AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmissions, but also on the longwave and shortwave radio bands.
126-661: WBAA (920 AM ) and WBAA-FM (101.3 FM ) are jointly operated non-commercial educational radio stations licensed to West Lafayette, Indiana , United States, both serving the Lafayette metro area and the Indianapolis area with public radio formats. The stations were founded by Purdue University , but in 2022, 100 years after WBAA's start, ownership was transferred to Metropolitan Indianapolis Public Media , Inc. (MIPM), which also owns WFYI radio and television in Indianapolis. Both stations originate from studios in
252-472: A "chain". The Radio Corporation of America (RCA), General Electric , and Westinghouse organized a competing network around its own flagship station, RCA's WJZ (now WABC) in New York City, but were hampered by AT&T's refusal to lease connecting lines or allow them to sell airtime. In 1926 AT&T sold its radio operations to RCA, which used them to form the nucleus of the new NBC network. By
378-846: A 10 shilling receiver license fee. Both highbrow and mass-appeal programmes were carried by the National and Regional networks. The period from the early 1920s through the 1940s is often called the "Golden Age of Radio". During this period AM radio was the main source of home entertainment, until it was replaced by television. For the first time entertainment was provided from outside the home, replacing traditional forms of entertainment such as oral storytelling and music from family members. New forms were created, including radio plays , mystery serials, soap operas , quiz shows , variety hours , situation comedies and children's shows . Radio news, including remote reporting, allowed listeners to be vicariously present at notable events. Radio greatly eased
504-437: A CBS Radio affiliate, WSBT-TV was primarily affiliated with CBS Television. A second WSBT-FM, this time on 101.5 MHz, was later authorized, and, twelve years after the original WSBT-FM shut down, started broadcasting on August 12, 1962. At first it simulcast WSBT. In the late 1960s, WSBT-FM began separate programming, airing beautiful music . In 1984, the station switched to locally programmed adult contemporary music, with
630-401: A career as a radio and television sportscaster. Lew Wood later was the news anchor on Today in 1975 and 1976, and actors George Peppard and Karen Black also worked at WBAA while at Purdue. WBAA was one of the charter members of NPR and carried its inaugural broadcast, the first edition of All Things Considered , on May 1, 1971. The addition of NPR to WBAA helped increase interest in
756-570: A central station to all parts of the United States", he was unable to overcome the inherent distance limitations of this technology. The earliest public radiotelegraph broadcasts were provided as government services, beginning with daily time signals inaugurated on January 1, 1905, by a number of U.S. Navy stations. In Europe, signals transmitted from a station located on the Eiffel Tower were received throughout much of Europe. In both
882-467: A commercial station in Indianapolis . WKBF got a power boost to 500 watts, but now had to share air time with the other two stations, with WKBF allotted four-sevenths, two-sevenths assigned to WCMA, and the remaining seventh assigned to WBAA, primarily on Mondays and Fridays. On the afternoon of March 14, 1929, a fire erupted that destroyed the facilities of WBAA; it was reported to have started when
1008-610: A concerted attempt to specify performance of AM receivers through the 1993 AMAX standard, a joint effort of the EIA and the NAB, with FCC backing... The FCC rapidly followed up on this with codification of the CQUAM AM stereo standard, also in 1993. At this point, the stage appeared to be set for rejuvenation of the AM band. Nevertheless, with the legacy of confusion and disappointment in the rollout of
1134-635: A consortium, the British Broadcasting Company (BBC), established on 18 October 1922, which was given a monopoly on broadcasting. This enterprise was supported by a tax on radio sets sales, plus an annual license fee on receivers, collected by the Post Office. Initially the eight stations were allowed regional autonomy. In 1927, the original broadcasting organization was replaced by a government chartered British Broadcasting Corporation . an independent nonprofit supported solely by
1260-564: A continuous-wave (CW) transmitter. Fessenden began his research on audio transmissions while doing developmental work for the United States Weather Service on Cobb Island, Maryland. Because he did not yet have a continuous-wave transmitter, initially he worked with an experimental "high-frequency spark" transmitter, taking advantage of the fact that the higher the spark rate, the closer a spark-gap transmission comes to producing continuous waves. He later reported that, in
1386-580: A few " telephone newspaper " systems, most of which were established in Europe, beginning with the Paris Théâtrophone . With this in mind, most early radiotelephone development envisioned that the device would be more profitably developed as a "wireless telephone" for personal communication, or for providing links where regular telephone lines could not be run, rather than for the uncertain finances of broadcasting. The person generally credited as
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#17327808002431512-463: A few hundred ( Hz ), to increase its rotational speed and so generate currents of tens-of-thousands Hz, thus producing a steady continuous-wave transmission when connected to an aerial. The next step, adopted from standard wire-telephone practice, was to insert a simple carbon microphone into the transmission line, to modulate the carrier wave signal to produce AM audio transmissions. However, it would take many years of expensive development before even
1638-516: A home audio device prior to the introduction of the high-fidelity , long-playing record in the late 1940s. Listening habits changed in the 1960s due to the introduction of the revolutionary transistor radio (Regency TR-1, the first transistor radio released December 1954), which was made possible by the invention of the transistor in 1948. (The transistor was invented at Bell labs and released in June 1948.) Their compact size — small enough to fit in
1764-474: A listening site at Plymouth, Massachusetts. An American Telephone Journal account of the December 21 alternator-transmitter demonstration included the statement that "It is admirably adapted to the transmission of news, music, etc. as, owing to the fact that no wires are needed, simultaneous transmission to many subscribers can be effected as easily as to a few", echoing the words of a handout distributed to
1890-487: A majority of early broadcasting stations operated on mediumwave frequencies, whose limited range generally restricted them to local audiences. One method for overcoming this limitation, as well as a method for sharing program costs, was to create radio networks , linking stations together with telephone lines to provide a nationwide audience. In the U.S., the American Telephone and Telegraph Company (AT&T)
2016-506: A national scale. The introduction of nationwide talk shows, most prominently Rush Limbaugh 's beginning in 1988, was sometimes credited with "saving" AM radio. However, these stations tended to attract older listeners who were of lesser interest to advertisers, and AM radio's audience share continued to erode. In 1961, the FCC adopted a single standard for FM stereo transmissions, which was widely credited with enhancing FM's popularity. Developing
2142-712: A news service among Western Conference schools. For audio transmissions, the station added a small transmitter that had been constructed as a thesis assignment by R. H. Vehling, class of 1921. Effective December 1, 1921, the United States Department of Commerce , which regulated radio at this time, adopted regulations requiring that stations broadcasting to the general public had to have a Limited Commercial license. Two wavelengths were designated for use by broadcasting stations: 360 meters (833 kHz) for "entertainment" programs and 485 meters (619 kHz) for "market and weather" reports. In order to conform with
2268-564: A news- and talk-focused AM station. A fundraising drive was led by Purdue's class of 1942 to finance construction. WBAA-FM went into operation on February 1, 1993, providing a mostly automated classical music service. The Hall of Music studios were also remodeled to support the second station. In September 1992, WBAA announced it would cease to broadcast programs distributed by NPR because of a 20 percent increase in subscription fees to NPR for 1993. It replaced NPR fare with shows from other public radio distributors, such as American Public Radio and
2394-665: A partly commercial operation; this was vetoed by the Purdue board of trustees. The Federal Communications Commission (FCC) approved in November 1940, setting up an eventful 1941 for the Purdue station. In February, the studios moved out of three rooms in the Electrical Engineering Building to the Elliott Hall of Music . The new transmitter site was not ready for several more months, but one last change
2520-399: A policy allowing AM stations to simulcast over FM translator stations. Translators had previously been available only to FM broadcasters, in order to increase coverage in fringe areas. Their assignment for use by AM stations was intended to approximate the station's daytime coverage, which in cases where the stations reduced power at night, often resulted in expanded nighttime coverage. Although
2646-486: A prototype alternator-transmitter would be ready, and a few years beyond that for high-power versions to become available. Fessenden worked with General Electric 's (GE) Ernst F. W. Alexanderson , who in August 1906 delivered an improved model which operated at a transmitting frequency of approximately 50 kHz, although at low power. The alternator-transmitter achieved the goal of transmitting quality audio signals, but
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#17327808002432772-423: A result, AM radio tends to do best in areas where FM frequencies are in short supply, or in thinly populated or mountainous areas where FM coverage is poor. Great care must be taken to avoid mutual interference between stations operating on the same frequency. In general, an AM transmission needs to be about 20 times stronger than an interfering signal to avoid a reduction in quality, in contrast to FM signals, where
2898-500: A sequential roster of available call signs, and the station was one of 19 new stations that month that were issued call signs starting with "WGA". Because South Bend was the home of the Studebaker automobile company, it was suggested that "World's Greatest Automotive Zone" was an appropriate slogan based on these call letters. WGAZ was South Bend's second commercial radio station, after WBAQ, licensed to Myron L. Harmon and located at
3024-461: A service noted for its limited agricultural extension and educational programming as well as Purdue sports broadcasts, it gradually improved its facilities and expanded its output over its first 20 years on air. The station was one of NPR's charter members in 1971. WBAA-FM, branded as "WBAA Classical", features a mixture of NPR news and classical music . WBAA-FM began broadcasting in 1993. The station also transmits an HD2 digital subchannel, which
3150-452: A shirt pocket — and lower power requirements, compared to vacuum tubes, meant that for the first time radio receivers were readily portable. The transistor radio became the most widely used communication device in history, with billions manufactured by the 1970s. Radio became a ubiquitous "companion medium" which people could take with them anywhere they went. The demarcation between what is considered "experimental" and "organized" broadcasting
3276-401: A short time daily". On December 22, 1952, WSBT-TV first signed on, originally on channel 34, and later moving to channel 22. WSBT-TV was one of the first stations to broadcast on the newly created UHF band, thus most existing TV sets, which were designed only for reception on the original VHF band, needed a converter installed before they could pick up its signals. Because the AM station was
3402-427: A short-range "wireless telephone" demonstration, that included simultaneously broadcasting speech and music to seven locations throughout Murray, Kentucky. However, this was transmitted using induction rather than radio signals, and although Stubblefield predicted that his system would be perfected so that "it will be possible to communicate with hundreds of homes at the same time", and "a single message can be sent from
3528-472: A spark ignited hydrogen gas that was leaking from batteries. The blaze also caused smoke damage to the Electrical Engineering Building in which WBAA was located; some students had to be rescued from windowsills, where they had fled the advancing fire. Purdue immediately began planning to rebuild WBAA as a 1,000-watt station, but the FRC would only allow it to continue as a 500-watt outlet. Operations of WBAA resumed at
3654-461: A widespread audience — dates back to the founding period of radio development, even though the earliest radio transmissions, originally known as "Hertzian radiation" and "wireless telegraphy", used spark-gap transmitters that could only transmit the dots-and-dashes of Morse code . In October 1898 a London publication, The Electrician , noted that "there are rare cases where, as Dr. [Oliver] Lodge once expressed it, it might be advantageous to 'shout'
3780-784: Is branded as "WBAA Jazz". WBAA on AM carries a service of news and talk programs, with such key shows as Morning Edition , All Things Considered , and Marketplace , as well as the BBC World Service in overnight hours. Each Thursday, the local program Ask the Mayor features the leader of a community in west central Indiana. WBAA-FM offers a service of classical music with two locally hosted blocks; Classical Music Indy from Indianapolis in overnights; and Performance Today and other music shows. Morning Edition , All Things Considered , and Marketplace are also simulcast on FM. WBAA-FM's HD2 subchannel airs jazz music from
3906-406: Is comparable to or better in audio quality than a standard analog broadcast". Despite the various actions, AM band audiences continued to contract, and the number of stations began to slowly decline. A 2009 FCC review reported that "The story of AM radio over the last 50 years has been a transition from being the dominant form of audio entertainment for all age groups to being almost non-existent to
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4032-502: Is largely arbitrary. Listed below are some of the early AM radio broadcasts, which, due to their irregular schedules and limited purposes, can be classified as "experimental": People who weren't around in the Twenties when radio exploded can't know what it meant, this milestone for mankind. Suddenly, with radio, there was instant human communication. No longer were our homes isolated and lonely and silent. The world came into our homes for
4158-492: Is located in the southern portion of South Bend, off Ironwood Road. With a good radio, WSBT's signal can be picked up from Lake Michigan to Fort Wayne . WSBT is not licensed to broadcast a digital HD signal. WSBT is the flagship station for University of Notre Dame football and men's basketball , as well as the South Bend Cubs . On December 1, 1921, the U.S. Department of Commerce, in charge of radio at
4284-645: Is simpler than later transmission systems. An AM receiver detects amplitude variations in the radio waves at a particular frequency, then amplifies changes in the signal voltage to operate a loudspeaker or earphone . However, the simplicity of AM transmission also makes it vulnerable to "static" ( radio noise , radio frequency interference ) created by both natural atmospheric electrical activity such as lightning, and electrical and electronic equipment, including fluorescent lights, motors and vehicle ignition systems. In large urban centers, AM radio signals can be severely disrupted by metal structures and tall buildings. As
4410-711: The BBC World Service . The decision generated significant pushback from listeners; WILL in Illinois began to woo disaffected WBAA listeners seeking their favorite NPR shows, going as far as to run newspaper ads in Lafayette. In 1995, local listeners began to receive some NPR programming again when WVXU in Cincinnati acquired WNDY, a silent commercial station licensed to Crawfordsville , and relaunched it as WVXI ; however, WVXI only aired Morning Edition and not All Things Considered . Purdue officials began approaching
4536-602: The Christian contemporary programming of 104.7 WFRN-FM in Elkhart . It served mainly to fill in the gaps in WSBT's nighttime signal. WSBT changes to a different directional pattern after sunset, resulting in marginal nighttime coverage outside St. Joseph County . On June 28, 2021, W241AD dropped its simulcast with WSBT (leaving WSBT as AM only) and launched a country music format, branded as "96.1 The Ton", with WQLQ -HD3 as
4662-615: The Edward C. Elliott Hall of Music on the Purdue campus, with transmitter sites south of Lafayette at the Throckmorton Purdue Agricultural Center. WBAA, branded as "WBAA News", broadcasts a news-oriented format, with programming from National Public Radio (NPR). WBAA is the oldest operating radio station in Indiana, beginning in 1922 and with several antecedents on the Purdue campus. Originally
4788-578: The Electronic Industries Association (EIA) and the National Association of Broadcasters (NAB) with the intention of helping AM stations, especially ones with musical formats, become more competitive with FM broadcasters by promoting better quality receivers. However, the stereo AM and AMAX initiatives had little impact, and a 2015 review of these events concluded that Initially the consumer manufacturers made
4914-625: The Emergency Alert System (EAS). Some automakers have been eliminating AM radio from their electric vehicles (EVs) due to interference from the electric motors , but the lawmakers argue that this is a safety risk and that car owners should have access to AM radio regardless of the type of vehicle they drive. The proposed legislation would require all new vehicles to include AM radio at no additional charge, and it would also require automakers that have already eliminated AM radio to inform customers of alternatives. AM radio technology
5040-493: The Federal Emergency Management Agency (FEMA) expressed concerns that this would reduce the effectiveness of emergency communications. In May 2023, a bipartisan group of lawmakers in the United States introduced legislation making it illegal for automakers to eliminate AM radio from their cars. The lawmakers argue that AM radio is an important tool for public safety due to being a component of
5166-652: The Stratovision program of the Midwest Program on Airborne Television Instruction , which used flying TV transmitters to broadcast educational TV content over a wide area. Purdue ultimately forfeited the construction permit in 1962. The late 1960s also saw the station begin to do some of its own news reporting of demonstrations that were taking place on the campus; the times also inspired a series of new programs on race relations and birth control. However, its programming continued to focus on education and shows for
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5292-535: The Tribune specified operation on 47.1 MHz, and the call sign W71SB. However, W71SB's co-ownership with the Tribune resulted in a delay, after the FCC began an investigation as to whether newspaper ownership of radio stations should be restricted. Thus, W71SB was one of six stations that was under the stipulation "that no construction facilities shall be undertaken or completed until the Commission has acted on
5418-431: The electrolytic detector and thermionic diode ( Fleming valve ) were invented by Reginald Fessenden and John Ambrose Fleming , respectively. Most important, in 1904–1906 the crystal detector , the simplest and cheapest AM detector, was developed by G. W. Pickard . Homemade crystal radios spread rapidly during the next 15 years, providing ready audiences for the first radio broadcasts. One limitation of crystals sets
5544-600: The " Golden Age of Radio ". The station moved to 1360 kHz in 1934, with a power of 500 watts. In 1940, WSBT moved again, to 930 kHz, which ended its timesharing with WGES in Chicago on its old frequency. One condition of this reassignment was that the Tribune end operation of a companion station, WFAM on 1200 kHz. With the implementation of North American Regional Broadcasting Agreement (NARBA) in March 1941, stations on 930 kHz, including WSBT, moved to 960 kHz. In 1942
5670-430: The " capture effect " means that the dominant signal needs to only be about twice as strong as the interfering one. To allow room for more stations on the mediumwave broadcast band in the United States, in June 1989 the FCC adopted a National Radio Systems Committee (NRSC) standard that limited maximum transmitted audio bandwidth to 10.2 kHz, limiting occupied bandwidth to 20.4 kHz. The former audio limitation
5796-425: The "mature, enriched adult", including classical music selections. Several early WBAA alumni went on to other broadcast roles, locally and nationally. Durwood Kirby 's lengthy broadcasting and media career got its start at WBAA in the early 1930s. Dick Shively, who was a sportscaster in the late 1930s, owned television stations in several Midwestern states, including WLFI-TV in Lafayette. Chris Schenkel went on to
5922-625: The 1920s, WSBT was assigned to various transmitting frequencies, until November 11, 1928, when, as part of a nationwide reallocation under the provisions of the Federal Radio Commission 's General Order 40 , the station was assigned to 1230 kHz on a timesharing basis with WFBM in Indianapolis and WCWK in Fort Wayne. Starting in 1932 WSBT was a CBS Radio Network affiliate , carrying dramas, comedies, news, sports, soap operas , game shows and big band broadcasts during
6048-603: The 1930s, most of the major radio stations in the country were affiliated with networks owned by two companies, NBC and CBS . In 1934, a third national network, the Mutual Radio Network , was formed as a cooperative owned by its stations. A second country which quickly adopted network programming was the United Kingdom, and its national network quickly became a prototype for a state-managed monopoly of broadcasting. A rising interest in radio broadcasting by
6174-660: The 1940s two new broadcast media, FM radio and television , began to provide extensive competition with the established broadcasting services. The AM radio industry suffered a serious loss of audience and advertising revenue, and coped by developing new strategies. Network broadcasting gave way to format broadcasting: instead of broadcasting the same programs all over the country, stations individually adopted specialized formats which appealed to different audiences, such as regional and local news, sports, "talk" programs, and programs targeted at minorities. Instead of live music, most stations began playing less expensive recorded music. In
6300-478: The 1989 season, making WBAA the last university radio station in the Big Ten to still carry its team's games; in 1990, syndicator Raycom Sports dropped WBAA from the network in order to give it increased flexibility with commercial inventory. However, WBAA continued to air smaller sports events, such as women's basketball. A 1982 windstorm toppled one of the three towers used at night and twisted another requiring
6426-532: The AM radio industry in the United States developed technology for broadcasting in stereo . Other nations adopted AM stereo, most commonly choosing Motorola's C-QUAM, and in 1993 the United States also made the C-QUAM system its standard, after a period allowing four different standards to compete. The selection of a single standard improved acceptance of AM stereo , however overall there was limited adoption of AM stereo worldwide, and interest declined after 1990. With
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#17327808002436552-531: The British public pressured the government to reintroduce the service, following its suspension in 1920. However, the government also wanted to avoid what it termed the "chaotic" U.S. experience of allowing large numbers of stations to operate with few restrictions. There were also concerns about broadcasting becoming dominated by the Marconi company. Arrangements were made for six large radio manufacturers to form
6678-609: The FM upgrade in 2009, WBAA-FM also debuted HD Radio, initially using an HD2 subchannel to rebroadcast WXPN in Philadelphia . The most recent signal improvement came in 2016, when the AM station added an FM translator at 105.9 MHz, a 220-watt facility that enables FM reception of the AM service in the immediate Lafayette area and within campus buildings where AM signals had been poorly received. In 2016, WBAA announced it planned to remove This American Life from its schedule after
6804-546: The PubJazz service as well as a Saturday night block of several specialty shows. Experimentation in radio—then commonly known as "wireless telegraphy"—at Purdue University dated back to at least 1910, but initial attempts to construct a transmitter capable of communicating with other stations had limited success. A more ambitious effort in 1916, based at the Electrical laboratory, had to be suspended in early 1917, when, with
6930-465: The Purdue board of trustees and subsequently by the FCC. In February 2022, the deal was filed with the FCC; the stations would be sold to MIPM along with a $ 500,000 commitment over two years for initial operating costs, while MIPM would give Purdue $ 700,000 in underwriting announcements over a 10-year period and $ 300,000 in paid student internships to Purdue students as well as nominal lease fees for WBAA's studios and transmission facilities. Integration with
7056-411: The Twenties when radio exploded can't know what it meant, this milestone for mankind. Suddenly, with radio, there was instant human communication. No longer were our homes isolated and lonely and silent. The world came into our homes for the first time. Music came pouring in. Laughter came in. News came in. The world shrank, with radio. The idea of broadcasting — the unrestricted transmission of signals to
7182-556: The U.S., for example) subject to international agreements. WSBT (AM) WSBT (960 kHz , "Sports Radio 96.1") is a commercial radio station in South Bend, Indiana , which airs a sports radio format . It is owned by Mid-West Family Broadcasting , with studios and offices on East Monroe Street in downtown South Bend. WSBT broadcasts at 5,000 watts , using different day and night directional antenna patterns to protect other stations on AM 960 . The transmitter site
7308-694: The United States and France this led to a small market of receiver lines geared for jewelers who needed accurate time to set their clocks, including the Ondophone in France, and the De Forest RS-100 Jewelers Time Receiver in the United States The ability to pick up time signal broadcasts, in addition to Morse code weather reports and news summaries, also attracted the interest of amateur radio enthusiasts. It
7434-610: The WBAA stations began in 2000. That year, a $ 1.5 million expansion of the studios was approved by Purdue's board of trustees in lieu of relocating them to the South Campus where a fine arts center was being built. In 2008, the FM station was approved to increase power to the present 14,000 watts. The change came as an equipment renovation was already planned; the AM station began broadcasting in HD Radio that December, and after
7560-466: The WFYI stations would come in the form of some WBAA programs being broadcast to WFYI listeners as well as WBAA members gaining access to PBS Passport from WFYI TV . The sale was finalized on June 30, 2022. Joint WBAA WBAA-FM AM broadcasting The earliest experimental AM transmissions began in the early 1900s. However, widespread AM broadcasting was not established until the 1920s, following
7686-595: The YMCA building, which was first licensed on April 29, 1922, and deleted on November 7, 1922. WGAZ made its formal debut broadcast starting at 7:30 p.m. on July 3, 1922. The program, "given through the courtesy of the Ries Furniture Company", featured local musical performers. On September 9, 1925, the call letters became WSBT, reflecting its ownership by the South Bend Tribune . Throughout
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#17327808002437812-523: The antenna wire. This meant that the full transmitter power flowed through the microphone, and even using water cooling, the power handling ability of the microphones severely limited the power of the transmissions. Ultimately only a small number of large and powerful Alexanderson alternators would be developed. However, they would be almost exclusively used for long-range radiotelegraph communication, and occasionally for radiotelephone experimentation, but were never used for general broadcasting. Almost all of
7938-482: The audience has continued to decline. In 1987, the elimination of the Fairness Doctrine requirement meant that talk shows, which were commonly carried by AM stations, could adopt a more focused presentation on controversial topics, without the distraction of having to provide airtime for any contrasting opinions. In addition, satellite distribution made it possible for programs to be economically carried on
8064-440: The call letters becoming WNSN, as "Sunny 101.5". As network programming moved to TV, WSBT switched to a full service middle of the road format of popular music, news and sports. When music listening switched from AM to FM, WSBT began adding more talk programming and reducing music. By the 1990s, the station was all talk, sports and news. Then as the station moved through the 2010s, WSBT shifted to more sports programming, with
8190-442: The call letters were changed again, to WSBT-FM. This original WSBT-FM discontinued operations at midnight on January 31, 1950, and turned its license in for cancellation. Station manager Robert H. Swinrz noted that, a year after WSBT-FM had begun fulltime duplication of WSBT programming, "a survey had shown that only a comparatively few radio owners have facilities for FM reception and only a negligible number listen to FM for more than
8316-473: The call sign of 9YA, which was changed the next year to 9YB. 9YB's primary transmitter was a 2-kilowatt spark set, which transmitted on wavelengths of 200 meters (1500 kHz) and 375 meters (800 kHz) and could only send the dots-and-dashes of Morse code . It was employed to send and receive messages between Purdue and other stations around the Midwest. The Purdue Exponent newspaper used 9YB as part of
8442-404: The characteristics of arc-transmitters . Fessenden attempted to sell this form of radiotelephone for point-to-point communication, but was unsuccessful. Fessenden's work with high-frequency spark transmissions was only a temporary measure. His ultimate plan for creating an audio-capable transmitter was to redesign an electrical alternator , which normally produced alternating current of at most
8568-403: The commission estimated that fewer than 250 AM stations were transmitting hybrid mode signals. On October 27, 2020, the FCC voted to allow AM stations to eliminate their analog transmissions and convert to all-digital operation, with the requirement that stations making the change had to continue to make programming available over "at least one free over-the-air digital programming stream that
8694-475: The continued migration of AM stations away from music to news, sports, and talk formats, receiver manufacturers saw little reason to adopt the more expensive stereo tuners, and thus radio stations have little incentive to upgrade to stereo transmission. In countries where the use of directional antennas is common, such as the United States, transmitter sites consisting of multiple towers often occupy large tracts of land that have significantly increased in value over
8820-437: The continuous wave AM transmissions made prior to 1915 were made by versions of the arc converter transmitter, which had been initially developed by Valdemar Poulsen in 1903. Arc transmitters worked by producing a pulsating electrical arc in an enclosed hydrogen atmosphere. They were much more compact than alternator transmitters, and could operate on somewhat higher transmitting frequencies. However, they suffered from some of
8946-434: The decades, to the point that the value of land exceeds that of the station itself. This sometimes results in the sale of the transmitter site, with the station relocating to a more distant shared site using significantly less power, or completely shutting down operations. The ongoing development of alternative transmission systems, including Digital Audio Broadcasting (DAB), satellite radio, and HD (digital) radio, continued
9072-567: The decline of the popularity of the traditional broadcast technologies. These new options, including the introduction of Internet streaming, particularly resulted in the reduction of shortwave transmissions, as international broadcasters found ways to reach their audiences more easily. In 2022 it was reported that AM radio was being removed from a number of electric vehicle (EV) models, including from cars manufactured by Tesla, Audi, Porsche, BMW and Volvo, reportedly due to automakers concerns that an EV's higher electromagnetic interference can disrupt
9198-440: The dedication ceremony of Ross–Ade Stadium in 1924 and Purdue– Indiana basketball games. After more transmitting frequencies became available, WBAA was reassigned to 1060 kHz in 1924, which was changed the next year to 1100 kHz. By 1926, the station's broadcasting schedule was 7:15 to 8:15 p.m. on Mondays, Wednesdays, and Fridays, with test transmissions as experimental station 9XY after midnight on Saturdays. Power
9324-569: The demonstration witnesses, which stated "[Radio] Telephony is admirably adapted for transmitting news, stock quotations, music, race reports, etc. simultaneously over a city, on account of the fact that no wires are needed and a single apparatus can distribute to ten thousand subscribers as easily as to a few. It is proposed to erect stations for this purpose in the large cities here and abroad." However, other than two holiday transmissions reportedly made shortly after these demonstrations, Fessenden does not appear to have conducted any radio broadcasts for
9450-656: The development of vacuum tube receivers and transmitters. AM radio remained the dominant method of broadcasting for the next 30 years, a period called the " Golden Age of Radio ", until television broadcasting became widespread in the 1950s and received much of the programming previously carried by radio. Later, AM radio's audiences declined greatly due to competition from FM ( frequency modulation ) radio, Digital Audio Broadcasting (DAB), satellite radio , HD (digital) radio , Internet radio , music streaming services , and podcasting . Compared to FM or digital transmissions , AM transmissions are more expensive to transmit due to
9576-443: The end of January 1930 after more than 10 months of silence; the facility was prepared to broadcast with 1,000 watts if the opportunity ever presented itself. Purdue also successfully applied to begin broadcasts with 1,000 watts during daylight hours. WCMA ceased broadcasts in 1932, with its time going to WKBF, which also purchased its assets. WKBF was allowed to use the frequency on a full-time basis from late May to October, when Purdue
9702-403: The entry of the United States into World War I, most civilian stations were ordered to shut down. During the war, Purdue conducted radio instruction for students and military personnel. After the end of the war, civilian radio stations were again permitted. In 1919, the university was issued a temporary authorization, followed by a "Technical and Training School" license which was originally given
9828-600: The expectation is that listeners will primarily be tuning into the FM signal rather than the nominally "primary" AM station. A 2020 review noted that "for many owners, keeping their AM stations on the air now is pretty much just about retaining their FM translator footprint rather than keeping the AM on the air on its own merits". In 2018 the FCC, led by then-Commission Chairman Ajit Pai , proposed greatly reducing signal protection for 50 kW Class A " clear channel " stations. This would allow co-channel secondary stations to operate with higher powers, especially at night. However,
9954-445: The fall of 1900, he successfully transmitted speech over a distance of about 1.6 kilometers (one mile), which appears to have been the first successful audio transmission using radio signals. However, at this time the sound was far too distorted to be commercially practical. For a time he continued working with more sophisticated high-frequency spark transmitters, including versions that used compressed air, which began to take on some of
10080-401: The first time. Music came pouring in. Laughter came in. News came in. The world shrank, with radio. Following World War I, the number of stations providing a regular broadcasting service greatly increased, primarily due to advances in vacuum-tube technology. In response to ongoing activities, government regulators eventually codified standards for which stations could make broadcasts intended for
10206-432: The former WRM in Illinois. Broadcasting on the new dial position began that August. That fall, it broadcast for four and a half hours a day, six days a week. As early as 1937, Purdue filed to relocate the transmitter and increase daytime power to 5,000 watts. The first proposal involved relocating the transmitter to a more central location in the state and establishing a studio in Indianapolis, as well as converting WBAA into
10332-450: The general newspaper-ownership question". On June 9, 1941, W71SB's construction permit was reinstated, pending the outcome of the newspaper ownership review, and the station began broadcasting in May 1943. The FCC later modified its rules for FM station call signs, and on November 1, 1943, W71SB became WSBF. After the FM band was moved to 88-108 MHz, WSBF was reassigned to 101.3 MHz. In 1949
10458-624: The general public, for example, in the United States formal recognition of a "broadcasting service" came with the establishment of regulations effective December 1, 1921, and Canadian authorities created a separate category of "radio-telephone broadcasting stations" in April 1922. However, there were numerous cases of entertainment broadcasts being presented on a regular schedule before their formal recognition by government regulators. Some early examples include: Because most longwave radio frequencies were used for international radiotelegraph communication,
10584-417: The general public, or to have even given additional thought about the potential of a regular broadcast service, and in a 1908 article providing a comprehensive review of the potential uses for his radiotelephone invention, he made no references to broadcasting. Because there was no way to amplify electrical currents at this time, modulation was usually accomplished by a carbon microphone inserted directly in
10710-554: The isolation of rural life. Political officials could now speak directly to millions of citizens. One of the first to take advantage of this was American president Franklin Roosevelt , who became famous for his fireside chats during the Great Depression . However, broadcasting also provided the means to use propaganda as a powerful government tool, and contributed to the rise of fascist and communist ideologies. In
10836-411: The lack of any way to amplify the signals meant they were somewhat weak. On December 21, 1906, Fessenden made an extensive demonstration of the new alternator-transmitter at Brant Rock, Massachusetts, showing its utility for point-to-point wireless telephony, including interconnecting his stations to the wire telephone network. As part of the demonstration, speech was transmitted 18 kilometers (11 miles) to
10962-419: The late 1960s and 1970s, top 40 rock and roll stations in the U.S. and Canada such as WABC and CHUM transmitted highly processed and extended audio to 11 kHz, successfully attracting huge audiences. For young people, listening to AM broadcasts and participating in their music surveys and contests was the social media of the time. In the late 1970s, spurred by the exodus of musical programming to FM stations,
11088-432: The local business community in 1996, seeking financial support to return NPR output to the WBAA stations. The simultaneous threat of federal cuts to public broadcasting led WBAA to start its first-ever pledge drive that fall. In June 1997, Purdue received enough financial support from listeners to return WBAA to NPR after nearly five years away. 24-hour broadcasting began on FM in 1994 and on AM in 1998. Internet streaming of
11214-399: The marketplace decide" which was best. The lack of a common standard resulted in consumer confusion and increased the complexity and cost of producing AM stereo receivers. In 1993, the FCC again revised its policy, by selecting C-QUAM as the sole AM stereo implementation. In 1993, the FCC also endorsed, although it did not make mandatory, AMAX broadcasting standards that were developed by
11340-432: The message, spreading it broadcast to receivers in all directions". However, it was recognized that this would involve significant financial issues, as that same year The Electrician also commented "did not Prof. Lodge forget that no one wants to pay for shouting to the world on a system by which it would be impossible to prevent non-subscribers from benefiting gratuitously?" On January 1, 1902, Nathan Stubblefield gave
11466-410: The mid-1950s. In 1959, Purdue filed for and received a construction permit to expand its service to FM on 99.1 MHz. The university wanted to improve its nighttime service, which due to the nature of the AM operation was directional and had poor reception going any direction other than north from Lafayette. However, work was delayed on the project because Purdue engineering resources were diverted to
11592-448: The multiple incompatible AM stereo systems, and failure of the manufacturers (including the auto makers) to effectively promote AMAX radios, coupled with the ever-increasing background of noise in the band, the general public soon lost interest and moved on to other media. On June 8, 1988, an International Telecommunication Union (ITU)-sponsored conference held at Rio de Janeiro, Brazil adopted provisions, effective July 1, 1990, to extend
11718-537: The necessity of having to transmit a high power carrier wave to overcome ground losses, and the large antenna radiators required at the low broadcast frequencies, but can be sent over long distances via the ionosphere at night; however, they are much more susceptible to interference, and often have lower audio fidelity. Thus, AM broadcasters tend to specialize in spoken-word formats, such as talk radio , all-news radio and sports radio , with music formats primarily for FM and digital stations. People who weren't around in
11844-405: The new frequencies. It was now estimated that the expanded band could accommodate around 300 U.S. stations. However, it turned out that the number of possible station reassignments was much lower, with a 2006 accounting reporting that, out of 4,758 licensed U.S. AM stations, only 56 were now operating on the expanded band. Moreover, despite an initial requirement that by the end of five years either
11970-428: The new policy, by 2011 there were approximately 500 in operation, and as of 2020 approximately 2,800 of the 4,570 licensed AM stations were rebroadcasting on one or more FM translators. In 2009 the FCC stated that "We do not intend to allow these cross-service translators to be used as surrogates for FM stations". However, based on station slogans, especially in the case of recently adopted musical formats, in most cases
12096-418: The new regulations, the university applied for a broadcasting station license, which was issued on April 5, 1922, with the call letters WBAA, for operation on the 360-meter "entertainment" wavelength. 9YB continued in use for experimental and amateur transmissions. Although not the first Indiana station to receive a broadcasting license, WBAA is the oldest surviving one. (Another contender, WSBT in South Bend ,
12222-411: The original station or its expanded band counterpart had to cease broadcasting, as of 2015 there were 25 cases where the original standard band station was still on the air, despite also operating as an expanded band station. HD Radio is a digital audio broadcasting method developed by iBiquity . In 2002 its "hybrid mode", which simultaneously transmits a standard analog signal as well as a digital one,
12348-433: The overheating issues of needing to insert microphones directly in the transmission antenna circuit. Vacuum tube transmitters also provided high-quality AM signals, and could operate on higher transmitting frequencies than alternator and arc transmitters. Non-governmental radio transmissions were prohibited in many countries during World War I, but AM radiotelephony technology advanced greatly due to wartime research, and after
12474-441: The primary early developer of AM technology is Canadian-born inventor Reginald Fessenden . The original spark-gap radio transmitters were impractical for transmitting audio, since they produced discontinuous pulses known as " damped waves ". Fessenden realized that what was needed was a new type of radio transmitter that produced steady "undamped" (better known as " continuous wave ") signals, which could then be "modulated" to reflect
12600-409: The radio station among the general audience. It also rounded out a station that was in its 50th year of providing a varied service: courses for Purdue University credit, a late evening rock show, educational programming syndicated to dozens of stations nationwide, and the origination of Purdue football broadcasts to 13 commercial stations across Indiana. The football games continued on the station through
12726-650: The reception of AM transmissions and hurt the listening experience, among other reasons. However the United States Congress has introduced a bill to require all vehicles sold in the US to have an AM receiver to receive emergency broadcasts. The FM broadcast band was established in 1941 in the United States, and at the time some suggested that the AM band would soon be eliminated. In 1948 wide-band FM's inventor, Edwin H. Armstrong , predicted that "The broadcasters will set up FM stations which will parallel, carry
12852-799: The same deficiencies. The lack of any means to amplify electrical currents meant that, like the alternator transmitters, modulation was usually accomplished by a microphone inserted directly in the antenna wire, which again resulted in overheating issues, even with the use of water-cooled microphones. Thus, transmitter powers tended to be limited. The arc was also somewhat unstable, which reduced audio quality. Experimenters who used arc transmitters for their radiotelephone research included Ernst Ruhmer , Quirino Majorana , Charles "Doc" Herrold , and Lee de Forest . Advances in vacuum tube technology (called "valves" in British usage), especially after around 1915, revolutionized radio technology. Vacuum tube devices could be used to amplify electrical currents, which overcame
12978-400: The same program, as over their AM stations... eventually the day will come, of course, when we will no longer have to build receivers capable of receiving both types of transmission, and then the AM transmitters will disappear." However, FM stations actually struggled for many decades, and it was not until 1978 that FM listenership surpassed that of AM stations. Since then the AM band's share of
13104-455: The show announced plans to add Pandora as a distributor, a decision general manager Mike Savage panned as unprincipled and troubling for public radio. The announcement met with poor reception from listeners, and WBAA dropped the plan within days. In July 2021, Purdue University announced plans to transfer WBAA management to Metropolitan Indianapolis Public Media (MIPM), the owner of WFYI radio and television in Indianapolis, pending approval by
13230-410: The sounds being transmitted. Fessenden's basic approach was disclosed in U.S. Patent 706,737, which he applied for on May 29, 1901, and was issued the next year. It called for the use of a high-speed alternator (referred to as "an alternating-current dynamo") that generated "pure sine waves" and produced "a continuous train of radiant waves of substantially uniform strength", or, in modern terminology,
13356-563: The station began to broadcast the "Purdue University School of the Air", radio school programming that by 1952 was being listened to by 275,000 schoolchildren in Indiana and neighboring states; this continued until 1968. There were adult education courses, coverage of Purdue and West Lafayette High School sporting events, and market reports, broadcast from a station with 16 staff and 35 student staffers. WBAA began to distribute tapes of its programming to other commercial and noncommercial broadcasters in
13482-485: The station to temporarily broadcast with reduced power after sunset; all three masts were replaced. Thirty years after its first attempt, Purdue filed again in 1989 to build a new radio station on the FM band in West Lafayette, with another channel allocated to the area at the university's request. The FCC approved the application for WBAA-FM in 1991, with the intention to create a musically oriented FM service and
13608-681: The talk shows reduced. Schurz Communications announced on September 14, 2015, that it would exit broadcasting and sell its television and radio stations, including WSBT, to Gray Television for $ 442.5 million. The sale, which ended 93 years of ownership by the company, separated WSBT radio from both the South Bend Tribune (which Schurz initially kept), and WSBT-TV (which was sold separately due to Gray's existing ownership of WNDU-TV ). Though Gray initially intended to keep Schurz' radio stations, on November 2, it announced that Mid-West Family Broadcasting would acquire WSBT and Schurz' other South Bend radio stations for $ 5.5 million. The sale to Mid-West
13734-411: The technology for AM broadcasting in stereo was challenging due to the need to limit the transmissions to a 20 kHz bandwidth, while also making the transmissions backward compatible with existing non-stereo receivers. In 1990, the FCC authorized an AM stereo standard developed by Magnavox, but two years later revised its decision to instead approve four competing implementations, saying it would "let
13860-508: The time, adopted a regulation formally establishing a broadcasting station category, which set aside the wavelength of 360 meters (833 kHz) for entertainment broadcasts, and 485 meters (619 kHz) for farm market and weather reports. On June 29, 1922, the South Bend Tribune was issued a license for a new station on the shared 360 meter "entertainment" wavelength. The original call letters, WGAZ, were randomly assigned from
13986-401: The translator stations are not permitted to originate programming when the "primary" AM station is broadcasting, they are permitted to do so during nighttime hours for AM stations licensed for daytime-only operation. Prior to the adoption of the new policy, as of March 18, 2009, the FCC had issued 215 Special Temporary Authority grants for FM translators relaying AM stations. After creation of
14112-522: The transmitter power was increased to 1,000 watts, and in 1947 WSBT increased its power to the current 5,000-watt output. There have been two different FM stations that have had the call letters WSBT-FM. On May 24, 1940, the Federal Communications Commission (FCC) announced the establishment, effective January 1, 1941, of an FM radio band operating on 40 channels spanning 42–50 MHz. The Construction Permit assigned to
14238-496: The upper end of the Region 2 AM broadcast band, by adding ten frequencies which spanned from 1610 kHz to 1700 kHz. At this time it was suggested that as many as 500 U.S. stations could be assigned to the new frequencies. On April 12, 1990, the FCC voted to begin the process of populating the expanded band, with the main priority being the reduction of interference on the existing AM band, by transferring selected stations to
14364-548: The war the availability of tubes sparked a great increase in the number of amateur radio stations experimenting with AM transmission of news or music. Vacuum tubes remained the central technology of radio for 40 years, until transistors began to dominate in the late 1950s, and are still used in the highest power broadcast transmitters. Unlike telegraph and telephone systems, which used completely different types of equipment, most radio receivers were equally suitable for both radiotelegraph and radiotelephone reception. In 1903 and 1904
14490-404: The youngest demographic groups. Among persons aged 12–24, AM accounts for only 4% of listening, while FM accounts for 96%. Among persons aged 25–34, AM accounts for only 9% of listening, while FM accounts for 91%. The median age of listeners to the AM band is 57 years old, a full generation older than the median age of FM listeners." In 2009, the FCC made a major regulatory change, when it adopted
14616-572: Was 15 kHz resulting in bandwidth of 30 kHz. Another common limitation on AM fidelity is the result of receiver design, although some efforts have been made to improve this, notably through the AMAX standards adopted in the United States. AM broadcasts are used on several frequency bands. The allocation of these bands is governed by the ITU 's Radio Regulations and, on the national level, by each country's telecommunications administration (the FCC in
14742-474: Was approved by the FCC for use by AM stations, initially only during daytime hours, due to concerns that during the night its wider bandwidth would cause unacceptable interference to stations on adjacent frequencies. In 2007 nighttime operation was also authorized. The number of hybrid mode AM stations is not exactly known, because the FCC does not keep track of the stations employing the system, and some authorized stations have later turned it off. But as of 2020
14868-600: Was consummated on February 16, 2016. On January 10, 1994, WSBT Radio debut a daily sports talk show with Tom Denin and John Fineran. Today the show airs from 5-7pm(ET) with Darin Pritchett as the host. The show focus on local sports, specifically Notre Dame athletics. On March 30, 2012, WSBT began broadcasting on an FM translator (W241AD) at 96.1 MHz in South Bend. The translator had previously been owned and operated by Friends of Christian Radio, Inc. and repeated
14994-400: Was immediately recognized that, much like the telegraph had preceded the invention of the telephone, the ability to make audio radio transmissions would be a significant technical advance. Despite this knowledge, it still took two decades to perfect the technology needed to make quality audio transmissions. In addition, the telephone had rarely been used for distributing entertainment, outside of
15120-408: Was in store for the old one; on March 29, WBAA moved from 890 to 920 kHz, along with all stations on that frequency, as part of the frequency reorganization of NARBA . Broadcasting began with the 5,000-watt facility on September 27; the site included three 265-foot (81 m) towers to support the directional antenna pattern used at night. WBAA's educational service was also increasing. In 1944,
15246-435: Was not licensed until late June 1922.) The WBAA call sign was randomly assigned from a sequential list of available call letters and was one of the first four-letter call signs issued to a broadcasting station, as most earlier stations had received three-letter assignments. The earliest reported broadcast as WBAA was made on April 21, 1922, of an Arbor Day message prepared by Secretary of Agriculture Henry C. Wallace , that
15372-431: Was on summer break. The station was rebuilt in 1933; all of the equipment was built on the Purdue campus. The large water-cooled transmitter, on the top floor of the Electrical Engineering Building, was in a space so inadequately ventilated that engineer Ralph Townsley wondered why it never burned up. In 1934, the FRC granted full time to WKBF and moved WBAA to a new frequency, 890 kHz, which it would share with WILL ,
15498-516: Was raised to 500 watts, by which time the station was airing the full slate of Purdue home basketball games. The Federal Radio Commission (FRC), formed in 1927, downgraded the nighttime power of a University of Illinois station, WRM, from 1,000 to 500 watts, and ordered it to share WBAA's frequency. On November 11, 1928, with the implementation of the FRC's General Order 40 , WBAA was reassigned to 1400 kHz, sharing time with two other Indiana stations: Culver Military Academy 's WCMA, and WKBF ,
15624-564: Was read over numerous stations across the United States. Much of the output from WBAA in its early years consisted of talks from Purdue's agricultural extension and engineering departments. These included such discussions as "The Hot School Dinner", "Home Canning of Meats", "Bread from Indiana Flour", and "Elimination of Smoke, Dust, and Fumes in Industrial Processes". Also broadcast by the station were livestock reports from Chicago's market and broadcasts of Purdue sports, such as
15750-473: Was the first organization to create a radio network, and also to promote commercial advertising, which it called "toll" broadcasting. Its flagship station, WEAF (now WFAN) in New York City, sold blocks of airtime to commercial sponsors that developed entertainment shows containing commercial messages . AT&T held a monopoly on quality telephone lines, and by 1924 had linked 12 stations in Eastern cities into
15876-406: Was the lack of amplifying the signals, so listeners had to use earphones , and it required the development of vacuum-tube receivers before loudspeakers could be used. The dynamic cone loudspeaker , invented in 1924, greatly improved audio frequency response over the previous horn speakers, allowing music to be reproduced with good fidelity. AM radio offered the highest sound quality available in
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