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86-582: WGBH (89.7 FM , "GBH 89.7") is a public radio station located in Boston, Massachusetts . WGBH is a member station of National Public Radio (NPR) and affiliate of Public Radio Exchange (PRX) and American Public Media (APM). The license-holder is WGBH Educational Foundation , which also owns company flagship WGBH-TV and WGBX-TV , along with WGBY-TV in Springfield . The station, dubbed Boston Public Radio in 2009, renamed Boston's Local NPR , broadcasts

172-614: A news-and-information format during the daytime (including NPR News programs and PRX's The World , which is a co-production of WGBH and PRX, and formerly the BBC World Service ), and jazz music during the nighttime. Prior to December 1, 2009, the station had a mixed news and entertainment format, featuring local jazz and blues programs, with the station tagline being ‘’Boston’s NPR Arts & Culture Station’’, to differentiate it from all news WBUR-FM , also located in Boston and known at

258-412: A codicil to his will written "amidst the ruins of Thebes" and, subsequently, in letters written from Egypt, he further amplified his ideas about the trust. Although he expressed a preference for lectures on religion and on topics that would contribute to the material prosperity of the region, he ceded to his trustee discretion to "establish lectures on any subject that, in his opinion, the wants and taste of

344-510: 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

430-557: 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

516-811: A strong city-grade signal to Rhode Island's capital. WGBH also operates a separately-programmed service for the Cape Cod and Islands area, with a full-time news-and-information format. This service is simulcast on three stations: WCAI in Woods Hole , WNAN in Nantucket , and WZAI in Brewster . WGBH also owns WCRB , a classical music station. This service is simulcast by WJMF in Smithfield, Rhode Island (near Providence). Both WCAI and WCRB are also simulcast on HD Radio subcarriers of WGBH itself. The WCRB simulcast on WGBH-HD2

602-470: 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

688-441: A trust to fund free public lectures in Boston on the subjects of philosophy, natural history, and the arts and sciences. The trust—or Lowell Institute, as it came to be known—had an unusual mode of governance: a single trustee who was empowered to appoint his successor and who was, in the language of Lowell's will, "always choose in preference to all others some male descendant of my grandfather, John Lowell, provided there be one who

774-604: A two-hour segment named Boston Public Radio . The station also started carrying the APM show Marketplace . In February 2013, Jim Braude and Margery Eagan (previously co-hosts of the Jim & Margery Show talk show on WTKK ) were brought on to co-host Boston Public Radio . They brought along with them the monthly Ask the Governor program, a series that WGBH also provides to other local stations free of charge. WGBH and WBUR-FM both serve

860-500: A variety of classical music programming, mostly during the day on weekdays, weekend mornings, and Sunday afternoons. These broadcasts included (in addition to generally available recordings) recordings made by WGBH of regional chamber music and solo recital performances, live in-studio performances and interviews, as well as live broadcasts of the Boston Symphony Orchestra from Symphony Hall (on Friday afternoons when

946-469: A week, replacing weeknight evening and overnight jazz programming with public radio news and information programming. The cutback in jazz took place on July 2, 2012. Eric Jackson still does nine hours of jazz programming on weekends; Steve Schwartz's Friday show was eliminated completely. The same notice announced that in July 2012, WGBH would combine the hour-long Emily Rooney Show and Callie Crossley Show into

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1032-539: A will in which, according to his biographer, "he set aside a large portion of his ample property to be expended, forever, in the support of those courses of lectures in the city of Boston." Over the course of the next four years, Lowell traveled through France, the Netherlands , Belgium , Italy, Greece , Turkey , Armenia , Persia , and Egypt , down the Nile to Khartoum , through Ethiopia , and ultimately to India. Although

1118-525: 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

1204-422: 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

1290-535: Is also relayed by translator W242AA (96.3 FM) East Cambridge , as the Federal Communications Commission regards it as a WGBH translator (from October 1991 until April 8, 2010, W242AA carried WGBH's main service). WGBH, WCAI, and WCRB all stream their programming worldwide on the Internet. WGBH Educational Foundation received its first broadcasting license (for radio) in 1951 under the auspices of

1376-408: 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

1462-422: 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

1548-871: Is competent to hold the office of trustee, and of the name of Lowell." The first lecture supported by the trust, by Yale geologist Benjamin Silliman , was offered in December 1839. Under its first trustee, the founder's first cousin, John Amory Lowell (1798–1881), the Institute flourished. The list of Lowell Lecturers during his tenure was a veritable pantheon of the most internationally celebrated figures in science, literature, political economy , philosophy, and theology, including Britain's most celebrated geologist, Sir Charles Lyell , Swiss naturalist Louis Agassiz , and novelists Charles Dickens and William Makepeace Thackeray . The lectures were so immensely popular that crowds crushed

1634-581: 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 ,

1720-434: Is featured, such as This American Life , The Moth , Selected Shorts , Freakonomics , On Being , Radiolab , Studio 360 , and The New Yorker Radio Hour . Jazz music is broadcast on weekend evenings and overnights. Until July 2, 2012, WGBH also carried jazz during the evening and overnight hours on Mondays through Thursdays; this programming was cut back to increase news and information programming during

1806-477: Is locally produced by WGBH. WBUR carries Talk of the Nation , On Point , Here and Now , and Car Talk , which are not heard on WGBH. The latter three programs are produced locally by WBUR. The two stations also broadcast somewhat different selections from among the programs available through their national network affiliations. FM broadcasting Throughout the world, the FM broadcast band falls within

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1892-522: Is located within the Blue Hills Reservation, and is the highest natural point in the Boston area. Mai Cramer, longtime host of the program Blues After Hours , jokingly maintained that the station's call sign stands for: "We Got Blues Here!" According to Nielsen data aggregated by Ken Mills, a Minneapolis broadcast consultant, as of June 2017 the number of WGBH's listeners has nearly doubled since 2012, increasing from 235,200 to 445,200. WGBH

1978-480: 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

2064-671: 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

2150-487: 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

2236-506: 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. John Lowell Jr. (philanthropist) John Lowell Jr. (May 11, 1799 – March 4, 1836) was an American businessman, early philanthropist, and through his will, founder of the Lowell Institute . Lowell was the son of pioneer industrialist Francis Cabot Lowell (1775–1817), one of

2322-504: 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

2408-554: 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

2494-626: 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

2580-527: Is the 10th-most-popular NPR news station in the United States. The main WGBH signal operates at 98,000 watts , which is strong enough to cover the eastern half of Massachusetts , as well as Rhode Island , Eastern Connecticut , much of southern New Hampshire , and the southern tip of Maine . Indeed, for years WGBH claimed Providence, Rhode Island , as part of its primary coverage area; the station still provides

2666-427: 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

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2752-489: The Five Colleges to set up a repeater for western Massachusetts, WFCR . That repeater became a full-fledged station in 1962, and is now the flagship NPR outlet for western Massachusetts. WGBH was a charter member of NPR, and was one of the stations that carried the inaugural broadcast of All Things Considered in 1971. In the summer of 2016, the station began broadcasting some of its programming from an on-air studio in

2838-580: 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

2924-513: The Lowell Institute Cooperative Broadcasting Council, a consortium of local universities and cultural institutions, whose collaboration stems from an 1836 bequest by textile manufacturer John Lowell Jr. calling for free public lectures for the citizens of Boston. WGBH signed on October 6, 1951 , with a live broadcast of the Boston Symphony Orchestra . Within a decade, it had grown enough that it partnered with

3010-516: The Unitarian elite and the evangelical urban masses intensified in the 1820s, as followers of popular ministers like Lyman Beecher openly challenged elite-controlled institutions like Harvard and the Boston Athenaeum using a variety of voluntary associations—young men's and mechanics societies, lyceums, debating clubs, and temperance groups. The continuing erosion of the elite's cultural authority

3096-620: 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

3182-492: 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

3268-659: The Boston Common Council and in the Massachusetts State Senate . The 1820s and 1830s were a turbulent period in New England , marked by intense political and religious conflict between an insurgent popular democracy, which challenged economic and religious establishments, and an emergent capitalist elite which, though almost invariably defeated at the polls, was learning to use its wealth to advance its political agenda through non-political means. Conflict between

3354-489: The Boston area, and there is some overlap between programming on the two stations (i.e. All Things Considered , Morning Edition ). When WGBH announced plans to convert their daytime hours to news and information, there was speculation as to how much overlap between the two stations there would be. WGBH broadcasts The World and the sound portion of the PBS NewsHour , while WBUR does not. As mentioned above, The World

3440-590: The Boston public schools, young Lowell was taken by his father to Europe and placed at the high school of Edinburgh . In 1813, at the age of 14, he returned to America and entered Harvard College . Plagued with ill health, he left college after two years and entered his family's mercantile firm, sailing before the mast to India , the East Indies , and England. Returning from his voyages with invigorated health, Lowell devoted himself to business and, in his leisure time, to book collecting, reading, and politics, serving on

3526-638: 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

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3612-699: 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

3698-511: 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

3784-451: 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

3870-458: 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

3956-969: 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

4042-460: 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,

4128-674: 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

4214-576: The age may demand". Lowell became gravely ill during a camel trip across the Egyptian desert and died on March 4, 1836, shortly after arriving in Bombay , India. Although large-scale philanthropic gestures were a relative novelty in early nineteenth century America, the idea of an elite institution providing popular lectures by eminent scientists and scholars was not. Having spent much of his youth in England, Lowell

4300-454: 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

4386-511: 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

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4472-406: The bequest providing for "the maintenance and support of public lectures, to be delivered in Boston, upon philosophy, natural history , the arts and sciences, or any of them, as the trustee shall, from time to time, deem expedient for the promotion of the moral, and intellectual, and physical instruction or education of the citizens of Boston" had been set forth before his departure from Boston, "– in

4558-402: 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

4644-431: 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

4730-535: The evening and overnight hours. Saturday programming consists of various syndicated programs such as Weekend Edition , Wait Wait... Don't Tell Me! , This American Life , and others. Celtic music was featured in the long-running locally produced WGBH show, A Celtic Sojourn, hosted by Brian O'Donovan from 1986 until his death in 2023. Programs originating from WGBH for the local market include: Programs originating from WGBH that are also broadcast in other markets include: Until December 1, 2009, WGBH broadcast

4816-553: 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

4902-530: The founders of the Boston region's textile industry , and Hannah Jackson, sister of Patrick Tracy Jackson , another industrial pioneer. His grandfather and namesake, Judge John Lowell (1743–1802), referred to as The Old Judge , served in the Congress of the Confederation in 1782 and was appointed later to federal benches by presidents George Washington and John Adams . After receiving his early education in

4988-505: 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

5074-467: 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

5160-496: 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

5246-517: 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

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5332-516: 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

5418-564: 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

5504-405: 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

5590-497: The newly renovated Boston Public Library Johnson building, fronting on Boylston Street in Back Bay . In May 2024, WGBH laid off 31 employees across 13 departments, a 4% staff reduction. Production of three television programs was also suspended. WGBH broadcasts news programming, generally from NPR or PRI . On weekends and some weekday evenings, a variety of public affairs programming and other informational/entertainment programming

5676-487: 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

5762-602: The orchestra is scheduled to play), and Tanglewood (on Sunday afternoons in the summer). In addition, WGBH's music programming also included folk music on Saturday afternoons and blues on Saturday evenings. In September 2009, the WGBH Educational Foundation announced a deal to acquire WCRB , a local classical music station. It consolidated all classical music programming on WCRB, and changed WGBH to an all-news and information format. A significant number of WGBH's traditional classical listeners were sacrificed in

5848-433: 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

5934-551: 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:

6020-400: 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

6106-515: 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

6192-570: 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

6278-400: 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

6364-415: 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

6450-451: The time as "Boston's NPR News Station". Following the rebranding, much of the station's culture-related programming was dropped in favor of nationally syndicated NPR, PRI, and APM programs. "GBH" stands for Great Blue Hill , the site of WGBH's FM transmitter in Milton, Massachusetts , as well as the original location of WGBH-TV's transmitter. Great Blue Hill has an elevation of 635 feet (193 m),

6536-516: 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

6622-506: The transition, as WCRB transmits from the North Shore of Boston, and cannot be received reliably in areas to the south, including Cape Cod. In November 2009 the station announced that its long-running Saturday afternoon folk and Saturday evening blues programs would be discontinued in December, however A Celtic Sojourn and A Prairie Home Companion would remain. On June 20, 2012, it was announced that WGBH would cut back jazz to nine hours

6708-423: 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

6794-527: 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

6880-755: 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

6966-616: 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

7052-516: Was deeply troubling to Lowell and his contemporaries. Within a few short months in 1830 and 1831, tragedy struck Lowell's household, with the deaths of his wife and two children. Heartbroken, John Lowell retired from business and attempted to assuage his grief with travel, first to the western states and subsequently in Europe, the Middle East, Africa, and Asia. Before departing for Europe in 1832, he wrote

7138-565: 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

7224-639: 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

7310-424: 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,

7396-663: Was undoubtedly familiar with the Royal Institution – an entity that sponsored basic scientific research and popular lectures and demonstrations. Lowell, a supporter of the Lyceum movement , first showed interest in providing education for the public as a founding member of the Boston Society for the Diffusion of Useful Knowledge in 1830. After becoming ill while traveling through Egypt in 1835, John Lowell Jr. revised his will to create

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