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.
85-548: WKXL (1450 AM ) is a radio station broadcasting a talk radio format. Licensed to Concord, New Hampshire , United States, the station serves the Concord area. The station is currently owned by New Hampshire Family Radio LLC, itself owned by former Senator Gordon J. Humphrey , and features programming from AP Radio and Bloomberg Radio . On December 6, 1945, the Federal Communications Commission (FCC) issued
170-465: 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
255-841: 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
340-557: 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
425-596: 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
510-617: 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
595-438: A construction permit to Charles M. Dale , then the sitting Governor of New Hampshire , for a new 250-watt radio station on 1450 kHz in Concord. The station signed on June 15, 1946, with studios in the historic Eagle Hotel and an adjoining building. After five years, Dale sold WKXL to Capitol Broadcasting Corporation, a consortium formed by part-owners of WFEA at Manchester , for $ 50,000 in 1951. Under Capitol ownership,
680-552: 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
765-568: 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
850-463: 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
935-512: 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
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#17328800033781020-469: 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
1105-479: 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)
1190-503: 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
1275-399: 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
1360-482: 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
1445-423: 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
1530-452: 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
1615-427: 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
1700-631: A transaction valued at $ 1.5 million. WKXL-FM was largely a repeater of the 1450 AM broadcast until 1986, when the owners launched a "light alternative" adult album alternative format; this format ended in 1991, when financial pressures returned the FM signal to a simulcast of the AM broadcast. Music programming on the stations ended altogether in 1995, as their adult contemporary format gave way to news, talk , and sports . In 1999, WKXL and its sister stations were sold by their employee-owners to Vox Media Group. Major cutbacks in programming followed, including
1785-461: 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'
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#17328800033781870-406: 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
1955-497: 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
2040-645: 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
2125-556: 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
2210-615: 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
2295-479: 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
2380-431: 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
2465-430: 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
2550-587: 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
2635-660: 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
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2720-528: 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
2805-521: 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
2890-578: The Fisher Cats remained on WKXL. WKXL began airing on FM translator W280EC (103.9 FM) in the early 2010s. In 2014, the station acquired it outright from New Hampshire Gospel Radio for $ 5,000. Several WKXL broadcasters have been honored by the New Hampshire Association of Broadcasters as Broadcaster of the Year, including Frank Estes (1979), Dick Osborne (1981, 1989) and Jim Jeanotte (2012). Jeanotte
2975-400: The Fisher Cats. The station was acquired by former New Hampshire senator Gordon J. Humphrey , alongside business partner George Stevens, for $ 830,000 in 2004; former owner Bailey cited the sale as a "golden opportunity" even though he had owned the station just 18 months. The transaction separated WKXL from operational control of WTPL; Arnie Arnesen's talk show would move solely to WTPL, while
3060-605: The Ossippee/Conway area. The licensee for WANH, WJNH, and WVNH is New Hampshire Gospel Radio, Inc. The board of directors are; John Loker; George Dykstra, Treasurer; Peter J. Stohrer, Vice President; John Donovan, President; Janice Cyr, Secretary/Station Manager/Director; Judy Mason, Cheryl Eggert, Steve Blanchard, Mark Hendersen, Tom Marsh, Certified Public Accountant; and Roy McCandless, Attorney at Law. The studios for New Hampshire Gospel Radio Inc. (NHGR) are located at 10 Ferry Street STE #424. in Concord, NH. In addition to
3145-411: 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
3230-612: The U.S., for example) subject to international agreements. WVNH WVNH (91.1 FM ) is a radio station broadcasting a Christian radio format. Licensed to Concord, New Hampshire , United States, the station serves the Concord and Franklin areas. The station is currently owned by New Hampshire Gospel Radio, Inc. Programming is simulcast on WANH (88.3 FM) in Meredith , serving the Lakes Region and on WJNH (91.1 FM) in Conway , serving
3315-662: 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
3400-535: The WKXL lineup, including a talk show hosted by Arnie Arnesen and New Hampshire Fisher Cats minor league baseball. WKXL-FM, not included in the sale, would retain WKXL's previous lineup under a new identity: WTPL . In 2003, WTPL would also come under Embro's control under a local marketing agreement ; Arnesen's program, which had been based at WNTK in Newport before relocating to Concord, would air on both stations, as would
3485-523: 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
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3570-474: 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
3655-494: The cancellation of the station's "Party Line" program and live broadcasts of the city council; ratings fell as a result. The FM simulcast would move from 102.3, repurposed as country music station WOTX, to WRCI (107.7) in 2000; the 102.3 FM signal is now broadcasting as WAKC . After three years, Vox sold the station to Warren Bailey, operations manager of WLNH-FM in Laconia ; under his ownership, more local programs were restored to
3740-404: 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
3825-403: 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
3910-475: 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
3995-437: 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
4080-429: The day, approved in 1961. The station expanded its service to FM when WKXL-FM 102.3, an 80 percent simulcast of the AM frequency and its middle of the road format, began broadcasting on March 7, 1972. In 1980, Estes, who had bought out Close, sold the WKXL stations to a consortium of seven station employees, continuing under the name Capitol Broadcasting Corporation, led by Dick Osborne, Don Shapiro and Pat Chaloux, in
4165-434: 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
4250-567: 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
4335-569: 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
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#17328800033784420-756: The early 1900s. However, widespread AM broadcasting was not established until the 1920s, following 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
4505-600: 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,
4590-445: 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
4675-401: 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
4760-620: 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,
4845-417: 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
4930-541: 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
5015-411: 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
5100-419: 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,
5185-399: 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
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#17328800033785270-432: 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
5355-448: 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
5440-537: 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
5525-405: 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
5610-428: 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
5695-411: 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,
5780-433: 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
5865-441: 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
5950-637: 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
6035-799: 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
6120-400: 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
6205-410: 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,
6290-757: The station became a CBS Radio affiliate from 1951 to 1959 and again beginning in December 1962. The original principals in Capitol sold the company to H. Scott Killgore, a 20-year radio veteran, for $ 75,000 in 1954. That same year, Tom Shovan, who would be instrumental in shaping the careers of Rick Dees and Laura Schlesinger , started his radio career as a disc jockey at WKXL; he was just 12 years old. Another sale followed three years later to Frank Estes and Joseph Close, owners of WKNE (1290 kHz) in Keene and WKNY in Kingston, New York . A power increase followed to 1,000 watts during
6375-411: 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
6460-401: 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
6545-492: 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
6630-548: 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
6715-404: 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
6800-565: 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
6885-591: Was also the long-time host of Granite State Challenge , a New Hampshire Public Television high school quizbowl program. Osborne was also recognized in 2004 by The New Hampshire Legends Hockey Hall of Fame, as WKXL broadcast University of New Hampshire Wildcats hockey for many years, along with other WKXL announcers Harvey Smith and Jim Rivers. Jeanotte was honored in 2012 by the University of New Hampshire for his work on UNH sports broadcasts. AM broadcasting The earliest experimental AM transmissions began in
6970-474: 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
7055-400: 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
7140-468: 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
7225-406: 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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