is generally considered a person who pursues an avocation independent from their source of income. Amateurs and their pursuits are also described as popular, informal, self-taught, user-generated, DIY, and hobbyist. History Hist ...
("ham") and
citizens band Citizens band radio (also known as CB radio), used in many countries, is a land mobile radio system, a system allowing short-distance person-to-many persons bidirectional voice communication among individuals, using two way radios operating on ...
(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
radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (shor ...
s 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 Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broadc ...
(which also retransmits OTA stations with their
consent Consent occurs when one person voluntarily agrees to the proposal or desires of another. It is a term of common speech, with specific definitions as used in such fields as the law, medicine, research, and sexual relationships. Consent as und ...
), 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.


History

The earliest broadcasting consisted of sending telegraph signals over the airwaves, using
Morse code Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one ...
, a system developed in the 1830s by Samuel Morse,
physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...
Joseph Henry and
Alfred Vail Alfred Lewis Vail (September 25, 1807 – January 18, 1859) was an American machinist and inventor. Along with Samuel Morse, Vail was central in developing and commercializing American telegraphy between 1837 and 1844. Vail and Morse were the f ...
. They developed an electrical telegraph system which sent pulses of electric current along wires which controlled an
electromagnet An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the ...
that was located at the receiving end of the telegraph system. A code was needed to transmit natural language using only these pulses, and the silence between them. Morse therefore developed the forerunner to modern International Morse code. This was particularly important for ship-to-ship and ship-to-shore communication, but it became increasingly important for business and general news reporting, and as an arena for personal communication by radio amateurs. In 1894, Italian inventor
Guglielmo Marconi Guglielmo Giovanni Maria Marconi, 1st Marquis of Marconi (; 25 April 187420 July 1937) was an Italian inventor and electrical engineer, known for his creation of a practical radio wave-based wireless telegraph system. This led to Marconi bei ...
began developing a wireless communication using the then-newly discovered phenomenon of
radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (shor ...
s, showing by 1901 that they could be transmitted across the Atlantic Ocean. This was the start of wireless telegraphy by radio. Audio radio broadcasting began experimentally in the first decade of the 20th century. On 17 December 1902, a transmission from the Marconi station in
Glace Bay Glace Bay (Scottish Gaelic: ''Glasbaidh'') is a community in the eastern part of the Cape Breton Regional Municipality in Nova Scotia, Canada. It forms part of the general area referred to as Industrial Cape Breton. Formerly an incorporated t ...
, Nova Scotia, Canada, became the world's first radio message to cross the Atlantic from North America. In 1904, a commercial service was established to transmit nightly news summaries to subscribing ships, which incorporated them into their onboard newspapers. World War I accelerated the development of radio for
military communications Military communications or military signals involve all aspects of communications, or conveyance of information, by armed forces. Military communications span from pre-history to the present. The earliest military communications were delivered b ...
. After the war, commercial radio
AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmi ...
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. On 25 March 1925,
John Logie Baird John Logie Baird FRSE (; 13 August 188814 June 1946) was a Scottish inventor, electrical engineer, and innovator who demonstrated the world's first live working television system on 26 January 1926. He went on to invent the first publicly demo ...
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 Mechanical television or mechanical scan television is a television system that relies on a mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror drum, to scan the scene and generate the video signal, and a si ...
. It formed the basis of experimental broadcasts done by the
British Broadcasting Corporation #REDIRECT BBC Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...
beginning on 30 September 1929. However, for most of the 20th century, televisions depended on the
cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictu ...
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 Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF ...
and
UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...
spectrum.
Satellite broadcasting A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotop ...
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
analog signal An analog signal or analogue signal (see spelling differences) 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 c ...
s using
analog transmission Analog transmission is a transmission method of conveying information using a continuous signal which varies in amplitude, phase, or some other property in proportion to that information. It could be the transfer of an analog signal, using an an ...
techniques but in the 2000s, broadcasters
switched Switched may refer to: * Switched (band) Switched (previously depicted as Sw1tched) was a nu metal band from Cleveland, Ohio. History Forming in 1999 as Sw1tch, the band played shows around Ohio and released a demo entitled ''Fuckin' Demo''. T ...
to
digital signals A digital signal is a signal that represents data as a sequence of discrete values; at any given time it can only take on, at most, one of a finite number of values. This contrasts with an analog signal, which represents continuous values; at ...
using
digital transmission Data transmission and data reception or, more broadly, data communication or digital communications is the transfer and reception of data in the form of a digital bitstream or a digitized analog signal transmitted over a point-to-point or ...
. An analog signal is any
continuous signal In mathematical dynamics, discrete time and continuous time are two alternative frameworks within which variables that evolve over time are modeled. Discrete time Discrete time views values of variables as occurring at distinct, separate "po ...
representing some other quantity, i.e., ''analogous'' to another quantity. For example, in an analog
audio signal An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals, or a series of binary numbers for digital signals. Audio signals have frequencies in the audio frequency range of ro ...
, the instantaneous signal voltage varies continuously with the pressure of the sound waves. In contrast, a digital signal represents the original time-varying quantity as a
sampled Sample or samples may refer to: Base meaning * Sample (statistics), a subset of a population – complete data set * Sample (signal), a digital discrete sample of a continuous analog signal * Sample (material), a specimen or small quantity of so ...
sequence of quantized values which imposes some
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
and
dynamic range Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base- ...
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. *
Analog audio Analog recording is a technique used for the recording of analog signals which, among many possibilities, allows analog audio for later playback. Analog audio recording began with mechanical systems such as the phonautograph and phonograph. L ...
radio (AM, FM) vs. Digital audio radio ( HD Radio), Digital Audio Broadcasting (DAB), Satellite radio and
Digital Radio Mondiale Digital Radio Mondiale (DRM; ''mondiale'' being Italian and French for "worldwide") is a set of digital audio broadcasting technologies designed to work over the bands currently used for analogue radio broadcasting including AM broadcasting—p ...
(DRM) *
Analog television Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog s ...
vs. Digital television * Wireless 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 The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
."The World's Technological Capacity to Store, Communicate, and Compute Information"
, Martin Hilbert and Priscila López (2011), Science, 332(6025), 60–65; free access to the article through here: martinhilbert.net/WorldInfoCapacity.html
This is the information equivalent of 55 newspapers per person per day in 1986, and 175 newspapers per person per day by 2007.


Methods

In a broadcast system, the central high-powered
broadcast tower Radio masts and towers are typically tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two main types: guyed and self-supporting structures. They are among the tallest human-mad ...
transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The receiver is then tuned so as to pick up the high-frequency wave and a
demodulator Demodulation is extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated ...
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). Historically, there have been several methods used for broadcasting
electronic media Electronic media are media that use electronics or electromechanical means for the audience to access the content. This is in contrast to static media (mainly print media), which today are most often created digitally, but do not require el ...
audio and video to the general public: * Telephone broadcasting (1881–1932): the earliest form of electronic broadcasting (not counting data services offered by stock
telegraph companies Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas p ...
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 Clément Ader (2 April 1841 – 3 May 1925) was a French inventor and engineer who was born near Toulouse in Muret, Haute-Garonne, and died in Toulouse. He is remembered primarily for his pioneering work in aviation. In 1870 he was also one of ...
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 The subscription business model is a business model in which a customer must pay a recurring price at regular intervals for access to a product or service. The model was pioneered by publishers of books and periodicals in the 17th century, and ...
were the first examples of electrical/electronic broadcasting and offered a wide variety of programming. * Radio broadcasting (experimentally from 1906, commercially from 1920);
audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of sou ...
signals sent through the air as
radio waves Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...
from a transmitter, picked up by an antenna and sent to a receiver. Radio stations can be linked in radio networks to broadcast common radio programs, either in
broadcast syndication Broadcast syndication is the practice of leasing the right to broadcasting television shows and radio programs to multiple television stations and radio stations, without going through a broadcast network. It is common in the United States wher ...
, simulcast or
subchannel In broadcasting, digital subchannels are a method of transmitting more than one independent program stream simultaneously from the same digital radio or television station on the same radio frequency channel. This is done by using data compressi ...
s. * Television broadcasting (telecast), experimentally from 1925,
commercially Commerce is the large-scale organized system of activities, functions, procedures and institutions directly and indirectly related to the exchange (buying and selling) of goods and services among two or more parties within local, regional, nation ...
from the 1930s: an extension of radio to include video signals. *
Cable radio Cable radio or cable FM is a concept similar to that of cable television, bringing radio broadcasting into homes and businesses via coaxial cable. It is generally used for the same reason as cable TV was in its early days when it was "community ...
(also called "cable FM", from 1928) and
cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broadc ...
(from 1932): both via
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulato ...
, originally serving principally as transmission media for programming produced at either radio or
television station A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth ...
s, but later expanding into a broad universe of cable-originated
channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Austral ...
. * Direct-broadcast satellite (DBS) (from c. 1974) and satellite radio (from c. 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 Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commo ...
) *
Webcasting A webcast is a media presentation distributed over the Internet using streaming media technology to distribute a single content source to many simultaneous listeners/viewers. A webcast may either be distributed live or on demand. Essentially, we ...
of video/television (from c. 1993) and audio/radio (from c. 1994) streams: offers a mix of traditional radio and television station broadcast programming with dedicated
Internet radio Online radio (also web radio, net radio, streaming radio, e-radio, IP radio, Internet radio) is a digital audio service transmitted via the Internet. Broadcasting on the Internet is usually referred to as webcasting since it is not transmitted ...
and
Internet television Streaming television is the digital distribution of television content, such as TV shows, as streaming media delivered over the Internet. Streaming television stands in contrast to dedicated terrestrial television delivered by over-the-air a ...
.


Economic models

There are several means of providing financial support for continuous broadcasting: *
Commercial broadcasting Commercial broadcasting (also called private broadcasting) is the broadcasting of television programs and radio programming by privately owned corporate media, as opposed to state sponsorship. It was the United States′ first model of radio (an ...
: for-profit, usually privately owned stations, channels, networks, or services providing programming to the public, supported by the sale of air time to advertisers for radio or television advertisements during or in breaks between programs, often in combination with cable or
pay cable Pay television, also known as subscription television, premium television or, when referring to an individual service, a premium channel, refers to subscription-based television services, usually provided by multichannel television providers, but ...
subscription fees. *
Public broadcasting Public broadcasting involves radio, television and other electronic media outlets whose primary mission is public service. Public broadcasters receive funding from diverse sources including license fees, individual contributions, public financing ...
: usually non-profit, publicly owned stations or networks supported by license fees, government funds, grants from foundations, corporate underwriting, audience memberships, contributions or a combination of these. * Community broadcasting: a form of mass media in which a
television station A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth ...
, or a radio station, is owned, operated or programmed, by a community group to provide programs of local interest known as
local programming The terms local programme, local programming, local content or local television refers to a television program made by a television station or independent television producer for broadcast only within the station's transmission area or televisi ...
. Community stations are most commonly operated by
non-profit group A nonprofit organization (NPO) or non-profit organisation, also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collective, public or social benefit, in co ...
s or
cooperatives A cooperative (also known as co-operative, co-op, or coop) is "an autonomous association of persons united voluntarily to meet their common economic, social and cultural needs and aspirations through a jointly owned and democratically-contro ...
; however, in some cases they may be operated by a local
college A college (Latin: ''collegium'') is an educational institution or a constituent part of one. A college may be a degree-awarding tertiary educational institution, a part of a collegiate or federal university, an institution offering ...
or university, a
cable company This is a list of cable television providers by country. Andorra * Mútua Elèctrica(Cable Mútua), Sant Julià de Lória) Argentina * Cablevisión *DirecTV * * *Gigared *Telered Australia *Foxtel *Fetch TV Austria *BKF *LIWEST *Salzburg AG ...
or a municipal government. * Internet Webcast: the audience pays to recharge and buy virtual gifts for the anchor, and the platform converts the gifts into virtual currency. The anchor withdraws the virtual currency, which is drawn by the platform. If the anchor belongs to a trade union, it will be settled by the trade union and the live broadcasting platform, and the anchor will get the salary and part of the bonus. This is the most common profit model of live broadcast products. Broadcasters may rely on a combination of these
business model A business model describes how an organization creates, delivers, and captures value,''Business Model Generation'', Alexander Osterwalder, Yves Pigneur, Alan Smith, and 470 practitioners from 45 countries, self-published, 2010 in economic, soci ...
s. 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 The Corporation for Public Broadcasting (CPB) is an American publicly funded non-profit corporation, created in 1967 to promote and help support public broadcasting. The corporation's mission is to ensure universal access to non-commercial, ...
(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 The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdictio ...
restrictions, which prohibit the advocacy of a product or a "call to action".


Recorded and live forms

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 Slow motion (commonly abbreviated as slo-mo or slow-mo) is an effect in film-making whereby time appears to be slowed down. It was invented by the Austrian priest August Musger in the early 20th century. This can be accomplished through the use ...
and repetitions, and other techniques to enhance the program. However, some live events like
sports television The broadcasting of sports events (also known as a sportscast) is the live coverage of sports as a television program, on radio, and other broadcasting media. It usually involves one or more sports commentators describing events as they happen. ...
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 The scheduling of television programming in North America (namely the United States, Canada, and Mexico) must cope with different time zones. The United States (excluding territories) has six time zones ( Hawaii–Aleutian, Alaska, Pacific, Mou ...
). This restriction was dropped for special occasions, as in the case of the German dirigible airship '' Hindenburg'' disaster at
Lakehurst, New Jersey Lakehurst is a borough in Ocean County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 2,654,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 The American Forces Network (AFN) is a government television and radio broadcast service the United States Armed Forces, U.S. military provides to those stationed or assigned overseas. Headquartered at Fort George G. Meade, Maryland, AFN's br ...
radio stations around the world. 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 Spoiler is a security vulnerability on modern computer central processing units that use speculative execution. It exploits side-effects of speculative execution to improve the efficiency of Rowhammer and other related memory and cache attacks. ...
". Prerecording may be used to prevent
announcer An announcer is a voice artist who relays information to the audience of a broadcast media programme or live event. Television and other media Some announcers work in television production, radio or filmmaking, usually providing narrations, ...
s from deviating from an officially approved
script Script may refer to: Writing systems * Script, a distinctive writing system, based on a repertoire of specific elements or symbols, or that repertoire * Script (styles of handwriting) ** Script typeface, a typeface with characteristics of ha ...
during a live radio broadcast, as occurred with propaganda broadcasts from Germany in the 1940s and with
Radio Moscow Radio Moscow ( rus, Pадио Москва, r=Radio Moskva), also known as Radio Moscow World Service, was the official international broadcasting station of the Union of Soviet Socialist Republics until 1993. It was reorganized with a new name ...
in the 1980s. Many events are advertised as being live, although they are often "recorded live" (sometimes called "
live Live may refer to: Arts, entertainment, and media Films * ''Live!'' (2007 film), 2007 American film * ''Live'' (2014 film), a 2014 Japanese film *'' ''Live'' (Apocalyptica DVD) Music * Live (band), American alternative rock band * List of album ...
-to- tape"). This is particularly true of performances of musical artists on radio when they visit for an in-studio
concert A concert is a live music performance in front of an audience. The performance may be by a single musician, sometimes then called a recital, or by a musical ensemble, such as an orchestra, choir, or band. Concerts are held in a wide variety ...
performance. Similar situations have occurred in television production ("'' The Cosby Show'' is recorded in front of a live television studio
audience An audience is a group of people who participate in a show or encounter a work of art, literature (in which they are called "readers"), theatre, music (in which they are called "listeners"), video games (in which they are called "players"), or ...
") 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 A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth ...
, it is sent through the
studio/transmitter link A studio transmitter link (or STL) sends a radio station's or television station's audio and video from the broadcast studio or origination facility to a radio transmitter, television transmitter or uplink facility in another location. This is ...
to the transmitter and hence from the television antenna located on the
radio masts and towers Radio masts and towers are typically tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two main types: guyed and self-supporting structures. They are among the tallest human-mad ...
out to the world. Programming may also come through a
communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. ...
, played either live or recorded for later transmission. Networks of stations may simulcast the same programming at the same time, originally via
microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency rang ...
link, now usually by satellite. Distribution to stations or networks may also be through physical media, such as magnetic tape, compact disc (CD),
DVD The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kin ...
, and sometimes other formats. Usually these are included in another broadcast, such as when
electronic news gathering Electronic news-gathering (ENG) or electronic journalism (EJ) is usage of electronic video and audio technologies by reporters to gather and present news instead of using film cameras. The term was coined during the rise of videotape tech ...
(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 radio station or
television station A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth ...
to an antenna and
radio receiver In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. T ...
, or may come through
cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broadc ...
or
cable radio Cable radio or cable FM is a concept similar to that of cable television, bringing radio broadcasting into homes and businesses via coaxial cable. It is generally used for the same reason as cable TV was in its early days when it was "community ...
(or " wireless cable") via the station or directly from a network. The Internet may also bring either
internet radio Online radio (also web radio, net radio, streaming radio, e-radio, IP radio, Internet radio) is a digital audio service transmitted via the Internet. Broadcasting on the Internet is usually referred to as webcasting since it is not transmitted ...
or streaming media television to the recipient, especially with multicasting allowing the signal and
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
to be shared. The term "
broadcast network A terrestrial network (or broadcast network in the United States) is a group of radio stations, television stations, or other electronic media outlets, that form an agreement to air, or broadcast, content from a centralized source. For example, ...
" is often used to distinguish networks that broadcast an over-the-air television signals that can be received using a
tuner (television) A tuner is a subsystem that receives radio frequency (RF) transmissions, such as FM broadcasting, and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually ...
inside a
television set A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
with a television antenna from so-called networks that are broadcast only via
cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broadc ...
(
cablecast Narrowcasting is the dissemination of information (usually via Internet, radio, newspaper, or television) to a narrow audience, rather than to the broader public at-large. Related to niche marketing or target marketing, narrowcasting involves aim ...
) or
satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commo ...
that uses a
dish antenna A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or pa ...
. The term "
broadcast television Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals. Analog television systems were standardized by ...
" 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 This glossary of terms used in broadcasting is a list of definitions of terms and concepts related to both radio and television broadcasting, along with the industry in general. A ), a Japanese television and radio broadcaster., 7 ...
. Television and radio programs are distributed through radio broadcasting or cable, often both simultaneously. By coding signals and having a
cable converter box A cable converter box or television converter box is an electronic tuning device that transposes/converts channels from a cable television service to an analog RF signal on a single channel, usually VHF or 4, or to a different output for di ...
with decoding equipment in homes, the latter also enables subscription-based channels,
pay-tv Pay television, also known as subscription television, premium television or, when referring to an individual service, a premium channel, refers to subscription-based television services, usually provided by multichannel television providers, bu ...
and pay-per-view services. In his essay,
John Durham Peters John Durham Peters (born 1958) is the María Rosa Menocal Professor of English and of Film & Media Studies at Yale University. A media historian and social theorist, he has authored a number of noted scholarly works. His first book, '' Speaking into ...
wrote that communication is a tool used for dissemination. Peters stated, "
Dissemination To disseminate (from lat. ''disseminare'' "scattering seeds"), in the field of communication, is to broadcast a message to the public without direct feedback from the audience. Meaning Dissemination takes on the theory of the traditional view ...
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 Communication theory is a proposed description of communication phenomena, the relationships among them, a storyline describing these relationships, and an argument for these three elements. Communication theory provides a way of talking about a ...
in general". Dissemination focuses on the message being relayed from one main source to one large
audience An audience is a group of people who participate in a show or encounter a work of art, literature (in which they are called "readers"), theatre, music (in which they are called "listeners"), video games (in which they are called "players"), or ...
without the exchange of dialogue in between. It is possible for the message to be changed or corrupted by government officials once the main source releases it. There is no way to predetermine how the larger population or audience will absorb the message. They can choose to listen, analyze, or ignore it. Dissemination in communication is widely used in the world of broadcasting. 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 An audience is a group of people who participate in a show or encounter a work of art, literature (in which they are called "readers"), theatre, music (in which they are called "listeners"), video games (in which they are called "players"), or ...
. 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 his or her radio show and just talks into the microphone. 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.


Broadcast engineering

Broadcast engineering is the field of electrical engineering, and now to some extent
computer engineering Computer engineering (CoE or CpE) is a branch of electrical engineering and computer science that integrates several fields of computer science and electronic engineering required to develop computer hardware and software. Computer engineers ...
and information technology, which deals with radio and television broadcasting.
Audio engineering Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...
and
RF engineering Radio-frequency (RF) engineering is a subset of electronic engineering involving the application of transmission line, waveguide, antenna and electromagnetic field principles to the design and application of devices that produce or use signals ...
are also essential parts of broadcast engineering, being their own subsets of electrical engineering. Broadcast engineering involves both the
studio A studio is an artist or worker's workroom. This can be for the purpose of acting, architecture, painting, pottery ( ceramics), sculpture, origami, woodworking, scrapbooking, photography, graphic design, filmmaking, animation, industrial desig ...
and transmitter aspects (the entire
airchain In broadcast engineering for radio or television, the airchain or transmission chain (UK) (sometimes air chain (US) or just chain (UK)) is the path or route an audio or video signal takes on its way through a radio station or television station. ...
), as well as remote broadcasts. Every station has a broadcast
engineer Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the lim ...
, though one may now serve an entire station group in a city. In small media markets the engineer may work on a contract basis for one or more stations as needed.


See also


Notes and references


Bibliography

* Carey, James (1989), ''Communication as Culture'', New York and London: Routledge, 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'' (Thousand Oaks, CA: Sage 1995), pp. 39–53 * * Thompson, J., ''The Media and Modernity'', in Mackay, H., and O'Sullivan, T. (eds), ''The Media Reader: Continuity and Transformation'' (London: Sage, 1999), pp. 12–27
International bibliography – History of wireless and radio broadcasting


Further reading

* Barnouw Erik. ''The Golden Web'' (Oxford University Press, 1968); ''The Sponsor'' (1978); ''A Tower in Babel'' (1966). * Covert Cathy, and Stevens John L. ''Mass Media Between the Wars'' (Syracuse University Press, 1984). * Tim Crook; ''International Radio Journalism: History, Theory and Practice'' Routledge, 1998 * John Dunning; ''On the Air: The Encyclopedia of Old-Time Radio'' Oxford University Press, 1998 * Ewbank Henry and Lawton Sherman P. ''Broadcasting: Radio and Television'' (Harper & Brothers, 1952). * Maclaurin W. Rupert. ''Invention and Innovation in the Radio Industry'' (The Macmillan Company, 1949). * Robert W. McChesney; ''Telecommunications, Mass Media, and Democracy: The Battle for the Control of U.S. Broadcasting, 1928-1935'' Oxford University Press, 1994 * Gwenyth L. Jackaway; ''Media at War: Radio's Challenge to the Newspapers, 1924-1939'' Praeger Publishers, 1995 * Lazarsfeld Paul F. ''The People Look at Radio'' (University of North Carolina Press, 1946). * Schramm Wilbur, ed. ''Mass Communications'' (University of Illinois Press, 1960). * Schwoch James. ''The American Radio Industry and Its Latin American Activities, 1900-1939'' (University of Illinois Press, 1990). * Slater Robert. ''This ... is CBS: A Chronicle of 60 Years'' (Prentice Hall, 1988). * Sterling Christopher H. ''Electronic Media, A Guide to Trends in Broadcasting and Newer Technologies 1920-1983'' (Praeger, 1984). * Sterling Christopher, and Kittross John M. ''Stay Tuned: A Concise History of American Broadcasting'' (Wadsworth, 1978). * Wells, Alan
''World Broadcasting: A Comparative View''
Greenwood Publishing Group, 1996.


External links


Radio Locator
for American radio station with format, power, and coverage information.

– History of broadcast transmitter

– Broadcast Industry Glossary {{Authority control Telecommunications