Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model.[1] Broadcasting began with AM radio, which came into popular use around 1920 with the spread of vacuum tuberadio transmitters and receivers. Before this, most implementations of electronic communication (early radio, telephone, and telegraph) 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.[2] It was later adopted for describing the widespread distribution of information by printed materials[3] or by telegraph.[4] Examples applying it to "one-to-many" radio transmissions of an individual station to multiple listeners appeared as early as 1898.[5]
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".[6] Private or two-way telecommunications transmissions do not qualify under this definition. For example, amateur ("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 radio waves 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.[7]
The earliest broadcasting consisted of sending telegraph signals over the airwaves, using Morse code, a system developed in the 1830s by Samuel Morse, physicistJoseph Henry and Alfred Vail. They developed an electrical telegraph system which sent pulses of electric current along wires which controlled an electromagnet 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.[2]
In 1894, Italian inventor Guglielmo Marconi began developing a wireless communication using the then-newly discovered phenomenon of radio waves, showing by 1901 that they could be transmitted across the Atlantic Ocean.[8] 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, 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.[9]
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.[10] 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.[11]
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.[12] 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.[13] 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 analog signals 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 pressure of the sound waves.[14] 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:[15]
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.[16] This is the information equivalent of 55 newspapers per person per day in 1986, and 175 newspapers per person per day by 2007.[17]
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 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).[18][19]
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 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.[citation needed]
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, originally serving principally as transmission media for programming produced at either radio or television stations, but later expanding into a broad universe of cable-originated channels.
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)
Webcasting 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 and Internet television.
There are several means of providing financial support for continuous broadcasting:
Commercial broadcasting: 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 subscription fees.
Public broadcasting: 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.
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 models. 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".
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 Radioradio 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. Prerecording may be used to prevent announcers from deviating from an officially approved script 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-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 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 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.[21]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. Peters 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".[22]:211 Dissemination focuses on the message being relayed from one main source to one large audience 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.[22]:212 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.[22]: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.[22] 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.
↑ "Medical Advertising"Archived 1 August 2020 at the Wayback Machine , 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".
↑ "Wireless Telegraphy"Archived 27 July 2020 at the Wayback Machine , 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".
↑ Electronic Code of Federal Regulation. (28 September 2017). Retrieved 2 October 2017.
↑ Maccise, Diana Larrea; Montaser Marai (2018). "Mobile Journalism"(PDF). AlJazeera Media Training and Development Centre. Archived(PDF) from the original on 24 June 2021. Retrieved 24 June 2021.
↑ Vujovic, Ljubo (1998). "Tesla Biography". Tesla Memorial Society of New York. Archived from the original on 14 January 2016.
↑ Thompson, R.J. Jr. (2011). Crystal Clear: The Struggle for Reliable Communications Technology in World War II. Hoboken, NJ: Wiley. ISBN9781118104644.
↑ Théberge, P.; Devine, K.; Everrett, T (2015). Living Stereo: Histories and Cultures of Multichannel Sound. New York: Bloomsbury Publishing. ISBN9781623566654.
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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
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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 broadcast television, in which the television signal is transmitted over-the-air by radio waves and received by a television antenna attached to the television; or satellite television, in which the television signal is transmitted over-the-air by radio waves from a communications satellite orbiting the Earth, and received by a satellite dish antenna on the roof. FM radio programming, high-speed Internet, telephone services, and similar non-television services may also be provided through these cables. Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation.
Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high-definition television (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio in contrast to the narrower format (4:3) of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same bandwidth as a single analog channel, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2000. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:
A communications system or communication system is a collection of individual telecommunications networks systems, relay stations, tributary stations, and terminal equipment usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union.
In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some types of repeaters broadcast an identical signal, but alter its method of transmission, for example, on another frequency or baud rate.
In radio communication, a transceiver is an electronic device which is a combination of a radio transmitter and a receiver, hence the name. It can both transmit and receive radio waves using an antenna, for communication purposes. These two related functions are often combined in a single device to reduce manufacturing costs. The term is also used for other devices which can both transmit and receive through a communications channel, such as optical transceivers which transmit and receive light in optical fiber systems, and bus transceivers which transmit and receive digital data in computer data buses.
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz ; above the medium frequency band (MF), to the bottom of the VHF band.
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna with the purpose of signal transmission up to a radio receiver. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves.
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 transmissions, but also on the longwave and shortwave radio bands.
Radio broadcasting is the broadcasting of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based radio station, while in satellite radio the radio waves are broadcast by a satellite in Earth orbit. To receive the content the listener must have a broadcast radio receiver (radio). Stations are often affiliated with a radio network that provides content in a common radio format, either in broadcast syndication or simulcast, or both. Radio stations broadcast with several different types of modulation: AM radio stations transmit in AM, FM radio stations transmit in FM, which are older analog audio standards, while newer digital radio stations transmit in several digital audio standards: DAB, HD radio, DRM.
Terrestrial television or over-the-air television (OTA) is a type of television broadcasting in which the content is transmitted via radio waves from the terrestrial (Earth-based) transmitter of a TV station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in Canada and the United States it is called over-the-air or simply broadcast. This type of TV broadcast is distinguished from newer technologies, such as satellite television, in which the signal is transmitted to the receiver from an overhead satellite; cable television, in which the signal is carried to the receiver through a cable; and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is generally limited by the visual horizon to distances of 64–97 kilometres (40–60 mi), although under better conditions and with tropospheric ducting, signals can sometimes be received hundreds of kilometers distant.
Digital radio is the use of digital technology to transmit or receive across the radio spectrum. Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services.
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 because a lower frequency is used on the output. Broadcast FM/AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that converts the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker.
HD Radio (HDR) is a trademark for an in-band on-channel (IBOC) digital radio broadcast technology. HD radio generally simulcasts an existing analog radio station in digital format with less noise and with additional text information. HD Radio is used primarily by AM and FM radio stations in the United States, U.S. Virgin Islands, Canada, Mexico and the Philippines, with a few implementations outside North America.
Radio broadcasting has been used in the United States since the early 1920s to distribute news and entertainment to a national audience. In 1923, 1 percent of U.S. households owned at least one radio receiver, while a majority did by 1931 and 75 percent did by 1937. It was the first electronic "mass medium" technology, and its introduction, along with the subsequent development of sound films, ended the print monopoly of mass media. During the Golden Age of Radio it had a major cultural and financial impact on the country. However, the rise of television broadcasting in the 1950s relegated radio to a secondary status, as much of its programming and audience shifted to the new "sight joined with sound" service.
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 surface to any number of tuned receivers simultaneously.
Telecommunications engineering is a subfield of electronics engineering which seeks to design and devise systems of communication at a distance. The work ranges from basic circuit design to strategic mass developments. A telecommunication engineer is responsible for designing and overseeing the installation of telecommunications equipment and facilities, such as complex electronic switching systems, and other plain old telephone service facilities, optical fiber cabling, IP networks, and microwave transmission systems. Telecommunications engineering also overlaps with broadcast engineering.
Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves. They are received by another antenna connected to a radio receiver. In addition to communication, radio is used for radar, radio navigation, remote control, remote sensing, and other applications.
The Automatic Transmitter Identification System (ATIS) is a communications protocol used for the station identification of television channels carried on satellite television.
Television in Japan was introduced in 1939. However, experiments date back to the 1920s, with Kenjiro Takayanagi's pioneering experiments in electronic television. Television broadcasting was halted by World War II, after which regular television broadcasting began in 1950. After Japan developed the first HDTV systems in the 1960s, MUSE/Hi-Vision was introduced in the 1970s.
Telecommunication, often used in its plural form, is the transmission of information with an immediacy comparable to face-to-face communication. As such, slow communications technologies like postal mail and pneumatic tubes are excluded from the definition. Many transmission media have been used for telecommunications throughout history, from smoke signals, beacons, semaphore telegraphs, signal flags, and optical heliographs to wires and empty space made to carry electromagnetic signals. These paths of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent communication sessions. Several methods of long-distance communication before the modern era used sounds like coded drumbeats, the blowing of horns, and whistles. Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph, telephone, television, and radio.
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