Radio broadcasting is transmission by radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both. The signal types can be either analog audio or digital audio.
The thermionic valve was invented in 1904 by the English physicist John Ambrose Fleming. He developed a device he called an "oscillation valve" (because it passes current in only one direction). The heated filament, or cathode, was capable of thermionic emission of electrons that would flow to the plate (or anode) when it was at a higher voltage. Electrons, however, could not pass in the reverse direction because the plate was not heated and thus not capable of thermionic emission of electrons. Later known as the Fleming valve, it could be used as a rectifier of alternating current and as a radio wave detector. This greatly improved the crystal set which rectified the radio signal using an early solid-state diode based on a crystal and a so-called cat's whisker. However, what was still required was an amplifier.
The triode (mercury-vapor filled with a control grid) was patented on March 4, 1906, by the Austrian Robert von Lieben independent from that, on October 25, 1906, Lee De Forest patented his three-element Audion. It wasn't put to practical use until 1912 when its amplifying ability became recognized by researchers.
By about 1920, valve technology had matured to the point where radio broadcasting was quickly becoming viable. However, an early audio transmission that could be termed a broadcast may have occurred on Christmas Eve in 1906 by Reginald Fessenden, although this is disputed. While many early experimenters attempted to create systems similar to radiotelephone devices by which only two parties were meant to communicate, there were others who intended to transmit to larger audiences. Charles Herrold started broadcasting in California in 1909 and was carrying audio by the next year. (Herrold's station eventually became KCBS).
In The Hague, the Netherlands, PCGG started broadcasting on November 6, 1919, making it, arguably the first commercial broadcasting station. In 1916, Frank Conrad, an electrical engineer employed at the Westinghouse Electric Corporation, began broadcasting from his Wilkinsburg, Pennsylvania garage with the call letters 8XK. Later, the station was moved to the top of the Westinghouse factory building in East Pittsburgh, Pennsylvania. Westinghouse relaunched the station as KDKA on November 2, 1920, as the first commercially licensed radio station in America. The commercial broadcasting designation came from the type of broadcast license; advertisements did not air until years later. The first licensed broadcast in the United States came from KDKA itself: the results of the Harding/Cox Presidential Election. The Montreal station that became CFCF began broadcast programming on May 20, 1920, and the Detroit station that became WWJ began program broadcasts beginning on August 20, 1920, although neither held a license at the time.
In 1920, wireless broadcasts for entertainment began in the UK from the Marconi Research Centre 2MT at Writtle near Chelmsford, England. A famous broadcast from Marconi's New Street Works factory in Chelmsford was made by the famous soprano Dame Nellie Melba on 15 June 1920, where she sang two arias and her famous trill. She was the first artist of international renown to participate in direct radio broadcasts. The 2MT station began to broadcast regular entertainment in 1922. The BBC was amalgamated in 1922 and received a Royal Charter in 1926, making it the first national broadcaster in the world, followed by Czech Radio and other European broadcasters in 1923.
Radio Argentina began regularly scheduled transmissions from the Teatro Coliseo in Buenos Aires on August 27, 1920, making its own priority claim. The station got its license on November 19, 1923. The delay was due to the lack of official Argentine licensing procedures before that date. This station continued regular broadcasting of entertainment and cultural fare for several decades.
Radio in education soon followed and colleges across the U.S. began adding radio broadcasting courses to their curricula. Curry College in Milton, Massachusetts introduced one of the first broadcasting majors in 1932 when the college teamed up with WLOE in Boston to have students broadcast programs.
Broadcasting service (short: Broadcasting (BS) | also: broadcasting radiocommunication service) is – according to Article 1.38 of the International Telecommunication Union´s (ITU) Radio Regulations (RR) – defined as «A radiocommunication service in which the transmission are intended for direct reception by the general public. This service may include sound transmissions, television transmissions or other types of transmission (CS).» Definitions identical to those contained in the Annexes to the Constitution and Convention of the International Telecommunication Union (Geneva, 1992) are marked "(CS)" or "(CV)" respectively.
A radio broadcasting station is usually associated with wireless transmission, though in practice broadcasting transmission (sound and television) take place using both wires and radio waves. The point of this is that anyone with the appropriate receiving technology can receive the broadcast.
In line to ITU Radio Regulations (article1.61) each broadcasting station shall be classified by the service in which it operates permanently or temporarily.
Broadcasting by radio takes several forms. These include AM and FM stations. There are several subtypes, namely commercial broadcasting, non-commercial educational (NCE) public broadcasting and non-profit varieties as well as community radio, student-run campus radio stations, and hospital radio stations can be found throughout the world. Many stations broadcast on shortwave bands using AM technology that can be received over thousands of miles (especially at night). For example, the BBC, VOA, VOR, and Deutsche Welle have transmitted via shortwave to Africa and Asia. These broadcasts are very sensitive to atmospheric conditions and solar activity.
Nielsen Audio, formerly known as Arbitron, the United States-based company that reports on radio audiences, defines a "radio station" as a government-licensed AM or FM station; an HD Radio (primary or multicast) station; an internet stream of an existing government-licensed station; one of the satellite radio channels from XM Satellite Radio or Sirius Satellite Radio; or, potentially, a station that is not government licensed.
AM stations were the earliest broadcasting stations to be developed. AM refers to amplitude modulation, a mode of broadcasting radio waves by varying the amplitude of the carrier signal in response to the amplitude of the signal to be transmitted. The medium-wave band is used worldwide for AM broadcasting. Europe also uses the long wave band. In response to the growing popularity of FM stereo radio stations in the late 1980s and early 1990s, some North American stations began broadcasting in AM stereo, though this never gained popularity, and very few receivers were ever sold.
The signal is subject to interference from electrical storms (lightning) and other electromagnetic interference (EMI). One advantage of AM radio signal is that it can be detected (turned into sound) with simple equipment. If a signal is strong enough, not even a power source is needed; building an unpowered crystal radio receiver was a common childhood project in the early decades of AM broadcasting.
AM broadcasts occur on North American airwaves in the medium wave frequency range of 525 to 1705 kHz (known as the “standard broadcast band”). The band was expanded in the 1990s by adding nine channels from 1605 to 1705 kHz. Channels are spaced every 10 kHz in the Americas, and generally every 9 kHz everywhere else.
AM transmissions cannot be ionospherically propagated during the day due to strong absorption in the D-layer of the ionosphere. In a crowded channel environment, this means that the power of regional channels which share a frequency must be reduced at night or directionally beamed in order to avoid interference, which reduces the potential nighttime audience. Some stations have frequencies unshared with other stations in North America; these are called clear-channel stations. Many of them can be heard across much of the country at night. During the night, absorption largely disappears and permits signals to travel to much more distant locations via ionospheric reflections. However, fading of the signal can be severe at night.
AM radio transmitters can transmit audio frequencies up to 15 kHz (now limited to 10 kHz in the US due to FCC rules designed to reduce interference), but most receivers are only capable of reproducing frequencies up to 5 kHz or less. At the time that AM broadcasting began in the 1920s, this provided adequate fidelity for existing microphones, 78 rpm recordings, and loudspeakers. The fidelity of sound equipment subsequently improved considerably, but the receivers did not. Reducing the bandwidth of the receivers reduces the cost of manufacturing and makes them less prone to interference. AM stations are never assigned adjacent channels in the same service area. This prevents the sideband power generated by two stations from interfering with each other. Bob Carver created an AM stereo tuner employing notch filtering that demonstrated that an AM broadcast can meet or exceed the 15 kHz baseband bandwidth allotted to FM stations without objectionable interference. After several years, the tuner was discontinued. Bob Carver had left the company and the Carver Corporation later cut the number of models produced before discontinuing production completely.
See shortwave for the differences between shortwave, medium wave, and long wave spectra. Shortwave is used largely for national broadcasters, international propaganda, or religious broadcasting organizations.
FM refers to frequency modulation, and occurs on VHF airwaves in the frequency range of 88 to 108 MHz everywhere except Japan and Russia. Russia, like the former Soviet Union, uses 65.9 to 74 MHz frequencies in addition to the world standard. Japan uses the 76 to 90 MHz frequency band.
Edwin Howard Armstrong invented FM radio to overcome the problem of radio-frequency interference (RFI), which plagued AM radio reception. At the same time, greater fidelity was made possible by spacing stations further apart in the radio frequency spectrum. Instead of 10 kHz apart, as on the AM band in the US, FM channels are 200 kHz (0.2 MHz) apart. In other countries, greater spacing is sometimes mandatory, such as in New Zealand, which uses 700 kHz spacing (previously 800 kHz). The improved fidelity made available was far in advance of the audio equipment of the 1940s, but wide interchannel spacing was chosen to take advantage of the noise-suppressing feature of wideband FM.
Bandwidth of 200 kHz is not needed to accommodate an audio signal — 20 kHz to 30 kHz is all that is necessary for a narrowband FM signal. The 200 kHz bandwidth allowed room for ±75 kHz signal deviation from the assigned frequency, plus guard bands to reduce or eliminate adjacent channel interference. The larger bandwidth allows for broadcasting a 15 kHz bandwidth audio signal plus a 38 kHz stereo "subcarrier"—a piggyback signal that rides on the main signal. Additional unused capacity is used by some broadcasters to transmit utility functions such as background music for public areas, GPS auxiliary signals, or financial market data.
The AM radio problem of interference at night was addressed in a different way. At the time FM was set up, the available frequencies were far higher in the spectrum than those used for AM radio - by a factor of approximately 100. Using these frequencies meant that even at far higher power, the range of a given FM signal was much shorter; thus its market was more local than for AM radio. The reception range at night is the same as in the daytime. All FM broadcast transmissions are line-of-sight, and ionospheric bounce is not viable. The much larger bandwidths, compared to AM and SSB, are more susceptible to phase dispersion. Propagation speeds (celerities) are fastest in the ionosphere at the lowest sideband frequency. The celerity difference between the highest and lowest sidebands is quite apparent to the listener. Such distortion occurs up to frequencies of approximately 50 MHz. Higher frequencies do not reflect from the ionosphere, nor from storm clouds. Moon reflections have been used in some experiments, but require impractical power levels.
The original FM radio service in the U.S. was the Yankee Network, located in New England. Regular FM broadcasting began in 1939 but did not pose a significant threat to the AM broadcasting industry. It required purchase of a special receiver. The frequencies used, 42 to 50 MHz, were not those used today. The change to the current frequencies, 88 to 108 MHz, began after the end of World War II and was to some extent imposed by AM broadcasters as an attempt to cripple what was by now realized to be a potentially serious threat.
FM radio on the new band had to begin from the ground floor. As a commercial venture, it remained a little-used audio enthusiasts' medium until the 1960s. The more prosperous AM stations, or their owners, acquired FM licenses and often broadcast the same programming on the FM station as on the AM station ("simulcasting"). The FCC limited this practice in the 1960s. By the 1980s, since almost all new radios included both AM and FM tuners, FM became the dominant medium, especially in cities. Because of its greater range, AM remained more common in rural environments.
Pirate radio is illegal or non-regulated radio transmission. It is most commonly used to describe illegal broadcasting for entertainment or political purposes. Sometimes it is used for illegal two-way radio operation. Its history can be traced back to the unlicensed nature of the transmission, but historically there has been occasional use of sea vessels—fitting the most common perception of a pirate—as broadcasting bases. Rules and regulations vary largely from country to country, but often the term pirate radio generally describes the unlicensed broadcast of FM radio, AM radio, or shortwave signals over a wide range. In some places, radio stations are legal where the signal is transmitted, but illegal where the signals are received—especially when the signals cross a national boundary. In other cases, a broadcast may be considered "pirate" due to the type of content, its transmission format, or the transmitting power (wattage) of the station, even if the transmission is not technically illegal (such as a webcast or an amateur radio transmission). Pirate radio stations are sometimes referred to as bootleg radio or clandestine stations.
Digital radio broadcasting has emerged, first in Europe (the UK in 1995 and Germany in 1999), and later in the United States, France, the Netherlands, South Africa, and many other countries worldwide. The most simple system is named DAB Digital Radio, for Digital Audio Broadcasting, and uses the public domain EUREKA 147 (Band III) system. DAB is used mainly in the UK and South Africa. Germany and the Netherlands use the DAB and DAB+ systems, and France uses the L-Band system of DAB Digital Radio.
In the United States, digital radio isn't used in the same way as Europe and South Africa. Instead, the IBOC system is named HD Radio and owned by a consortium of private companies that is called iBiquity. An international non-profit consortium Digital Radio Mondiale (DRM), has introduced the public domain DRM system.
Extensions of traditional radio-wave broadcasting for audio broadcasting in general include cable radio, local wire television networks, DTV radio, satellite radio, and internet radio via streaming media on the Internet.
The enormous entry costs of space-based satellite transmitters and restrictions on available radio spectrum licenses has restricted growth of Satellite radio broadcasts. In the USA and Canada, just two services, XM Satellite Radio and Sirius Satellite Radio exist. Both XM and Sirius are owned by Sirius XM Satellite Radio, which was formed by the merger of XM and Sirius on July 29, 2008, whereas in Canada, XM Radio Canada and Sirius Canada remained separate companies until 2010. Worldspace in Africa and Asia, and MobaHO! in Japan and the ROK were two unsuccessful satellite radio operators which have gone out of business.
Radio program formats differ by country, regulation, and markets. For instance, the U.S. Federal Communications Commission designates the 88–92 megahertz band in the U.S. for non-profit or educational programming, with advertising prohibited.
In addition, formats change in popularity as time passes and technology improves. Early radio equipment only allowed program material to be broadcast in real time, known as live broadcasting. As technology for sound recording improved, an increasing proportion of broadcast programming used pre-recorded material. A current trend is the automation of radio stations. Some stations now operate without direct human intervention by using entirely pre-recorded material sequenced by computer control.
The All-Russia State Television and Radio Broadcasting Company (Russian: Всероссийская государственная телевизионная и радиовещательная компания, Vserossiyskaya Gosudarstvennaya Televizionnaya i Radioveshchatelnaya Kompaniya), in short VGTRK (Russian: ВГТРК) which operates a large number of television and radio channels in 53 of Russia's languages. The company was founded in 1990 and is based in Moscow.The broadcasting of the All-Russia TV and radio channels is located in Moscow, and also via the regional transmitting centres of the Russian Television and Radio Broadcasting Network forming the terrestrial transmitting network. TV and radio channels from Moscow are delivered to the regions via satellite and terrestrial communication channels.CJBC (AM)
CJBC is a Canadian Class A clear-channel station, which broadcasts at 860 AM in Toronto, Ontario. It is the city's affiliate of the Ici Radio-Canada Première network. CJBC's studios are located at the Canadian Broadcasting Centre, while its transmitter is located in Hornby.Canadian Radio Broadcasting Commission
The Canadian Radio Broadcasting Commission (CRBC) was Canada's first public broadcaster and the immediate precursor to the Canadian Broadcasting Corporation.Educational Media Foundation
Educational Media Foundation (formerly EMF Broadcasting, abbreviated EMF) is an American nonprofit organization that operates radio networks broadcasting contemporary Christian music, including Air1 and K-Love. EMF is based in Rocklin, California, a suburb of Sacramento, California.
As of 2018, EMF directly owns and operates at least 415 radio stations throughout the United States. The programming for Air1 and K-Love is distributed by satellite and carried on its own stations, including a large number of low-power FM translators and some stations which it operates on behalf of other owners.
EMF's President and CEO Mike Novak was named to those positions on October 1, 2007, succeeding Dick Jenkins, the network's founder. On June 1, 2018, Novak announced that he would retire from EMF within the next several months after 20 years of service to the organization. He would remain on board until his successor is named.The K-Love Air1 Foundation operates as a fundraising arm of EMF.Emmis Communications
Emmis Communications is an American media conglomerate based in Indianapolis, Indiana. The company owns radio stations and magazines in the United States and Slovakia.FM broadcasting
FM broadcasting is a method of radio broadcasting using frequency modulation (FM) technology. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high-fidelity sound over broadcast radio. FM broadcasting is capable of better sound quality than AM broadcasting (under normal listening conditions), the chief competing radio broadcasting technology, so it is used for most music broadcasts. Theoretically wideband AM can offer equally good sound quality, provided the reception conditions are ideal. FM radio stations use the VHF frequencies. The term "FM band" describes the frequency band in a given country which is dedicated to FM broadcasting.NRK
NRK (an abbreviation of the Norwegian: Norsk rikskringkasting AS, generally expressed in English as the Norwegian Broadcasting Corporation) is the Norwegian government-owned radio and television public broadcasting company, and the largest media organisation in Norway. NRK broadcasts three national TV channels and three national radio channels on digital terrestrial television, digital terrestrial radio and subscription television. All NRK radio stations are being streamed online at NRK.no, which also offers an extensive TV service. NRK is a founding member of the European Broadcasting Union.Paley Center for Media
The Paley Center for Media, formerly the Museum of Television & Radio (MT&R) and the Museum of Broadcasting, founded in 1975 by William S. Paley, is an American cultural institution in New York and Los Angeles dedicated to the discussion of the cultural, creative, and social significance of television, radio, and emerging platforms for the professional community and media-interested public.
It was renamed The Paley Center for Media on June 5, 2007, to encompass emerging broadcasting technologies such as the Internet, mobile video, and podcasting, as well as to expand its role as a neutral setting where media professionals can engage in discussion and debate about the evolving media landscape.Philippine Daily Inquirer
The Philippine Daily Inquirer, popularly known as the Inquirer, is an English-language newspaper in the Philippines. Founded in 1985, it is often regarded as the Philippines' newspaper of record.Radio network
There are two types of radio network currently in use around the world: the one-to-many (simplex communication) broadcast network commonly used for public information and mass-media entertainment, and the two-way radio (duplex communication) type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery services. Cell phones are able to send and receive simultaneously by using two different frequencies at the same time. Many of the same components and much of the same basic technology applies to all three.
The two-way type of radio network shares many of the same technologies and components as the broadcast-type radio network but is generally set up with fixed broadcast points (transmitters) with co-located receivers and mobile receivers/transmitters or transceivers. In this way both the fixed and mobile radio units can communicate with each other over broad geographic regions ranging in size from small single cities to entire states/provinces or countries. There are many ways in which multiple fixed transmit/receive sites can be interconnected to achieve the range of coverage required by the jurisdiction or authority implementing the system: conventional wireless links in numerous frequency bands, fibre-optic links, or microwave links. In all of these cases the signals are typically backhauled to a central switch of some type where the radio message is processed and resent (repeated) to all transmitter sites where it is required to be heard.
In contemporary two-way radio systems a concept called trunking is commonly used to achieve better efficiency of radio spectrum use and provide very wide-ranging coverage with no switching of channels required by the mobile radio user as it roams throughout the system coverage. Trunking of two-way radio is identical to the concept used for cellular phone systems where each fixed and mobile radio is specifically identified to the system controller and its operation is switched by the controller.Rogers Media
Rogers Media, Inc. is a subsidiary of Rogers Communications, which owns Canada's largest publishing company, Rogers Publishing Limited, which has more than 70 consumer and business publications. Rogers Media Inc. also owns 52 radio stations, and several television properties including terrestrial television stations and cable television channels.Rogers Radio
Rogers Radio is a subdivision of Rogers Communications, a division of Rogers Media, specializing in the radio broadcasting industry. Rogers Radio is Canada's third-largest radio broadcaster (after Bell Media Radio & Stingray Digital) and the largest based in Ontario.
As of January 2015, the company owns and operates 52 radio stations (44 FM and 8 AM) in Alberta, British Columbia, Manitoba, Nova Scotia and Ontario.Romanian Radio Broadcasting Company
The Romanian Radio Broadcasting Company (Romanian: Societatea Română de Radiodifuziune), informally referred to as Radio Romania (Romanian: Radio România), is the public radio broadcaster in Romania. It operates FM and AM, and internet national and local radio channels. The local stations are branded under the Radio România Regional umbrella. Radio Romania International is the company's international radio station, broadcasting on two channels in Romanian, English, French, Aromanian, Spanish, German, Italian, Serbian, Russian, Ukrainian, Chinese, and Arabic.Russian Television and Radio Broadcasting Network
Russian Television and Radio Broadcasting Network (RTRS) (Russian: Российская телевизионная и радиовещательная сеть) is a unitary enterprise that was created on August 13, 2001, by decree of president Vladimir Putin. RTRS owns 14,478 television transmitters (90.9% of the total number) and 3,697 radio transmitters (89.6% of the total number).On the "Broadband Russia" Forum of 2013, RTRS announced its willingness to join the target program for the development of broadband access in Russia up to 2018. According to RTRS Deputy Director of Engineering and Technical Support Sergei Alyabyev, the company wants to help operators provide the population of small towns and villages with quality Internet access. The company is ready to provide market players under construction in 25 regions of radio relay IP-based network access at speeds up to 300 Mbit/s.Susquehanna Radio Corporation
The Susquehanna Radio Corporation was a media corporation which operated from 1941 to 2006 that was headquartered in York, Pennsylvania. The company was a unit of Susquehanna Pfaltzgraff, a conglomerate more widely known for the Pfaltzgraff kitchenware line than its broadcasting pursuits.
Some of the early Susquehanna radio properties included top 40 music stations WSBA (910 AM) in York, WARM (590 AM) in Scranton, Pennsylvania, WICE (1290 AM, now WRPA) in Providence, Rhode Island, and WHLO (640 AM) in Akron, Ohio. WQBA (1140 AM), a Spanish-language station in Miami, Florida, was also part of the group. Susquehanna's best-known acquisition was the 1989 purchase of San Francisco's KNBR (680 AM) from NBC (the last radio station owned by the network) and its shepherding of that station into one of the nation's more well known sports talk stations.
Over time, Susquehanna repositioned itself from a company based largely in the Northeast to one based largely in the Southern and Midwestern markets (nevertheless keeping its original stations in York). The company was absorbed into Cumulus Media in 2006 when Louis Appell's children broke up Susquehanna Pfaltzgraff.
Today, the company is still active as a holding subsidiary named "Radio License Holding SRC, LLC".The Times Group
Bennett Coleman and Company Limited, commonly known as The Times Group, is India’s largest media conglomerate, according to Financial Times as of March 2015. The Audit Bureau of Circulations reported in May 2014 that the Times of India had the largest circulation of any English-language newspaper in the world, with 3,321,702 average qualifying sales. The company remains a family-owned business as the descendants of Sahu Jain own a majority stake in The Times Group. The Times Group has over 11,000 employees and revenue exceeding $1.5 billion.Townsquare Media
Townsquare Media, Inc. (formerly Regent Communications until 2010) is an American radio network and media company based in Greenwich, Connecticut. The company started in radio and expanded into digital media toward the end of the 2000s, starting with the acquisition of the MOG Music Network. As of 2018, Townsquare was the third-largest AM–FM operator in the country, owning over 320 radio stations in 66 markets.WTTM
WTTM (1680 AM, "La Unika") is a radio station broadcasting a Latin Music/Spanish Talk format to the Philadelphia metropolitan area. The station has its studios and offices in Philadelphia and its transmitter site in Cherry Hill, New Jersey. The station is owned by Multicultural Radio Broadcasting, Inc and licensed to Multicultural Radio Broadcasting Licensee, LLC.Your Network of Praise
Your Network of Praise is a non-profit, listener supported, Christian broadcast radio network in the Northern United States, mainly in the state of Montana, but also in nearby states. Based in Havre, Montana, it broadcasts a mix of music and various Christian programs from a variety of sources. The original station, KXEI in Havre, started broadcasting in 1983.