FM broadcasting is a method of radio broadcasting that uses frequency modulation ( FM ) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong , wide-band FM is used worldwide to transmit high-fidelity sound over broadcast radio . FM broadcasting offers higher fidelity—more accurate reproduction of the original program sound—than other broadcasting techniques, such as AM broadcasting . It is also less susceptible to common forms of interference , having less static and popping sounds than are often heard on AM. Therefore, FM is used for most broadcasts of music and general audio (in the audio spectrum). FM radio stations use the very high frequency range of radio frequencies .
163-663: WKCR-FM (89.9 FM ) is a radio station licensed to New York, New York . The station is owned by Columbia University and serves the New York metropolitan area . Founded in 1941, the station traces its history back to 1908 with the first operations of the Columbia University Radio Club (CURC). In 1956, it became one of the first college radio stations to adopt FM broadcasting , which had been invented two decades earlier by Professor Edwin Howard Armstrong . The station
326-639: A 23‑year‑old student, had begun frequenting and recording performances at Minton's Playhouse , where Monk was the house pianist, in 1940 after being introduced by bassist and vocalist Duke Groner . The 23 acetate disc recordings he made over 1941 constitute the earliest recordings ever made of Monk's playing. The broadcast recording was made by Newman and several CURC members on one afternoon, with Newman and another student alternating as master of ceremonies . Four sets were recorded featuring Monk, Don Byas , Joe Guy , Kenny Clarke , and Helen Humes , and were rushed back to Columbia and played on CURC in
489-399: A 500 kHz frequency separation even when closer frequency spacing is technically permitted. The ITU publishes Protection Ratio graphs, which give the minimum spacing between frequencies based on their relative strengths. Only broadcast stations with large enough geographic separations between their coverage areas can operate on the same or close frequencies. Frequency modulation or FM
652-480: A brief appearance to play a duet with Cale on the viola. The blues and jazz record label Oblivion Records was based at the WKCR studio from 1972 until 1976, when it ceased initial operations. The label was founded by staff member Fred Seibert , who would later go on to found MTV , along with Dick Pennington and folk musician Tom Pomposello . During his time at WKCR, Seibert recorded and published live performances made at
815-402: A fax program. The original subcarrier frequency used at KE2XCC was 27.5 kHz. The IF bandwidth was ±5 kHz, as the only goal at the time was to relay AM radio-quality audio. This transmission system used 75 μs audio pre-emphasis like the main monaural audio and subsequently the multiplexed stereo audio. In the late 1950s, several systems to add stereo to FM radio were considered by
978-510: A monophonic broadcast, again the most common permitted maximum deviation is ±75 kHz. However, some countries specify a lower value for monophonic broadcasts, such as ±50 kHz. The bandwidth of an FM transmission is given by the Carson bandwidth rule which is the sum of twice the maximum deviation and twice the maximum modulating frequency. For a transmission that includes RDS this would be 2 × 75 kHz + 2 × 60 kHz = 270 kHz . This
1141-457: A month. However, a day before the station was to install its new antenna, the Port Authority intervened, stating that the antenna was not built to withstand strong enough winds. Despite an earlier agreement that the Port Authority would cover the costs for any transmitter and antenna modification or replacement, when confronted by station officials, the Port Authority refused to pay, denying that
1304-506: A platform for music that was neglected by commercial radio, adopting the slogan "The Alternative". In a time when most Latin programming focused on older music and romantic ballads, it became one of the first stations in the United States to broadcast salsa . It also welcomed experimental and contemporary classical music , featuring musicians including Karlheinz Stockhausen , John Zorn , Zeena Parkins , and John Cage , who, in 1987, used
1467-557: A program feed for AM transmitters of AM/FM stations. SCA subcarriers are typically 67 kHz and 92 kHz. Initially the users of SCA services were private analog audio channels which could be used internally or leased, for example Muzak -type services. There were experiments with quadraphonic sound. If a station does not broadcast in stereo, everything from 23 kHz on up can be used for other services. The guard band around 19 kHz (±4 kHz) must still be maintained, so as not to trigger stereo decoders on receivers. If there
1630-557: A program feed for AM transmitters of AM/FM stations. SCA subcarriers are typically 67 kHz and 92 kHz. Initially the users of SCA services were private analog audio channels which could be used internally or leased, for example Muzak -type services. There were experiments with quadraphonic sound. If a station does not broadcast in stereo, everything from 23 kHz on up can be used for other services. The guard band around 19 kHz (±4 kHz) must still be maintained, so as not to trigger stereo decoders on receivers. If there
1793-400: A show focusing on Charlie Parker that he started in 1981 and hosted every weekday for about forty years. The New Yorker described Bird Flight as "plac[ing] a degree of attention on the music of the bebop saxophonist Charlie Parker that is so obsessive, so ardent and detailed, that Schaap frequently sounds like a mad Talmudic scholar who has decided that the laws of humankind reside not in
SECTION 10
#17330858825301956-877: A single artist's recorded work, in addition to interviews and educational programming. Festival broadcasts generally last 150 hours or longer, and the longest festivals have included the 2000 Louis Armstrong Centennial Festival Part I, which lasted for 184 hours non-stop from June 30 to July 7, and the 1999 Duke Ellington Centennial Festival, which lasted for 240 hours from April 23 to May 1. Musicians that have participated live in their own festivals include Ornette Coleman (February 1975), Roy Eldridge (January 1978), Sonny Rollins (March 1978), Cecil Taylor (March 1979), Max Roach (March 1981), Steve Lacy (November 1981), Benny Carter (August 1982), Eddie Durham (Summer 1986), Sun Ra (April 1987), Dizzy Gillespie (May 1987), Art Blakey (November 1989), Lionel Hampton (May 1990), and Don Cherry (May 1992). In one notable incident, during
2119-417: A stereo/mono switch to allow listening in mono when reception conditions are less than ideal, and most car radios are arranged to reduce the separation as the signal-to-noise ratio worsens, eventually going to mono while still indicating a stereo signal is received. As with monaural transmission, it is normal practice to apply pre-emphasis to the left and right channels before encoding and to apply de-emphasis at
2282-470: A studio-to-transmitter link system. In April 1935, the AM subcarriers were replaced by FM subcarriers, with much improved results. The first FM subcarrier transmissions emanating from Major Armstrong's experimental station KE2XCC at Alpine, New Jersey occurred in 1948. These transmissions consisted of two-channel audio programs, binaural audio programs and a fax program. The original subcarrier frequency used at KE2XCC
2445-408: Is a form of modulation which conveys information by varying the frequency of a carrier wave ; the older amplitude modulation or AM varies the amplitude of the carrier, with its frequency remaining constant. With FM, frequency deviation from the assigned carrier frequency at any instant is directly proportional to the amplitude of the (audio) input signal, determining the instantaneous frequency of
2608-525: Is added. VHF radio waves usually do not travel far beyond the visual horizon , so reception distances for FM stations are typically limited to 30–40 miles (50–60 km). They can also be blocked by hills and to a lesser extent by buildings. Individuals with more-sensitive receivers or specialized antenna systems, or who are located in areas with more favorable topography, may be able to receive useful FM broadcast signals at considerably greater distances. The knife edge effect can permit reception where there
2771-525: Is added. VHF radio waves usually do not travel far beyond the visual horizon , so reception distances for FM stations are typically limited to 30–40 miles (50–60 km). They can also be blocked by hills and to a lesser extent by buildings. Individuals with more-sensitive receivers or specialized antenna systems, or who are located in areas with more favorable topography, may be able to receive useful FM broadcast signals at considerably greater distances. The knife edge effect can permit reception where there
2934-422: Is also known as the necessary bandwidth . Random noise has a triangular spectral distribution in an FM system, with the effect that noise occurs predominantly at the higher audio frequencies within the baseband . This can be offset, to a limited extent, by boosting the high frequencies before transmission and reducing them by a corresponding amount in the receiver. Reducing the high audio frequencies in
3097-408: Is amplitude modulated onto a 38 kHz double-sideband suppressed-carrier (DSB-SC) signal, thus occupying 23 kHz to 53 kHz. A 19 kHz ± 2 Hz pilot tone , at exactly half the 38 kHz sub-carrier frequency and with a precise phase relationship to it, as defined by the formula below, is also generated. The pilot is transmitted at 8–10% of overall modulation level and used by
3260-401: Is as follows: The normal stereo signal can be considered as switching between left and right channels at 38 kHz, appropriately band-limited. The quadraphonic signal can be considered as cycling through LF, LR, RF, RR, at 76 kHz. Early efforts to transmit discrete four-channel quadraphonic music required the use of two FM stations; one transmitting the front audio channels, the other
3423-422: Is authorized for "hybrid" mode operation, wherein both the conventional analog FM carrier and digital sideband subcarriers are transmitted. The output power of an FM broadcasting transmitter is one of the parameters that governs how far a transmission will cover. The other important parameters are the height of the transmitting antenna and the antenna gain . Transmitter powers should be carefully chosen so that
SECTION 20
#17330858825303586-422: Is authorized for "hybrid" mode operation, wherein both the conventional analog FM carrier and digital sideband subcarriers are transmitted. The output power of an FM broadcasting transmitter is one of the parameters that governs how far a transmission will cover. The other important parameters are the height of the transmitting antenna and the antenna gain . Transmitter powers should be carefully chosen so that
3749-506: Is claimed that no difference can be heard with most newer receivers. At present, the FCC rules do not allow this mode of stereo operation. In 1969, Louis Dorren invented the Quadraplex system of single station, discrete, compatible four-channel FM broadcasting. There are two additional subcarriers in the Quadraplex system, supplementing the single one used in standard stereo FM. The baseband layout
3912-503: Is defined by the time constant of a simple RC filter circuit. In most of the world a 50 μs time constant is used. In the Americas and South Korea , 75 μs is used. This applies to both mono and stereo transmissions. For stereo, pre-emphasis is applied to the left and right channels before multiplexing . The use of pre-emphasis becomes a problem because many forms of contemporary music contain more high-frequency energy than
4075-581: Is designed to be capable of use alongside ARI despite using identical subcarrier frequencies. In the United States and Canada , digital radio services are deployed within the FM band rather than using Eureka 147 or the Japanese standard ISDB . This in-band on-channel approach, as do all digital radio techniques, makes use of advanced compressed audio . The proprietary iBiquity system, branded as HD Radio ,
4238-430: Is designed to be capable of use alongside ARI despite using identical subcarrier frequencies. In the United States and Canada , digital radio services are deployed within the FM band rather than using Eureka 147 or the Japanese standard ISDB . This in-band on-channel approach, as do all digital radio techniques, makes use of advanced compressed audio . The proprietary iBiquity system, branded as HD Radio ,
4401-429: Is limited to 30 Hz to 15 kHz to protect a 19 kHz pilot signal. The (L−R) signal, which is also limited to 15 kHz, is amplitude modulated onto a 38 kHz double-sideband suppressed-carrier (DSB-SC) signal, thus occupying 23 kHz to 53 kHz. A 19 kHz ± 2 Hz pilot tone , at exactly half the 38 kHz sub-carrier frequency and with a precise phase relationship to it, as defined by
4564-480: Is mainly the preserve of talk radio, news, sports, religious programming, ethnic (minority language) broadcasting and some types of minority interest music. This shift has transformed AM into the "alternative band" that FM once was. (Some AM stations have begun to simulcast on, or switch to, FM signals to attract younger listeners and aid reception problems in buildings, during thunderstorms, and near high-voltage wires. Some of these stations now emphasize their presence on
4727-480: Is mainly the preserve of talk radio, news, sports, religious programming, ethnic (minority language) broadcasting and some types of minority interest music. This shift has transformed AM into the "alternative band" that FM once was. (Some AM stations have begun to simulcast on, or switch to, FM signals to attract younger listeners and aid reception problems in buildings, during thunderstorms, and near high-voltage wires. Some of these stations now emphasize their presence on
4890-671: Is no direct line of sight between broadcaster and receiver. The reception can vary considerably depending on the position. One example is the Učka mountain range, which makes constant reception of Italian signals from Veneto and Marche possible in a good portion of Rijeka , Croatia, despite the distance being over 200 km (125 miles). Other radio propagation effects such as tropospheric ducting and Sporadic E can occasionally allow distant stations to be intermittently received over very large distances (hundreds of miles), but cannot be relied on for commercial broadcast purposes. Good reception across
5053-625: Is no direct line of sight between broadcaster and receiver. The reception can vary considerably depending on the position. One example is the Učka mountain range, which makes constant reception of Italian signals from Veneto and Marche possible in a good portion of Rijeka , Croatia, despite the distance being over 200 km (125 miles). Other radio propagation effects such as tropospheric ducting and Sporadic E can occasionally allow distant stations to be intermittently received over very large distances (hundreds of miles), but cannot be relied on for commercial broadcast purposes. Good reception across
WKCR-FM - Misplaced Pages Continue
5216-487: Is only suitable for text. A few proprietary systems are used for private communications. A variant of RDS is the North American RBDS or "smart radio" system. In Germany the analog ARI system was used prior to RDS to alert motorists that traffic announcements were broadcast (without disturbing other listeners). Plans to use ARI for other European countries led to the development of RDS as a more powerful system. RDS
5379-425: Is only suitable for text. A few proprietary systems are used for private communications. A variant of RDS is the North American RBDS or "smart radio" system. In Germany the analog ARI system was used prior to RDS to alert motorists that traffic announcements were broadcast (without disturbing other listeners). Plans to use ARI for other European countries led to the development of RDS as a more powerful system. RDS
5542-580: Is open to anyone who does not carry a prohibition and can put up the appropriate licensing and royalty fees. In 2010 around 450 such licences were issued. FM broadcasting FM broadcasting is a method of radio broadcasting that uses frequency modulation ( FM ) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong , wide-band FM is used worldwide to transmit high-fidelity sound over broadcast radio . FM broadcasting offers higher fidelity—more accurate reproduction of
5705-504: Is performed by a decoder, built into stereo receivers. Again, the decoder can use a switching technique to recover the left and right channels. In addition, for a given RF level at the receiver, the signal-to-noise ratio and multipath distortion for the stereo signal will be worse than for the mono receiver. For this reason many stereo FM receivers include a stereo/mono switch to allow listening in mono when reception conditions are less than ideal, and most car radios are arranged to reduce
5868-508: Is related to the transmitter 's RF power, the antenna gain , and antenna height . Interference from other stations is also a factor in some places. In the U.S, the FCC publishes curves that aid in calculation of this maximum distance as a function of signal strength at the receiving location. Computer modelling is more commonly used for this around the world. Many FM stations, especially those located in severe multipath areas, use extra audio compression /processing to keep essential sound above
6031-508: Is related to the transmitter 's RF power, the antenna gain , and antenna height . Interference from other stations is also a factor in some places. In the U.S, the FCC publishes curves that aid in calculation of this maximum distance as a function of signal strength at the receiving location. Computer modelling is more commonly used for this around the world. Many FM stations, especially those located in severe multipath areas, use extra audio compression /processing to keep essential sound above
6194-626: Is stereo, there will typically be a guard band between the upper limit of the DSBSC stereo signal (53 kHz) and the lower limit of any other subcarrier. Digital data services are also available. A 57 kHz subcarrier ( phase locked to the third harmonic of the stereo pilot tone) is used to carry a low-bandwidth digital Radio Data System signal, providing extra features such as station name, alternative frequency (AF), traffic data for satellite navigation systems and radio text (RT). This narrowband signal runs at only 1,187.5 bits per second , thus
6357-578: Is stereo, there will typically be a guard band between the upper limit of the DSBSC stereo signal (53 kHz) and the lower limit of any other subcarrier. Digital data services are also available. A 57 kHz subcarrier ( phase locked to the third harmonic of the stereo pilot tone) is used to carry a low-bandwidth digital Radio Data System signal, providing extra features such as station name, alternative frequency (AF), traffic data for satellite navigation systems and radio text (RT). This narrowband signal runs at only 1,187.5 bits per second , thus
6520-402: Is the sum of twice the maximum deviation and twice the maximum modulating frequency. For a transmission that includes RDS this would be 2 × 75 kHz + 2 × 60 kHz = 270 kHz . This is also known as the necessary bandwidth . Random noise has a triangular spectral distribution in an FM system, with the effect that noise occurs predominantly at the higher audio frequencies within
6683-427: Is used. This applies to both mono and stereo transmissions. For stereo, pre-emphasis is applied to the left and right channels before multiplexing . The use of pre-emphasis becomes a problem because many forms of contemporary music contain more high-frequency energy than the musical styles which prevailed at the birth of FM broadcasting. Pre-emphasizing these high-frequency sounds would cause excessive deviation of
WKCR-FM - Misplaced Pages Continue
6846-664: The Columbia University protests of 1968 , WKCR was the only source of live news from the university. With 50 or 60 students working in shifts, it was able to provide near-nonstop coverage for the week of protests. During the protests, the station had several "special operations" groups—student experts on telephone systems, key collectors who were able to open every lock on campus, and experts in acquiring telephone equipment that, according to station engineer Jon Perelstein, "a college radio station probably shouldn't have had"—which, by breaking into telephone distribution panel rooms through
7009-932: The DuMont Building on Madison Avenue . Following a decade of bureaucratic struggle against the Port Authority of New York and New Jersey and the Federal Communications Commission , it began transmitting from an antenna atop the World Trade Center in 1985. After the towers' destruction in 2001, the station broadcast for a brief period of time from a backup transmitter on the roof of Carman Hall , before moving to 4 Times Square in 2003, where it remains today. Its studios are currently located in Alfred Lerner Hall . The first recorded instance of radio experimentation at Columbia took place in 1906, in
7172-817: The FCC . Included were systems from 14 proponents including Crosby, Halstead, Electrical and Musical Industries, Ltd ( EMI ), Zenith, and General Electric. The individual systems were evaluated for their strengths and weaknesses during field tests in Uniontown, Pennsylvania , using KDKA-FM in Pittsburgh as the originating station. The Crosby system was rejected by the FCC because it was incompatible with existing subsidiary communications authorization (SCA) services which used various subcarrier frequencies including 41 and 67 kHz. Many revenue-starved FM stations used SCAs for "storecasting" and other non-broadcast purposes. The Halstead system
7335-580: The Light Programme , Third Programme and Home Service . These three networks used the sub-band 88.0–94.6 MHz. The sub-band 94.6–97.6 MHz was later used for BBC and local commercial services. However, only when commercial broadcasting was introduced to the UK in 1973 did the use of FM pick up in Britain. With the gradual clearance of other users (notably Public Services such as police, fire and ambulance) and
7498-428: The Light Programme , Third Programme and Home Service . These three networks used the sub-band 88.0–94.6 MHz. The sub-band 94.6–97.6 MHz was later used for BBC and local commercial services. However, only when commercial broadcasting was introduced to the UK in 1973 did the use of FM pick up in Britain. With the gradual clearance of other users (notably Public Services such as police, fire and ambulance) and
7661-535: The Manhattan Municipal Building due to the attacks. WKCR had been planning on moving to Lerner Hall from its temporary studio in Riverside Church before the attacks. In 2011, The New York Times reported that it was considering a move back to the World Trade Center . The station was fined $ 10,000 in 2012 due to a lapse in its record-keeping from 2001 to 2006, which WKCR directors attributed to
7824-477: The SS Miramar . In February 1956, Columbia University applied for a construction permit for a new 10-watt station on 89.9 MHz. The FCC approved on April 5, and the first tests of the new station were carried out on May 14; full-time programming did not begin until October 8 for New York's third noncommercial radio outlet. It used a ten‑watt transmitter that once belonged to Armstrong, which it installed on
7987-440: The baseband . This can be offset, to a limited extent, by boosting the high frequencies before transmission and reducing them by a corresponding amount in the receiver. Reducing the high audio frequencies in the receiver also reduces the high-frequency noise. These processes of boosting and then reducing certain frequencies are known as pre-emphasis and de-emphasis , respectively. The amount of pre-emphasis and de-emphasis used
8150-492: The 1970s and 1980s: A commercially unsuccessful noise reduction system used with FM radio in some countries during the late 1970s, Dolby FM was similar to Dolby B but used a modified 25 μs pre-emphasis time constant and a frequency selective companding arrangement to reduce noise. The pre-emphasis change compensates for the excess treble response that otherwise would make listening difficult for those without Dolby decoders. A similar system named High Com FM
8313-655: The 85th floor of the Empire State Building in New York City . These FM multiplex transmissions started in November 1934 and consisted of the main channel audio program and three subcarriers : a fax program, a synchronizing signal for the fax program and a telegraph order channel. These original FM multiplex subcarriers were amplitude modulated. Two musical programs, consisting of both the Red and Blue Network program feeds of
SECTION 50
#17330858825308476-607: The Americas , the Philippines , and the Caribbean , only odd multiples are used. Some other countries follow this plan because of the import of vehicles, principally from the United States, with radios that can only tune to these frequencies. In some parts of Europe , Greenland , and Africa , only even multiples are used. In the United Kingdom , both odd and even are used. In Italy , multiples of 50 kHz are used. In most countries
8639-638: The FCC announced the reassignment of the FM band to 90 channels from 88–106 MHz (which was soon expanded to 100 channels from 88–108 MHz). This shift, which the AM-broadcaster RCA had pushed for, made all the Armstrong-era FM receivers useless and delayed the expansion of FM. In 1961 WEFM (in the Chicago area) and WGFM (in Schenectady, New York ) were reported as the first stereo stations. By
8802-415: The FCC announced the reassignment of the FM band to 90 channels from 88–106 MHz (which was soon expanded to 100 channels from 88–108 MHz). This shift, which the AM-broadcaster RCA had pushed for, made all the Armstrong-era FM receivers useless and delayed the expansion of FM. In 1961 WEFM (in the Chicago area) and WGFM (in Schenectady, New York ) were reported as the first stereo stations. By
8965-646: The FCC rules do not allow this mode of stereo operation. In 1969, Louis Dorren invented the Quadraplex system of single station, discrete, compatible four-channel FM broadcasting. There are two additional subcarriers in the Quadraplex system, supplementing the single one used in standard stereo FM. The baseband layout is as follows: The normal stereo signal can be considered as switching between left and right channels at 38 kHz, appropriately band-limited. The quadraphonic signal can be considered as cycling through LF, LR, RF, RR, at 76 kHz. Early efforts to transmit discrete four-channel quadraphonic music required
9128-481: The FCC that the system was compatible with existing two-channel stereo transmission and reception and that it did not interfere with adjacent stations. There were several variations on this system submitted by GE, Zenith, RCA, and Denon for testing and consideration during the National Quadraphonic Radio Committee field trials for the FCC. The original Dorren Quadraplex System outperformed all
9291-511: The FCC. The original Dorren Quadraplex System outperformed all the others and was chosen as the national standard for Quadraphonic FM broadcasting in the United States. The first commercial FM station to broadcast quadraphonic program content was WIQB (now called WWWW-FM ) in Ann Arbor / Saline, Michigan under the guidance of Chief Engineer Brian Jeffrey Brown. Various attempts to add analog noise reduction to FM broadcasting were carried out in
9454-451: The FM carrier . Modulation control (limiter) devices are used to prevent this. Systems more modern than FM broadcasting tend to use either programme-dependent variable pre-emphasis; e.g., dbx in the BTSC TV sound system, or none at all. Pre-emphasis and de-emphasis was used in the earliest days of FM broadcasting. According to a BBC report from 1946, 100 μs was originally considered in
9617-511: The FM band.) The medium wave band (known as the AM band because most stations using it employ amplitude modulation) was overcrowded in western Europe, leading to interference problems and, as a result, many MW frequencies are suitable only for speech broadcasting. Belgium , the Netherlands , Denmark and particularly Germany were among the first countries to adopt FM on a widespread scale. Among
9780-414: The FM band.) The medium wave band (known as the AM band because most stations using it employ amplitude modulation) was overcrowded in western Europe, leading to interference problems and, as a result, many MW frequencies are suitable only for speech broadcasting. Belgium , the Netherlands , Denmark and particularly Germany were among the first countries to adopt FM on a widespread scale. Among
9943-917: The FM radio band from 87.5-108.0 MHz to 76.1-108.0 MHz to enable the migration of AM radio stations in Brazilian capitals and large cities. FM broadcasting began in the late 1930s, when it was initiated by a handful of early pioneer experimental stations, including W1XOJ/W43B/WGTR (shut down in 1953) and W1XTG/ WSRS , both transmitting from Paxton, Massachusetts (now listed as Worcester, Massachusetts ); W1XSL/W1XPW/W65H/WDRC-FM/WFMQ/WHCN , Meriden, Connecticut; and W2XMN , KE2XCC , and WFMN , Alpine, New Jersey (owned by Edwin Armstrong himself, closed down upon Armstrong's death in 1954). Also of note were General Electric stations W2XDA Schenectady and W2XOY New Scotland, New York—two experimental FM transmitters on 48.5 MHz—which signed on in 1939. The two began regular programming, as W2XOY, on November 20, 1940. Over
SECTION 60
#173308588253010106-865: The FM radio band from 87.5-108.0 MHz to 76.1-108.0 MHz to enable the migration of AM radio stations in Brazilian capitals and large cities. FM broadcasting began in the late 1930s, when it was initiated by a handful of early pioneer experimental stations, including W1XOJ/W43B/WGTR (shut down in 1953) and W1XTG/ WSRS , both transmitting from Paxton, Massachusetts (now listed as Worcester, Massachusetts ); W1XSL/W1XPW/W65H/WDRC-FM/WFMQ/WHCN , Meriden, Connecticut; and W2XMN , KE2XCC , and WFMN , Alpine, New Jersey (owned by Edwin Armstrong himself, closed down upon Armstrong's death in 1954). Also of note were General Electric stations W2XDA Schenectady and W2XOY New Scotland, New York—two experimental FM transmitters on 48.5 MHz—which signed on in 1939. The two began regular programming, as W2XOY, on November 20, 1940. Over
10269-399: The FM transmitter. The terms composite , multiplex and even MPX are used interchangeably to describe this signal. The instantaneous deviation of the transmitter carrier frequency due to the stereo audio and pilot tone (at 10% modulation) is where A and B are the pre-emphasized left and right audio signals and f p {\displaystyle f_{p}} =19 kHz is
10432-646: The Harvard Wireless Club (W1AF) and the MIT Radio Society (W1MX), it is the oldest amateur radio society. It set up its first experimental station on the roof of University Hall, where Uris Hall now stands, in November of that year with the blessings of Professor Mihajlo Pupin , who donated a corner of his laboratory in Havemeyer Hall to the club, as well a large electromagnetic coil . Originally intended only for catching stray signals from passing ships,
10595-460: The L+R signal so the listener will hear both channels through the single loudspeaker. A stereo receiver will add the difference signal to the sum signal to recover the left channel, and subtract the difference signal from the sum to recover the right channel. The (L+R) signal is limited to 30 Hz to 15 kHz to protect a 19 kHz pilot signal. The (L−R) signal, which is also limited to 15 kHz,
10758-525: The March 1976 festival dedicated to Thelonious Monk, a guest expert was explaining how Monk was able to create extraordinary music by playing "wrong notes" on the piano. Monk, who by this point had become a recluse, called the station and instructed them to "tell the guy on the air, 'The piano ain't got no wrong notes' ", before hanging up. WKCR annually celebrates the birthdays of prominent jazz musicians, including Monk, Louis Armstrong, and Charlie Parker, by playing
10921-534: The NBC Radio Network, were simultaneously transmitted using the same system of subcarrier modulation as part of a studio-to-transmitter link system. In April 1935, the AM subcarriers were replaced by FM subcarriers, with much improved results. The first FM subcarrier transmissions emanating from Major Armstrong's experimental station KE2XCC at Alpine, New Jersey occurred in 1948. These transmissions consisted of two-channel audio programs, binaural audio programs and
11084-527: The Twin Towers. The move was delayed once more until 1981, due to a legal dispute with an unnamed New York‑based station over transmitter interference. WKCR's Madison Avenue transmitter continued to deteriorate until it finally broke down on July 17, 1981. By then, the World Trade Center antenna had already been installed, though the station's FCC permit to finally move had recently expired while it
11247-505: The US, but 75 μs subsequently adopted. Long before FM stereo transmission was considered, FM multiplexing of other types of audio-level information was experimented with. Edwin Armstrong, who invented FM, was the first to experiment with multiplexing, at his experimental 41 MHz station W2XDG located on the 85th floor of the Empire State Building in New York City . These FM multiplex transmissions started in November 1934 and consisted of
11410-399: The United States and became the first North American radio station to rebroadcast this signal. The next morning, two FBI agents walked into the station and confiscated the tape. A Freedom of Information Act request was filed on June 28, 2018, requesting the declassification of all documents related to the confiscation of the tapes and their whereabouts. The request was rejected on account of
11573-633: The United States, having been involved in the New York jazz scene from its founding; one of its first broadcasts was the earliest performance by Thelonious Monk on radio. Through The Stretch Armstrong and Bobbito Show , it has played an instrumental role in the development of hip hop since the 1990s. It was also one of the first stations in the United States to broadcast salsa music . The station made its first AM broadcast out of John Jay Hall and its first FM broadcast from Philosophy Hall , where Armstrong had invented FM. In 1958, it moved its transmitter to
11736-636: The WKCR studios once to remix opera music . During a May 29, 1978, minimalist music marathon hosted by staff member Tim Page , the station presented the radio premiers of several leading minimalist compositions, including Einstein on the Beach by Philip Glass and Music for 18 Musicians by Steve Reich . Page also organized a WKCR charity concert which was held on April 1, 1979, in Carnegie Hall , and featured Glass and Reich, in addition to John Cale , Leroy Jenkins , and Ursula Oppens . David Bowie also made
11899-651: The Wireless Club was known as the Columbia University Radio Club (CURC). The CURC made its first broadcasts with its ham radio station , W2AEE. The call sign was assigned to the CURC as early as 1931 and still operates under the Columbia University Amateur Radio Club. Its first recorded broadcast was in 1933, and the station received its license in 1938. In 1933, FM broadcasting was invented by Professor of Electrical Engineering Edwin Howard Armstrong in
12062-428: The administration relented. The New York Times described WKCR's reporting as "clear and concise with a sound of informality and immediacy". The station contradicted the narratives offered by commercial news outlets, which only broadcast statements made by politicians and university administrators, by offering student perspectives to its audience. When civil rights activists H. Rap Brown and Stokely Carmichael joined
12225-572: The agreement was ever made in the first place. A new antenna, built to the Port Authority's specifications, was constructed in September 1978, and the Port Authority announced that it would grant the station its approval again in a few weeks. In January 1979, WKCR received a $ 43,912 grant from the Office of Education of the United States Department of Health and Human Services to aid in its move to
12388-457: The ancient Babylonian tractates but in alternate takes of ' Moose the Mooche ' and ' Swedish Schnapps .' " The red Naugahyde armchair for visitors in the WKCR studio is named the " Dizzy Gillespie chair", after the trumpeter sat there during an hours-long conversation with Schaap. Beginning in 1970, WKCR has held several jazz festivals a year, each one focusing on the presentation of the entirety of
12551-454: The assigned frequency. There are other unusual and obsolete FM broadcasting standards in some countries, with non-standard spacings of 1, 10, 30, 74, 500, and 300 kHz. To minimise inter-channel interference, stations operating from the same or nearby transmitter sites tend to keep to at least a 500 kHz frequency separation even when closer frequency spacing is technically permitted. The ITU publishes Protection Ratio graphs, which give
12714-511: The background noise for listeners, often at the expense of overall perceived sound quality. In such instances, however, this technique is often surprisingly effective in increasing the station's useful range. The first radio station to broadcast in FM in Brazil was Rádio Imprensa, which began broadcasting in Rio de Janeiro in 1955, on the 102.1 MHz frequency, founded by businesswoman Anna Khoury. Due to
12877-417: The background noise for listeners, often at the expense of overall perceived sound quality. In such instances, however, this technique is often surprisingly effective in increasing the station's useful range. The first radio station to broadcast in FM in Brazil was Rádio Imprensa, which began broadcasting in Rio de Janeiro in 1955, on the 102.1 MHz frequency, founded by businesswoman Anna Khoury. Due to
13040-404: The basement of Philosophy Hall . As an undergraduate at Columbia, he had studied under Pupin and invented the regenerative circuit . Immediately after his graduation in 1913, he was offered a position at the university, and continued his experimentation with radios. In 1914, he strung up another antenna between Havemeyer and Schermerhorn Halls for a new radio. At the time, it was considered "one of
13203-471: The best on the eastern coast", and could reportedly receive signals from as far away as Honolulu , Hawaii. Following his invention of FM, Armstrong created W2XMN , the first regularly operated FM radio station, which made its first broadcast on July 18, 1939. Soon after its completion, the CURC began using W2XMN to test the potential of FM for college radio. The CURC made its first public and FM broadcasts on W2XMN, for which it provided programming. WKCR proper
13366-402: The carrier, with its frequency remaining constant. With FM, frequency deviation from the assigned carrier frequency at any instant is directly proportional to the amplitude of the (audio) input signal, determining the instantaneous frequency of the transmitted signal. Because transmitted FM signals use significantly more bandwidth than AM signals, this form of modulation is commonly used with
13529-431: The country is one of the main advantages over DAB/+ radio . This is still less than the range of AM radio waves, which because of their lower frequencies can travel as ground waves or reflect off the ionosphere , so AM radio stations can be received at hundreds (sometimes thousands) of miles. This is a property of the carrier wave's typical frequency (and power), not its mode of modulation. The range of FM transmission
13692-431: The country is one of the main advantages over DAB/+ radio . This is still less than the range of AM radio waves, which because of their lower frequencies can travel as ground waves or reflect off the ionosphere , so AM radio stations can be received at hundreds (sometimes thousands) of miles. This is a property of the carrier wave's typical frequency (and power), not its mode of modulation. The range of FM transmission
13855-534: The entire catalogue of the artist's work in one broadcast. The station also holds jazz marathons on prominent death anniversaries and other special occasions, such as the beginning of a concert series featuring the Association for the Advancement of Creative Musicians held at Columbia, which the station celebrated with a 90‑hour broadcast starting on May 14, 1977, of the completed recorded works of every member of
14018-408: The evening. The recordings were later released as Midnight at Minton's in 1973. In a review, WEMU broadcaster Michael G. Nastos described the recordings as "priceless, the document of a transitional period from swing to bop". WKCR made the first stereo live broadcast of jazz music in 1960. The performance was by Red Allen 's band, in which J. C. Higginbotham was the trombonist at the time, and
14181-553: The extension of the FM band to 108.0 MHz between 1980 and 1995, FM expanded rapidly throughout the British Isles and effectively took over from LW and MW as the delivery platform of choice for fixed and portable domestic and vehicle-based receivers. In addition, Ofcom (previously the Radio Authority) in the UK issues on demand Restricted Service Licences on FM and also on AM (MW) for short-term local-coverage broadcasting which
14344-439: The extension of the FM band to 108.0 MHz between 1980 and 1995, FM expanded rapidly throughout the British Isles and effectively took over from LW and MW as the delivery platform of choice for fixed and portable domestic and vehicle-based receivers. In addition, Ofcom (previously the Radio Authority) in the UK issues on demand Restricted Service Licences on FM and also on AM (MW) for short-term local-coverage broadcasting which
14507-413: The first station to transmit from the World Trade Center. A nine-day, 200-hour long Louis Armstrong festival was planned to inaugurate the station's new transmitter. The move was delayed again when the Port Authority declared two of the application forms to be incomplete. The applications were resubmitted, and in November, the Port Authority announced that the station would be able to make the move within
14670-475: The formula below, is also generated. The pilot is transmitted at 8–10% of overall modulation level and used by the receiver to identify a stereo transmission and to regenerate the 38 kHz sub-carrier with the correct phase. The composite stereo multiplex signal contains the Main Channel (L+R), the pilot tone, and the (L−R) difference signal. This composite signal, along with any other sub-carriers, modulates
14833-482: The frequency of the pilot tone. Slight variations in the peak deviation may occur in the presence of other subcarriers or because of local regulations. Another way to look at the resulting signal is that it alternates between left and right at 38 kHz, with the phase determined by the 19 kHz pilot signal. Most stereo encoders use this switching technique to generate the 38 kHz subcarrier, but practical encoder designs need to incorporate circuitry to deal with
14996-505: The high import costs of FM radio receivers, transmissions were carried out in circuit closed to businesses and stores, which played ambient music offered by radio. Until 1976, Rádio Imprensa was the only station operating in FM in Brazil. From the second half of the 1970s onwards, FM radio stations began to become popular in Brazil, causing AM radio to gradually lose popularity. In 2021, the Brazilian Ministry of Communications expanded
15159-444: The high import costs of FM radio receivers, transmissions were carried out in circuit closed to businesses and stores, which played ambient music offered by radio. Until 1976, Rádio Imprensa was the only station operating in FM in Brazil. From the second half of the 1970s onwards, FM radio stations began to become popular in Brazil, causing AM radio to gradually lose popularity. In 2021, the Brazilian Ministry of Communications expanded
15322-467: The higher ( VHF or UHF ) frequencies used by TV , the FM broadcast band , and land mobile radio systems . The maximum frequency deviation of the carrier is usually specified and regulated by the licensing authorities in each country. For a stereo broadcast, the maximum permitted carrier deviation is invariably ±75 kHz, although a little higher is permitted in the United States when SCA systems are used. For
15485-440: The import of vehicles, principally from the United States, with radios that can only tune to these frequencies. In some parts of Europe , Greenland , and Africa , only even multiples are used. In the United Kingdom , both odd and even are used. In Italy , multiples of 50 kHz are used. In most countries the maximum permitted frequency error of the unmodulated carrier is specified, which typically should be within 2 kHz of
15648-462: The incident was uploaded to 4chan in 2013. FM broadcasting Throughout the world, the FM broadcast band falls within the VHF part of the radio spectrum . Usually 87.5 to 108.0 MHz is used, or some portion of it, with few exceptions: The frequency of an FM broadcast station (more strictly its assigned nominal center frequency) is usually a multiple of 100 kHz. In most of South Korea ,
15811-517: The late 1960s, FM had been adopted for broadcast of stereo "A.O.R.—' Album Oriented Rock ' Format", but it was not until 1978 that listenership to FM stations exceeded that of AM stations in North America. In most of the 70s FM was seen as highbrow radio associated with educational programming and classical music, which changed during the 1980s and 1990s when Top 40 music stations and later even country music stations largely abandoned AM for FM. Today AM
15974-461: The late 1960s, FM had been adopted for broadcast of stereo "A.O.R.—' Album Oriented Rock ' Format", but it was not until 1978 that listenership to FM stations exceeded that of AM stations in North America. In most of the 70s FM was seen as highbrow radio associated with educational programming and classical music, which changed during the 1980s and 1990s when Top 40 music stations and later even country music stations largely abandoned AM for FM. Today AM
16137-496: The late 1970s, Dolby FM was similar to Dolby B but used a modified 25 μs pre-emphasis time constant and a frequency selective companding arrangement to reduce noise. The pre-emphasis change compensates for the excess treble response that otherwise would make listening difficult for those without Dolby decoders. A similar system named High Com FM was tested in Germany between July 1979 and December 1981 by IRT . It
16300-416: The left (L) and right (R) channels are algebraically encoded into sum (L+R) and difference (L−R) signals. A mono receiver will use just the L+R signal so the listener will hear both channels through the single loudspeaker. A stereo receiver will add the difference signal to the sum signal to recover the left channel, and subtract the difference signal from the sum to recover the right channel. The (L+R) signal
16463-410: The main channel audio program and three subcarriers : a fax program, a synchronizing signal for the fax program and a telegraph order channel. These original FM multiplex subcarriers were amplitude modulated. Two musical programs, consisting of both the Red and Blue Network program feeds of the NBC Radio Network, were simultaneously transmitted using the same system of subcarrier modulation as part of
16626-564: The main channel signal-to-noise ratio. The GE and Zenith systems, so similar that they were considered theoretically identical, were formally approved by the FCC in April 1961 as the standard stereo FM broadcasting method in the United States and later adopted by most other countries. It is important that stereo broadcasts be compatible with mono receivers. For this reason, the left (L) and right (R) channels are algebraically encoded into sum (L+R) and difference (L−R) signals. A mono receiver will use just
16789-428: The maximum permitted carrier deviation is invariably ±75 kHz, although a little higher is permitted in the United States when SCA systems are used. For a monophonic broadcast, again the most common permitted maximum deviation is ±75 kHz. However, some countries specify a lower value for monophonic broadcasts, such as ±50 kHz. The bandwidth of an FM transmission is given by the Carson bandwidth rule which
16952-427: The maximum permitted frequency error of the unmodulated carrier is specified, which typically should be within 2 kHz of the assigned frequency. There are other unusual and obsolete FM broadcasting standards in some countries, with non-standard spacings of 1, 10, 30, 74, 500, and 300 kHz. To minimise inter-channel interference, stations operating from the same or nearby transmitter sites tend to keep to at least
17115-405: The minimum spacing between frequencies based on their relative strengths. Only broadcast stations with large enough geographic separations between their coverage areas can operate on the same or close frequencies. Frequency modulation or FM is a form of modulation which conveys information by varying the frequency of a carrier wave ; the older amplitude modulation or AM varies the amplitude of
17278-420: The musical styles which prevailed at the birth of FM broadcasting. Pre-emphasizing these high-frequency sounds would cause excessive deviation of the FM carrier . Modulation control (limiter) devices are used to prevent this. Systems more modern than FM broadcasting tend to use either programme-dependent variable pre-emphasis; e.g., dbx in the BTSC TV sound system, or none at all. Pre-emphasis and de-emphasis
17441-504: The name CURC, the station made its unofficial debut on December 31, 1940, with a broadcast of audio from a New Year's Eve party in John Jay Dining Hall. Its official maiden broadcast was made on February 24, 1941, and opened with a recording of " Roar, Lion, Roar ", followed by light classical music, a 15‑minute sports show, 40 minutes of jazz, a campus news summary, and symphonic music. The station soon moved its headquarters to
17604-548: The news department would travel to Washington, D.C. annually to interview political figures, while WKCR became the only station in the New York area to carry United Nations General Assembly meetings in full. While the station's musical programming mainly focused on classical, it also played jazz, folk, bluegrass, and show tunes . Guests who were interviewed on the station during this time period included Martin Luther King Jr. , William F. Buckley Jr. , and Jimmy Hoffa . During
17767-536: The next few years this station operated under the call signs W57A, W87A and WGFM, and moved to 99.5 MHz when the FM band was relocated to the 88–108 MHz portion of the radio spectrum. General Electric sold the station in the 1980s. Today this station is WRVE . Other pioneers included W2XQR/W59NY/WQXQ/WQXR-FM , New York; W47NV/WSM-FM Nashville, Tennessee (signed off in 1951); W1XER/W39B/WMNE , with studios in Boston and later Portland, Maine, but whose transmitter
17930-487: The next few years this station operated under the call signs W57A, W87A and WGFM, and moved to 99.5 MHz when the FM band was relocated to the 88–108 MHz portion of the radio spectrum. General Electric sold the station in the 1980s. Today this station is WRVE . Other pioneers included W2XQR/W59NY/WQXQ/WQXR-FM , New York; W47NV/WSM-FM Nashville, Tennessee (signed off in 1951); W1XER/W39B/WMNE , with studios in Boston and later Portland, Maine, but whose transmitter
18093-399: The next sixteen years. From 1990 to 1998, WKCR broadcast The Stretch Armstrong and Bobbito Show , hosted by DJ Stretch Armstrong and Bobbito Garcia . The show served as an alternative to commercial hip hop radio, airing mostly obscure, unsigned artists, a number of whom would later dominate the hip hop scene in the late 1990s and early 2000s. The show has been credited with introducing
18256-403: The organization. Poet and critic Molly McQuade has praised WKCR's jazz programming, stating that "WKCR's inspired programming feels more like dream logic than traditional radio" and that she is "willingly indebted and harmlessly addicted" to several of the station's programs. When Sputnik 1 was launched on October 4, 1957, WKCR staff recorded its signal during the satellite's first pass over
18419-405: The original program sound—than other broadcasting techniques, such as AM broadcasting . It is also less susceptible to common forms of interference , having less static and popping sounds than are often heard on AM. Therefore, FM is used for most broadcasts of music and general audio (in the audio spectrum). FM radio stations use the very high frequency range of radio frequencies . Throughout
18582-433: The originating station. The Crosby system was rejected by the FCC because it was incompatible with existing subsidiary communications authorization (SCA) services which used various subcarrier frequencies including 41 and 67 kHz. Many revenue-starved FM stations used SCAs for "storecasting" and other non-broadcast purposes. The Halstead system was rejected due to lack of high frequency stereo separation and reduction in
18745-514: The others and was chosen as the national standard for Quadraphonic FM broadcasting in the United States. The first commercial FM station to broadcast quadraphonic program content was WIQB (now called WWWW-FM ) in Ann Arbor / Saline, Michigan under the guidance of Chief Engineer Brian Jeffrey Brown. Various attempts to add analog noise reduction to FM broadcasting were carried out in the 1970s and 1980s: A commercially unsuccessful noise reduction system used with FM radio in some countries during
18908-447: The phone on the next desk over and continued his report. Station staff also tapped a New York City Police Department phone line that ran from a university telephone distribution panel to a command vehicle outside, and, on radios loaned from W2AEE, stalked frequencies known to be used by the NYPD when planning large operations. I'm in a room on the seventh floor [of Hartley Hall ] overlooking
19071-419: The protests, they were interviewed on WKCR. Following the station's involvement in the protests, the university administration has treated the station with animosity. After 1968, WKCR sought to rid itself of its reputation as a "classroom of the air". The AM carrier current service was discontinued, while the FM station shifted its emphasis from education to music, particularly jazz. The station sought to provide
19234-500: The rear channels. A breakthrough came in 1970 when KIOI ( K-101 ) in San Francisco successfully transmitted true quadraphonic sound from a single FM station using the Quadraplex system under Special Temporary Authority from the FCC . Following this experiment, a long-term test period was proposed that would permit one FM station in each of the top 25 U.S. radio markets to transmit in Quadraplex. The test results hopefully would prove to
19397-551: The reasons for this were: Public service broadcasters in Ireland and Australia were far slower at adopting FM radio than those in either North America or continental Europe . Hans Idzerda operated a broadcasting station, PCGG , at The Hague from 1919 to 1924, which employed narrow-band FM transmissions. In the United Kingdom the BBC conducted tests during the 1940s, then began FM broadcasting in 1955, with three national networks:
19560-457: The reasons for this were: Public service broadcasters in Ireland and Australia were far slower at adopting FM radio than those in either North America or continental Europe . Hans Idzerda operated a broadcasting station, PCGG , at The Hague from 1919 to 1924, which employed narrow-band FM transmissions. In the United Kingdom the BBC conducted tests during the 1940s, then began FM broadcasting in 1955, with three national networks:
19723-478: The receiver after decoding. In the U.S. around 2010, using single-sideband modulation for the stereo subcarrier was proposed. It was theorized to be more spectrum-efficient and to produce a 4 dB s/n improvement at the receiver, and it was claimed that multipath distortion would be reduced as well. A handful of radio stations around the country broadcast stereo in this way, under FCC experimental authority. It may not be compatible with very old receivers, but it
19886-400: The receiver also reduces the high-frequency noise. These processes of boosting and then reducing certain frequencies are known as pre-emphasis and de-emphasis , respectively. The amount of pre-emphasis and de-emphasis used is defined by the time constant of a simple RC filter circuit. In most of the world a 50 μs time constant is used. In the Americas and South Korea , 75 μs
20049-460: The receiver to identify a stereo transmission and to regenerate the 38 kHz sub-carrier with the correct phase. The composite stereo multiplex signal contains the Main Channel (L+R), the pilot tone, and the (L−R) difference signal. This composite signal, along with any other sub-carriers, modulates the FM transmitter. The terms composite , multiplex and even MPX are used interchangeably to describe this signal. The instantaneous deviation of
20212-428: The records having been destroyed in 1975. WKCR was allegedly hijacked mid-broadcast once around 1995. The interruption reportedly began with eerie screeches and was followed by silence, then by a woman reciting obituaries, including those of Frank Oppenheimer and several victims of the 1988 bombing of Pan Am Flight 103 . After a couple of minutes, the station took control and came back on air as usual. A recording of
20375-570: The required area is covered without causing interference to other stations further away. Practical transmitter powers range from a few milliwatts to 80 kW. As transmitter powers increase above a few kilowatts, the operating costs become high and only viable for large stations. The efficiency of larger transmitters is now better than 70% (AC power in to RF power out) for FM-only transmission. This compares to 50% before high efficiency switch-mode power supplies and LDMOS amplifiers were used. Efficiency drops dramatically if any digital HD Radio service
20538-570: The required area is covered without causing interference to other stations further away. Practical transmitter powers range from a few milliwatts to 80 kW. As transmitter powers increase above a few kilowatts, the operating costs become high and only viable for large stations. The efficiency of larger transmitters is now better than 70% (AC power in to RF power out) for FM-only transmission. This compares to 50% before high efficiency switch-mode power supplies and LDMOS amplifiers were used. Efficiency drops dramatically if any digital HD Radio service
20701-400: The resulting signal is that it alternates between left and right at 38 kHz, with the phase determined by the 19 kHz pilot signal. Most stereo encoders use this switching technique to generate the 38 kHz subcarrier, but practical encoder designs need to incorporate circuitry to deal with the switching harmonics. Converting the multiplex signal back into left and right audio signals
20864-440: The roof of Philosophy Hall, as well as $ 25,000 worth of master control equipment donated by WMCA . A third of the student volunteers for WKCR-FM were women from the affiliated Barnard College . Until the 1970s, the carrier current WKCR, focused largely on music broadcasting and restricted to campus, coexisted with WKCR‑FM, which covered the entire New York metropolitan area with a greater emphasis on education. Programming
21027-517: The same year as the first AM radio transmission made by Reginald Fessenden . Records indicate that a Columbia University Experimental Wireless Station had set up a cage‑type radio antenna between the chimneys of Havemeyer Hall and Schermerhorn Hall . What is now WKCR‑FM originated as the Wireless Telegraph Club of Columbia University, now under the name Columbia University Amateur Radio Club. Founded in 1908, one year before
21190-401: The scene... Candles are being lit in various windows of Hamilton Hall ... There has been a lot of egg-throwing... The crowd is milling about... Someone is playing " The Marseillaise "... WKCR coverage only stopped for a period of time on April 26, when the university ordered the station to suspend operations. Students demanded the station be allowed to return to the air, and within half an hour
21353-415: The separation as the signal-to-noise ratio worsens, eventually going to mono while still indicating a stereo signal is received. As with monaural transmission, it is normal practice to apply pre-emphasis to the left and right channels before encoding and to apply de-emphasis at the receiver after decoding. In the U.S. around 2010, using single-sideband modulation for the stereo subcarrier was proposed. It
21516-423: The space between Hartley Hall and Hamilton Hall . Within its first year, CURC was broadcasting 18 hours a day, including 10 + 1 ⁄ 2 hours of rebroadcasts from W71NY and W2XMN. After the FCC officially recognized college radio stations in 1946, the station received the official call sign of WKCR (standing for "King's Crown Radio"); the designation was originally used by a Merchant Marine ship,
21679-667: The station broadcast from its backup transmitter atop Carman Hall . Its range was severely reduced, its signal barely reaching past a 20-mile radius until 2003, when the station was able to set up a new antenna at 4 Times Square , where it remains today. WKCR was one of four FM radio stations that transmitted from the World Trade Center at the time of its destruction, the others being WNYC-FM , WKTU , and WPAT-FM . For three weeks beginning on September 17, WKCR loaned its new studio in Lerner Hall to WNYC, which continued broadcasting over its AM adjunct but could not access its headquarters in
21842-419: The station started to heavily emphasize the genre, and has since hosted numerous prominent jazz musicians at its studio. By the 1990s, it had become one of the premier stations for jazz in the United States. As of 2022, about 40% of WKCR's airtime is dedicated to jazz. In June or July 1941, within five months of its official debut, CURC aired the first radio performance by pianist Thelonious Monk . Jerry Newman,
22005-429: The station suspended its regular programming to cover the pro-Palestinian campus occupation . Jazz has been a staple of WKCR's programming since its very founding, in part due to its proximity to Harlem , where bebop was developing during the 1940s. Its first broadcast as an official station with FCC approval began with "Swing is Here", a record with Gene Krupa and Roy Eldridge . After the 1968 protests at Columbia,
22168-673: The station was soon used to communicate with stations from other universities and other stations in New York City. It engaged in its first test with the Wireless Association at Princeton University in 1909, and in March of that year, it was used to receive the results of a basketball game against the University of Pennsylvania from The Bellevue-Stratford Hotel in Philadelphia , the first such use of radio by college students. By 1915,
22331-527: The station; notable albums that were recorded or edited at WKCR include Live in New York , featuring Mississippi Fred McDowell and Blues from the Apple , featuring Charles Walker and the New York City Blues Band. WKCR began making plans in 1975 to move its transmitter to 1 World Trade Center , citing deteriorating signal quality due to the construction of the nearby Citigroup Center . Fundraising
22494-462: The switching harmonics. Converting the multiplex signal back into left and right audio signals is performed by a decoder, built into stereo receivers. Again, the decoder can use a switching technique to recover the left and right channels. In addition, for a given RF level at the receiver, the signal-to-noise ratio and multipath distortion for the stereo signal will be worse than for the mono receiver. For this reason many stereo FM receivers include
22657-436: The top 25 U.S. radio markets to transmit in Quadraplex. The test results hopefully would prove to the FCC that the system was compatible with existing two-channel stereo transmission and reception and that it did not interfere with adjacent stations. There were several variations on this system submitted by GE, Zenith, RCA, and Denon for testing and consideration during the National Quadraphonic Radio Committee field trials for
22820-418: The transmitted signal. Because transmitted FM signals use significantly more bandwidth than AM signals, this form of modulation is commonly used with the higher ( VHF or UHF ) frequencies used by TV , the FM broadcast band , and land mobile radio systems . The maximum frequency deviation of the carrier is usually specified and regulated by the licensing authorities in each country. For a stereo broadcast,
22983-423: The transmitter carrier frequency due to the stereo audio and pilot tone (at 10% modulation) is where A and B are the pre-emphasized left and right audio signals and f p {\displaystyle f_{p}} =19 kHz is the frequency of the pilot tone. Slight variations in the peak deviation may occur in the presence of other subcarriers or because of local regulations. Another way to look at
23146-422: The turmoil at the station after the 9/11 attacks. WKCR was one of several college radio stations which had been fined by the FCC in recent years, a practice that was criticized as punitive for its lack of distinction between commercial stations and those run by students, which are generally characterized by high turnover and lower budgets. The FCC's policy towards college stations was relaxed in 2013. In April 2024,
23309-426: The university tunnel system , were able to appropriate campus phone lines so that reporters could instantly communicate with station headquarters from any of the occupied buildings. According to one story, when the police stormed Low Memorial Library , a staff member picked up one of the phones and began reporting on the events. When a policeman came over and destroyed the phone he was using, the student simply picked up
23472-426: The use of two FM stations; one transmitting the front audio channels, the other the rear channels. A breakthrough came in 1970 when KIOI ( K-101 ) in San Francisco successfully transmitted true quadraphonic sound from a single FM station using the Quadraplex system under Special Temporary Authority from the FCC . Following this experiment, a long-term test period was proposed that would permit one FM station in each of
23635-515: The world to Biggie Smalls , Eminem , Jay-Z , Big L , Big Pun , Fat Joe , Wu Tang Clan , Mobb Deep , and the Fugees , among others. The Stretch Armstrong and Bobbito Show was voted the "best hip-hop show of all time" by The Source in 1998. WKCR's transmitter was destroyed on September 11, 2001, when a hijacked plane destroyed the North Tower of the World Trade Center . For the next two years,
23798-466: The world, the FM broadcast band falls within the VHF part of the radio spectrum . Usually 87.5 to 108.0 MHz is used, or some portion of it, with few exceptions: The frequency of an FM broadcast station (more strictly its assigned nominal center frequency) is usually a multiple of 100 kHz. In most of South Korea , the Americas , the Philippines , and the Caribbean , only odd multiples are used. Some other countries follow this plan because of
23961-651: Was 27.5 kHz. The IF bandwidth was ±5 kHz, as the only goal at the time was to relay AM radio-quality audio. This transmission system used 75 μs audio pre-emphasis like the main monaural audio and subsequently the multiplexed stereo audio. In the late 1950s, several systems to add stereo to FM radio were considered by the FCC . Included were systems from 14 proponents including Crosby, Halstead, Electrical and Musical Industries, Ltd ( EMI ), Zenith, and General Electric. The individual systems were evaluated for their strengths and weaknesses during field tests in Uniontown, Pennsylvania , using KDKA-FM in Pittsburgh as
24124-415: Was accused of failing to replace broken equipment, which had caused the station's frequency to creep up from 89.9 to 89.95 MHz. WKCR Manager Andy Caploe responded that the station could not have known whether there were any problems with the transmitter in the first place, because its testing equipment was also broken. The station finally made the move in April 1985, where it would continue broadcast from for
24287-616: Was atop the highest mountain in the northeast United States, Mount Washington , New Hampshire (shut down in 1948); and W9XAO/W55M/WTMJ-FM Milwaukee, Wisconsin (went off air in 1950). A commercial FM broadcasting band was formally established in the United States as of January 1, 1941, with the first fifteen construction permits announced on October 31, 1940. These stations primarily simulcast their AM sister stations, in addition to broadcasting lush orchestral music for stores and offices, classical music to an upmarket listenership in urban areas, and educational programming. On June 27, 1945
24450-616: Was atop the highest mountain in the northeast United States, Mount Washington , New Hampshire (shut down in 1948); and W9XAO/W55M/WTMJ-FM Milwaukee, Wisconsin (went off air in 1950). A commercial FM broadcasting band was formally established in the United States as of January 1, 1941, with the first fifteen construction permits announced on October 31, 1940. These stations primarily simulcast their AM sister stations, in addition to broadcasting lush orchestral music for stores and offices, classical music to an upmarket listenership in urban areas, and educational programming. On June 27, 1945
24613-518: Was based on the Telefunken High ;Com broadband compander system, but was never introduced commercially in FM broadcasting. Yet another system was the CX -based noise reduction system FMX implemented in some radio broadcasting stations in the United States in the 1980s. FM broadcasting has included subsidiary communications authorization (SCA) services capability since its inception, as it
24776-404: Was broadcast from the university sundial . Spearheading WKCR's post-1968 transition into a jazz-oriented radio station was Phil Schaap , one of the foremost jazz experts of the late 20th century. He became a disc jockey at the station as a freshman in 1970, and continued to work there pro bono after his graduation until his death in 2021. He was most well known on the station for Bird Flight ,
24939-549: Was completed in September, and the station was given until March 31, 1976, to build its new transmitter. Due to a bureaucratic stalemate, the deadline was missed, and the station had to apply for a new lease. The Columbia Daily Spectator reported on September 14, 1976, that negotiations with the Port Authority of New York and New Jersey were in their final stages, and that the move was projected to take place before January 1, 1977. In July 1977, The New York Times announced that WKCR would move by September 15 of that year, and would
25102-506: Was dealing with a hum which had interfered with broadcasts for the past three weeks. The station began transmitting from the Twin Towers for the first time at 9:30 a.m. on July 20, though the broadcast was shut down after 45 minutes by the FCC, forcing WKCR to repair and continue to use its old antenna. In July 1982, the FCC fined the station $ 8,000 for violations of federal equipment and licensing regulation, which were discovered during an allegedly routine and random inspection. The station
25265-507: Was founded in 1940. The original station was built almost single‑handedly by electrical engineering student William Hutchins in his room in John Jay Hall . Armstrong donated a microphone and turntables to the fledgling station. While setting the station up, the Radio Club engaged in illegal experimentation, exceeding FCC minimum power regulations for carrier current transmission . Under
25428-495: Was largely university sports, lecture series, classical music, and broadcasts from the United Nations, including many interviews with representatives of foreign nations. WKCR‑FM began broadcasting from the DuMont Building on Madison Avenue in 1958, and in 1964 it became the first noncommercial radio station to broadcast in stereo. During the 1960s, the station would continue to develop its educational content. Members of
25591-469: Was preceded by student involvement in W2XMN , an experimental FM station founded by Armstrong, for which the CURC provided programming. Originally an education-focused station, since the Columbia University protests of 1968 , WKCR-FM has shifted its focus towards alternative musical programming, with an emphasis on jazz , classical, and hip-hop . WKCR has been described as one of the premier stations for jazz in
25754-457: Was rejected due to lack of high frequency stereo separation and reduction in the main channel signal-to-noise ratio. The GE and Zenith systems, so similar that they were considered theoretically identical, were formally approved by the FCC in April 1961 as the standard stereo FM broadcasting method in the United States and later adopted by most other countries. It is important that stereo broadcasts be compatible with mono receivers. For this reason,
25917-565: Was seen as another service which licensees could use to create additional income. Use of SCAs was particularly popular in the US, but much less so elsewhere. Uses for such subcarriers include radio reading services for the blind , which became common and remain so, private data transmission services (for example sending stock market information to stockbrokers or stolen credit card number denial lists to stores, ) subscription commercial-free background music services for shops, paging ("beeper") services, alternative-language programming, and providing
26080-565: Was seen as another service which licensees could use to create additional income. Use of SCAs was particularly popular in the US, but much less so elsewhere. Uses for such subcarriers include radio reading services for the blind , which became common and remain so, private data transmission services (for example sending stock market information to stockbrokers or stolen credit card number denial lists to stores, ) subscription commercial-free background music services for shops, paging ("beeper") services, alternative-language programming, and providing
26243-482: Was tested in Germany between July 1979 and December 1981 by IRT . It was based on the Telefunken High Com broadband compander system, but was never introduced commercially in FM broadcasting. Yet another system was the CX -based noise reduction system FMX implemented in some radio broadcasting stations in the United States in the 1980s. FM broadcasting has included subsidiary communications authorization (SCA) services capability since its inception, as it
26406-424: Was theorized to be more spectrum-efficient and to produce a 4 dB s/n improvement at the receiver, and it was claimed that multipath distortion would be reduced as well. A handful of radio stations around the country broadcast stereo in this way, under FCC experimental authority. It may not be compatible with very old receivers, but it is claimed that no difference can be heard with most newer receivers. At present,
26569-446: Was used in the earliest days of FM broadcasting. According to a BBC report from 1946, 100 μs was originally considered in the US, but 75 μs subsequently adopted. Long before FM stereo transmission was considered, FM multiplexing of other types of audio-level information was experimented with. Edwin Armstrong, who invented FM, was the first to experiment with multiplexing, at his experimental 41 MHz station W2XDG located on
#529470