Digital audio is a representation of sound recorded in, or converted into, digital form . In digital audio, the sound wave of the audio signal is typically encoded as numerical samples in a continuous sequence. For example, in CD audio , samples are taken 44,100 times per second , each with 16-bit resolution . Digital audio is also the name for the entire technology of sound recording and reproduction using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s and 1980s, it gradually replaced analog audio technology in many areas of audio engineering , record production and telecommunications in the 1990s and 2000s.
74-691: Faze FM Radio Ltd was the owner of two dance music radio stations in the North of England. It operated Kiss 102 in Manchester and Kiss 105 in Yorkshire from 1994 to 1997 before being taken over by Chrysalis Group . Faze FM Radio Ltd was incorporated in 1993 by Eugene Perera's Level Broadcast Ltd. A licence application for the Manchester ILR with shareholders Level Broadcast , Mike Powell's UKRD , Eastern Counties Newspaper Group and 3i
148-422: A data compression algorithm. Adaptive DPCM (ADPCM) was introduced by P. Cummiskey, Nikil S. Jayant and James L. Flanagan at Bell Labs in 1973. Perceptual coding was first used for speech coding compression, with linear predictive coding (LPC). Initial concepts for LPC date back to the work of Fumitada Itakura ( Nagoya University ) and Shuzo Saito ( Nippon Telegraph and Telephone ) in 1966. During
222-462: A digital system do not result in error unless they are so large as to result in a symbol being misinterpreted as another symbol or disturbing the sequence of symbols. It is, therefore, generally possible to have an entirely error-free digital audio system in which no noise or distortion is introduced between conversion to digital format and conversion back to analog. A digital audio signal may be encoded for correction of any errors that might occur in
296-486: A digital-to-analog converter (DAC) performs the reverse process, converting a digital signal back into an analog signal, which is then sent through an audio power amplifier and ultimately to a loudspeaker . Digital audio systems may include compression , storage , processing , and transmission components. Conversion to a digital format allows convenient manipulation, storage, transmission, and retrieval of an audio signal. Unlike analog audio, in which making copies of
370-780: A radio network that provides content in a common radio format , either in broadcast syndication or simulcast , or both. The encoding of a radio broadcast depends on whether it uses an analog or digital signal . Analog radio broadcasts use one of two types of radio wave modulation : amplitude modulation for AM radio , or frequency modulation for FM radio . Newer, digital radio stations transmit in several different digital audio standards, such as DAB ( Digital Audio Broadcasting ), HD radio , or DRM ( Digital Radio Mondiale ). The earliest radio stations were radiotelegraphy systems and did not carry audio. For audio broadcasts to be possible, electronic detection and amplification devices had to be incorporated. The thermionic valve ,
444-427: 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 ,
518-489: A DAC. According to the Nyquist–Shannon sampling theorem , with some practical and theoretical restrictions, a band-limited version of the original analog signal can be accurately reconstructed from the digital signal. During conversion, audio data can be embedded with a digital watermark to prevent piracy and unauthorized use. Watermarking is done using a direct-sequence spread-spectrum (DSSS) method. The audio information
592-494: A business opportunity to sell advertising or subscriptions to a broader audience. This is more efficient than broadcasting to a single country, because domestic entertainment programs and information gathered by domestic news staff can be cheaply repackaged for non-domestic audiences. Governments typically have different motivations for funding international broadcasting. One clear reason is for ideological, or propaganda reasons. Many government-owned stations portray their nation in
666-537: A different sampling rate to a common sampling rate prior to processing. Audio data compression techniques, such as MP3 , Advanced Audio Coding (AAC), Opus , Ogg Vorbis , or FLAC , are commonly employed to reduce the file size. Digital audio can be carried over digital audio interfaces such as AES3 or MADI . Digital audio can be carried over a network using audio over Ethernet , audio over IP or other streaming media standards and systems. For playback, digital audio must be converted back to an analog signal with
740-463: A kind of vacuum tube , was invented in 1904 by the English physicist John Ambrose Fleming . He developed a device that 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
814-546: 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
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#1732790131609888-592: 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
962-426: A positive, non-threatening way. This could be to encourage business investment in or tourism to the nation. Another reason is to combat a negative image produced by other nations or internal dissidents, or insurgents. Radio RSA , the broadcasting arm of the apartheid South African government, is an example of this. A third reason is to promote the ideology of the broadcaster. For example, a program on Radio Moscow from
1036-522: A range of digital transmission applications such as the integrated services digital network (ISDN), cordless telephones and cell phones . Digital audio is used in broadcasting of audio. Standard technologies include Digital audio broadcasting (DAB), Digital Radio Mondiale (DRM), HD Radio and In-band on-channel (IBOC). Digital audio in recording applications is stored on audio-specific technologies including CD, DAT, Digital Compact Cassette (DCC) and MiniDisc . Digital audio may be stored in
1110-580: A recording results in generation loss and degradation of signal quality, digital audio allows an infinite number of copies to be made without any degradation of signal quality. Digital audio technologies are used in the recording, manipulation, mass-production, and distribution of sound, including recordings of songs , instrumental pieces, podcasts , sound effects, and other sounds. Modern online music distribution depends on digital recording and data compression . The availability of music as data files, rather than as physical objects, has significantly reduced
1184-460: 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
1258-521: A similar function with Hi8 tapes. Formats like ProDigi and DASH were referred to as SDAT (stationary-head digital audio tape) formats, as opposed to formats like the PCM adaptor-based systems and Digital Audio Tape (DAT), which were referred to as RDAT (rotating-head digital audio tape) formats, due to their helical-scan process of recording. Like the DAT cassette, ProDigi and DASH machines also accommodated
1332-442: A specified sampling rate and converts at a known bit resolution. CD audio , for example, has a sampling rate of 44.1 kHz (44,100 samples per second), and has 16-bit resolution for each stereo channel. Analog signals that have not already been bandlimited must be passed through an anti-aliasing filter before conversion, to prevent the aliasing distortion that is caused by audio signals with frequencies higher than
1406-426: 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
1480-421: Is little affected by daily changes in the ionosphere, so broadcasters need not reduce power at night to avoid interference with other transmitters. 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
1554-439: Is reversed for reproduction: the electrical audio signal is amplified and then converted back into physical waveforms via a loudspeaker . Analog audio retains its fundamental wave-like characteristics throughout its storage, transformation, duplication, and amplification. Analog audio signals are susceptible to noise and distortion, due to the innate characteristics of electronic circuits and associated devices. Disturbances in
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#17327901316091628-472: 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
1702-453: 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
1776-557: Is the automation of radio stations. Some stations now operate without direct human intervention by using entirely pre-recorded material sequenced by computer control. Digital audio In a digital audio system, an analog electrical signal representing the sound is converted with an analog-to-digital converter (ADC) into a digital signal, typically using pulse-code modulation (PCM). This digital signal can then be recorded, edited, modified, and copied using computers , audio playback machines, and other digital tools. For playback,
1850-515: 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
1924-469: Is then modulated by a pseudo-noise (PN) sequence, then shaped within the frequency domain and put back in the original signal. The strength of the embedding determines the strength of the watermark on the audio data. Pulse-code modulation (PCM) was invented by British scientist Alec Reeves in 1937. In 1950, C. Chapin Cutler of Bell Labs filed the patent on differential pulse-code modulation (DPCM),
1998-447: 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,
2072-570: 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 June 15, 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
2146-552: The Nyquist frequency (half the sampling rate). A digital audio signal may be stored or transmitted. Digital audio can be stored on a CD, a digital audio player , a hard drive , a USB flash drive , or any other digital data storage device . The digital signal may be altered through digital signal processing , where it may be filtered or have effects applied. Sample-rate conversion including upsampling and downsampling may be used to change signals that have been encoded with
2220-720: The United States was made by Thomas Stockham at the Santa Fe Opera in 1976, on a Soundstream recorder. An improved version of the Soundstream system was used to produce several classical recordings by Telarc in 1978. The 3M digital multitrack recorder in development at the time was based on BBC technology. The first all-digital album recorded on this machine was Ry Cooder 's Bop till You Drop in 1979. British record label Decca began development of its own 2-track digital audio recorders in 1978 and released
2294-516: The medium wave frequency range of 525 to 1,705 kHz (known as the "standard broadcast band"). The band was expanded in the 1990s by adding nine channels from 1,605 to 1,705 kHz. Channels are spaced every 10 kHz in the Americas , and generally every 9 kHz everywhere else. AM transmissions cannot be ionospheric propagated during the day due to strong absorption in the D-layer of
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2368-702: The 1960s to the 1980s was What is Communism? A second reason is to advance a nation's foreign policy interests and agenda by disseminating its views on international affairs or on the events in particular parts of the world. During the Cold War the American Radio Free Europe and Radio Liberty and Indian Radio AIR were founded to broadcast news from "behind the Iron Curtain " that was otherwise being censored and promote dissent and occasionally, to disseminate disinformation . Currently,
2442-434: The 1970s, Bishnu S. Atal and Manfred R. Schroeder at Bell Labs developed a form of LPC called adaptive predictive coding (APC), a perceptual coding algorithm that exploited the masking properties of the human ear, followed in the early 1980s with the code-excited linear prediction (CELP) algorithm. Discrete cosine transform (DCT) coding, a lossy compression method first proposed by Nasir Ahmed in 1972, provided
2516-593: The 76 to 90 MHz frequency band. Edwin Howard Armstrong invented wide-band FM radio in the early 1930s 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
2590-506: 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
2664-759: The US 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,
2738-580: The US operates similar services aimed at Cuba ( Radio y Televisión Martí ) and the People's Republic of China , Vietnam , Laos and North Korea ( Radio Free Asia ). Besides ideological reasons, many stations are run by religious broadcasters and are used to provide religious education, religious music, or worship service programs. For example, Vatican Radio , established in 1931, broadcasts such programs. Another station, such as HCJB or Trans World Radio will carry brokered programming from evangelists. In
2812-691: The United States and Canada have chosen to use HD radio , an in-band on-channel system that puts digital broadcasts at frequencies adjacent to the analog broadcast. HD Radio is 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, which is used by a relatively small number of broadcasters worldwide. Broadcasters in one country have several reasons to reach out to an audience in other countries. Commercial broadcasters may simply see
2886-589: 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
2960-643: The United States, France, the Netherlands, South Africa, and many other countries worldwide. The simplest 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. The broadcasting regulators of
3034-490: The audio data being recorded to the tape using a multi-track stationary tape head. PCM adaptors allowed for stereo digital audio recording on a conventional NTSC or PAL video tape recorder . The 1982 introduction of the CD by Philips and Sony popularized digital audio with consumers. ADAT became available in the early 1990s, which allowed eight-track 44.1 or 48 kHz recording on S-VHS cassettes, and DTRS performed
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3108-466: The basis for the modified discrete cosine transform (MDCT), which was developed by J. P. Princen, A. W. Johnson and A. B. Bradley in 1987. The MDCT is the basis for most audio coding standards , such as Dolby Digital (AC-3), MP3 ( MPEG Layer III), AAC, Windows Media Audio (WMA), Opus and Vorbis ( Ogg ). PCM was used in telecommunications applications long before its first use in commercial broadcast and recording. Commercial digital recording
3182-728: The case of the Broadcasting Services of the Kingdom of Saudi Arabia , both governmental and religious programming is provided. 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
3256-722: The college teamed up with WLOE in Boston to have students broadcast programs. By 1931, a majority of U.S. households owned at least one radio receiver . 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
3330-714: The company and the Carver Corporation later cut the number of models produced before discontinuing production completely. As well as on the medium wave bands, amplitude modulation (AM) is also used on the shortwave and long wave bands. Shortwave is used largely for national broadcasters, international propaganda, or religious broadcasting organizations. Shortwave transmissions can have international or inter-continental range depending on atmospheric conditions. Long-wave AM broadcasting occurs in Europe, Asia, and Africa. The ground wave propagation at these frequencies
3404-482: The computer can effectively run at a single time. Avid Audio and Steinberg released the first digital audio workstation software programs in 1989. Digital audio workstations make multitrack recording and mixing much easier for large projects which would otherwise be difficult with analog equipment. The rapid development and wide adoption of PCM digital telephony was enabled by metal–oxide–semiconductor (MOS) switched capacitor (SC) circuit technology, developed in
3478-535: The costs of distribution as well as making it easier to share copies. Before digital audio, the music industry distributed and sold music by selling physical copies in the form of records and cassette tapes . With digital audio and online distribution systems such as iTunes , companies sell digital sound files to consumers, which the consumer receives over the Internet. Popular streaming services such as Apple Music , Spotify , or YouTube , offer temporary access to
3552-467: 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
3626-399: The digital file, and are now the most common form of music consumption. An analog audio system converts physical waveforms of sound into electrical representations of those waveforms by use of a transducer , such as a microphone . The sounds are then stored on an analog medium such as magnetic tape , or transmitted through an analog medium such as a telephone line or radio . The process
3700-486: 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
3774-570: The early 1970s. This led to the development of PCM codec-filter chips in the late 1970s. The silicon-gate CMOS (complementary MOS) PCM codec-filter chip, developed by David A. Hodges and W.C. Black in 1980, has since been the industry standard for digital telephony. By the 1990s, telecommunication networks such as the public switched telephone network (PSTN) had been largely digitized with VLSI (very large-scale integration ) CMOS PCM codec-filters, widely used in electronic switching systems for telephone exchanges , user-end modems and
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#17327901316093848-399: The first European digital recording in 1979. Popular professional digital multitrack recorders produced by Sony/Studer ( DASH ) and Mitsubishi ( ProDigi ) in the early 1980s helped to bring about digital recording's acceptance by the major record companies. Machines for these formats had their own transports built-in as well, using reel-to-reel tape in either 1/4", 1/2", or 1" widths, with
3922-583: 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
3996-474: 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
4070-402: 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 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
4144-489: 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
4218-578: The obligatory 44.1 kHz sampling rate, but also 48 kHz on all machines, and eventually a 96 kHz sampling rate. They overcame the problems that made typical analog recorders unable to meet the bandwidth (frequency range) demands of digital recording by a combination of higher tape speeds, narrower head gaps used in combination with metal-formulation tapes, and the spreading of data across multiple parallel tracks. Unlike analog systems, modern digital audio workstations and audio interfaces allow as many channels in as many different sampling rates as
4292-482: The purchase, and in 2011 Global Radio re-branded them both Capital Manchester and Capital Yorkshire as part of the new Capital network. Faze licensed the "Kiss" brand from Kiss 100 in London and commissioned radio ident company Alfasound to make their jingles. Two custom packages were made, the first was called "Danceman" and the follow-up was called "Music is Life". Radio station Radio broadcasting
4366-455: 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 are fastest in the ionosphere at the lowest sideband frequency. The celerity difference between
4440-475: 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, an amplifier
4514-410: 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
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#17327901316094588-533: The station achieved a 10% share of the total available audience, and its yellow oblong car stickers could be seen proudly displayed by an enthusiastic audience across the entire region. Following approaches by most of the country's key media players, Faze FM was purchased by the Chrysalis Group (now Global Radio ) for £17.6m just over four years after the company had been founded with an initial investment of £600k. The stations were renamed as Galaxy after
4662-534: 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 the United States. The commercial broadcasting designation came from the type of broadcast license ; advertisements did not air until years later. The first licensed broadcast in
4736-400: The storage or transmission of the signal. This technique, known as channel coding , is essential for broadcast or recorded digital systems to maintain bit accuracy. Eight-to-fourteen modulation is the channel code used for the audio compact disc (CD). If an audio signal is analog, a digital audio system starts with an ADC that converts an analog signal to a digital signal. The ADC runs at
4810-408: 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
4884-505: 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
4958-530: Was amalgamated in 1922 and received a Royal Charter in 1926, making it the first national broadcaster in the world, followed by Czechoslovak 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
5032-513: 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,
5106-460: 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
5180-447: Was pioneered in Japan by NHK and Nippon Columbia and their Denon brand, in the 1960s. The first commercial digital recordings were released in 1971. The BBC also began to experiment with digital audio in the 1960s. By the early 1970s, it had developed a 2-channel recorder, and in 1972 it deployed a digital audio transmission system that linked their broadcast center to their remote transmitters. The first 16-bit PCM recording in
5254-537: 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
5328-494: Was still required. The triode (mercury-vapor filled with a control grid) was created on March 4, 1906, by the Austrian Robert von Lieben ; independently, on October 25, 1906, Lee De Forest patented his three-element Audion . It was not 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
5402-687: Was successful and Faze FM Radio Ltd launched as Kiss 102 in November 1994. At launch, Guy Hornsby was Managing Director, Mike Gray, Programme Controller, Julian Martin, Sales Controller and Eugene Perera, Marketing Director. A further successful licence application for the Yorkshire regional licence resulted in the launch of Kiss 105 in 1997. Initially the group employed just 17 staff, but this grew to over 120 individuals working full and part-time in programming, sales, marketing, administration, finance and engineering. The Kiss 102/105 dance music format
5476-424: Was the brainchild of two highly experienced UK radio programmers, Mike Gray and Guy Hornsby, who first worked together at the original BBC Radio London where they produced the station's leading DJ presenters Robbie Vincent and Tony Blackburn . Despite staying true to its roots and playing "thumping dance music " at breakfast time, a move perceived of in the radio industry at the time as unlikely to be popular,
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