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.
119-613: KMOX (1120 AM ) is a commercial radio station in St. Louis, Missouri . Owned by Audacy, Inc. , it is a 50,000 watt Class A clear-channel station with a non-directional signal . The KMOX studios and offices are on Olive Street at Tucker Boulevard in the Park Pacific Building in St. Louis. KMOX refers to itself as "NewsRadio 1120 - The Voice of St. Louis". It is considered the first U.S. station to program all talk shows around
238-472: 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
357-846: 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
476-471: A band of frequencies, from 550 to 1500 kHz, had been established, with higher-powered stations, known as "Class B", assigned to the frequencies from 550 to 1070, while lower-powered "Class A" stations were assigned to 1080 to 1500. In 1926, the government's regulatory authority under the 1912 Radio Act was successfully challenged, and, for a chaotic period that lasted until early 1927, radio stations were free to use any frequency and power they chose, while
595-602: A blank Elimination Notes entry were found to meet the new "convenience, interest, and necessity" standard, and were relicensed. Most of the challenged stations submitted documentation or made presentations supporting their relicensing, and a majority were approved, although often with a power reduction. However, on July 27 the FRC announced that 36 stations had failed to present justifications supporting their applications, thus would be deleted as of August 1, 1928. In addition, four stations voluntarily surrendered their licenses. Through
714-570: 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
833-610: 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
952-635: 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
1071-564: 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
1190-580: 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
1309-463: 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
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#17327905586141428-516: A high-pitched "heterodyne" tone that interfered with the reception of both stations. Secondly, directional antennas would not be developed until the first installation at WFLA-WSUN in Tampa, Florida in early 1932, so there was no effective method for limiting signals in a given direction. An additional requirement was that the station assignments meet the standards of the Davis Amendment ,
1547-516: 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
1666-474: 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
1785-487: 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)
1904-506: 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
2023-417: A nationally syndicated program with several dozen stations airing it across the country. The syndication was discontinued in 2017, but the show continued to air late nights on KMOX. On February 2, 2017, CBS Radio announced it would merge with Entercom . The merger was approved on November 9, 2017, and was consummated on November 17. The Entercom acquisition ended KMOX's 88 years of CBS ownership. KMOX held
2142-438: A new studio and office facility in downtown St. Louis to house KMOX-AM-FM-TV, which until that point had been operating from separate locations. The radio stations had been headquartered near Forest Park . KMOX-TV moved from Cole Street into the new facility, known as One Memorial Drive. As network programming shifted from radio to television in the 1950s, KMOX scheduled a full service format of talk shows, news, and middle of
2261-399: 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
2380-486: 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
2499-639: A provision attached to the March 28, 1928 reauthorization of the Radio Act of 1927 , which mandated an "equality of radio broadcasting service" within the United States. It specified an "equitable allocation" among five regional zones, in addition to assignments proportional to population among the states within each zone. Following the establishment of the Federal Radio Commission, starting on May 3, 1927 existing stations were initially issued
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#17327905586142618-423: 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
2737-507: A series of temporary authorizations. The FRC conducted a review and census of the existing stations, then notified them that if they wished to remain on the air they had to file a formal license application by January 15, 1928, as the first step in determining whether they met the new "public interest, convenience, or necessity" standard. General Order 32 was used to notify 164 stations that they had been identified as questionable in meeting this new standard. The following, dated May 25, 1928,
2856-452: 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
2975-427: 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
3094-461: 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'
3213-598: Is a programmer with the Salem Radio Network . America in the Morning is supplied by Westwood One , a subsidiary of Cumulus Media . For the past 21 years, KMOX has hosted a holiday radio program, in which KMOX personalities perform an old-time radio show in front of a live audience. On March 22, 2021, KMOX added an FM simulcast on 98.7 FM K254CR, a translator formerly used for KFTK (AM) , then temporarily for KFTK-FM . This translator provides coverage to
3332-406: 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
3451-502: 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
3570-701: Is responsible for the activation of the Greater St. Louis Emergency Alert System for hazardous weather, disaster declarations, etc., and is the EAS primary entry point for eastern Missouri and southern Illinois. KMOX airs a talk radio format with blocks of news every morning and in weekday afternoon drive time . Middays it carries the Dave Glover Show, which replaced The Rush Limbaugh Show . Local talk hosts Charlie Brennan and Amy Marxkors are heard in late mornings and Mark Reardon in early afternoons. In
3689-645: 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
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3808-578: Is the flagship station of the St. Louis Cardinals Baseball team, and was the flagship station for the St. Louis Blues Hockey team through the 2018–2019 season. KMOX has a large team of local newscasters and reporters, and airs CBS News Radio at the beginning of most hours. KMOX also has an agreement to share news gathering and weather information with KMOV , the CBS television network affiliate for St. Louis. At one time, KMOX and KMOV (formerly KMOX-TV) were sister stations , both owned by CBS. KMOX
3927-411: Is the team's TV commentator today. Bill Wilkerson , the station's football caller, was the first black man to be the lead announcer for an NFL team when he took over commentary duties for the football Cardinals in 1973: three years later, he would assume the same position for Mizzou football, where once again he would be one of the first black primary broadcasters in major college athletics, only leaving
4046-578: 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
4165-625: 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
4284-493: 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
4403-485: The Federal Radio Commission (FRC), stations were initially issued a series of temporary authorizations starting on May 3, 1927. In addition, stations were informed that if they wanted to continue operating, they needed to file a formal license application by January 15, 1928, as the first step in determining whether they met the new "public interest, convenience, or necessity" standard. On May 25, 1928,
4522-519: The North American Regional Broadcasting Agreement . CBS had planned to have a corporate- owned and operated television station in St. Louis, to pair with KMOX. In 1957, the network originally won an FCC construction permit to build a new station on Channel 11, the last remaining commercial VHF channel in St. Louis. After being approached with an offer, CBS decided in August of that year to instead buy
4641-481: The Rush Limbaugh show weekdays for several decades. The program was sometimes pre-empted by St. Louis Cardinals ' afternoon baseball games. Limbaugh was one of the few non-local shows broadcast on the station; it was syndicated by Premiere Networks , a subsidiary of iHeartMedia . KMOX also carries two non-local shows overnight, Our American Stories with Lee Habeeb and America in the Morning . Habeeb
4760-604: The White House , a story carried nationally by CBS. Through the " Golden Age of Radio ," KMOX carried the CBS schedule of dramas, comedies, news, sports, soap operas, game shows and big band broadcasts. The studios and offices were housed in the Merchandise Mart Building on Washington Street. On March 29, 1941, KMOX moved from 1090 to 1120 kHz, its location ever since, as part of the implementation of
4879-431: 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
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4998-430: 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
5117-603: 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
5236-660: 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
5355-532: 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
5474-531: 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
5593-527: The FRC issued General Order 32 , which notified 164 stations, including KFQA, also in St. Louis, that "From an examination of your application for future license it does not find that public interest, convenience, or necessity would be served by granting it." KFQA proposed that instead of maintaining its own transmitting facility, it would share the facilities of an existing station. The FRC initially disapproved of this proposal, and ordered KFQA deleted, but eventually relented, and assigned KMOX to be operated under
5712-411: 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
5831-401: The U.S., for example) subject to international agreements. General Order 32 The Federal Radio Commission 's (FRC) General Order 32 , dated May 25, 1928, notified 164 of the over 600 existing U.S. radio stations that their applications for continued operation would be denied unless they showed that they met the FRC's "public interest, convenience, or necessity" standard. The result was
5950-694: 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
6069-523: 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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#17327905586146188-482: 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
6307-404: 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
6426-624: The clock. KMOX's transmitter is located off Route 162 in Pontoon Beach, Illinois . With a good radio, KMOX's nighttime signal can be heard across most of the United States and into Mexico and Canada. However, it is strongest in the Central United States. Its daytime signal provides at least secondary coverage to most of Eastern Missouri and much of Southern Illinois . The station is also heard on KEZK's HD2 subchannel and translator 98.7 K254CR. Along with WIL-FM , KMOX
6545-403: 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
6664-475: 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
6783-437: 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
6902-434: 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
7021-567: 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
7140-569: 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
7259-509: The distinction of holding the record for consecutive number one Arbitron ratings books in the United States. The station was consistently the top rated radio station in St. Louis since the ratings service began in 1972 until 2010, when WARH took over the top spot in the Arbs. KMOX remains the top rated AM station, consistently in the top ten in the Nielsen ratings for St. Louis. KMOX carried
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#17327905586147378-418: The dual call sign of KMOX-KFQA. On November 11, 1928, the FRC made a major reallocation of station transmitting frequencies, as part of a reorganization resulting from its implementation of General Order 40 . KMOX was designated a clear-channel station on 1090 kHz. In mid-1930, the dual call sign operation as KMOX-KFQA ended, and the station's call sign reverted to just KMOX. CBS bought KMOX, and began
7497-756: 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
7616-550: The elimination of more than 60 stations, plus numerous power reductions, that somewhat reduced the congestion of the broadcast band, in preparation for implementation of the General Order 40 reallocation later that year. Radio transmissions in the United States were originally regulated by the Department of Commerce , as authorized by the Radio Act of 1912 . The first formal regulations governing broadcasts intended for
7735-551: The end of August, the FRC announced additional stations that would be deleted, and those which would be relicensed. Stations designated for September 1 deletions included WCOT, WNBA, WJBA, WPEP and WTRL, and KWUC, WAIZ, WNAL. The deletion of KFQA in St. Louis Missouri was reported, although it was later consolidated with KMOX. A final report stated that WMBB-WOK would be deleted, while WQJ, WBCN, WLIB, KFKX, WGWB, WMBW, WBAO, WCLS, WLBO and five Nebraska stations were being consolidated with other stations. One additional station, WMBJ,
7854-510: The evening, the station airs sports. At night, local host Ryan Wrecker is heard, followed by two syndicated shows, Our American Stories with Lee Habeeb and America in the Morning . The Other Side of Midnight with Frank Morano is heard on Mondays in the early morning hours. On weekend mornings, all-news blocks start the schedule, followed by programs on money, health, car repair, home improvement and old time radio dramas and comedies. Some weekend shows are paid brokered programming . KMOX
7973-447: The existing KWK-TV for $ 4 million. KWK-TV was owned by a group including the publisher of the St. Louis Globe-Democrat . CBS took control of KWK-TV's operations that March, and changed its call letters to KMOX-TV, sharing the call sign with AM 1120. The original Viacom purchased KMOX-TV from CBS in 1986, and because of an FCC regulation in place then that prohibited TV and radio stations in
8092-648: 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,
8211-445: 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
8330-501: The first full-time talk radio station in the country, helping keep KMOX dominance in the St. Louis radio market for many decades. On February 29, 1960, Jack Buck hosted the first "At Your Service" program, which included an interview with former First Lady Eleanor Roosevelt . That program, like the sports and talk shows that soon followed, pioneered a format for radio featuring news maker interviews, guest appearances, and calls from listeners. After Hyland died in 1992, Rod Zimmerman
8449-401: 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
8568-438: The general public were adopted effective December 1, 1921. This initially established just two transmitting wavelengths — 360 meters (833 kHz) for "entertainment" broadcasts, and 485 meters (619 kHz) for "market news and weather reports". The number of broadcasting stations grew dramatically in 1922, reaching over 500 by the end of the year, and the government began making available additional frequencies. By November 1924
8687-624: 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,
8806-417: 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
8925-708: The granting of your application, it will be finally denied. The table below reviews the stations included in the General Order 32 notifications. The focus was on the most congested regions, especially around the Chicago and New York City areas. No stations from the sparsely populated Zone 3 were included. On the table, the Elimination Notes column records cases where stations were ultimately eliminated, either through deletion, by surrendering their licenses, or by consolidation with other stations. Stations with
9044-495: The inner ring suburbs of St. Louis. KMOX also added The Dave Glover Show to their schedule, which previously aired on KFTK for the past two years, and following Limbaugh's death elected to launch a new, local show hosted by longtime news reporter Carol Daniel in its lunchtime timeslot. KMOX has had a long history of broadcasting sports. In 1926, it aired the Cardinals-Yankees World Series , and starting
9163-554: 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
9282-411: 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
9401-419: 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,
9520-399: 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
9639-432: 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
9758-448: 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
9877-537: 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
9996-405: 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
10115-428: 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
10234-520: The next season the station began airing St. Louis Cardinals ' games. During the 1930s and 1940s, KMOX was one of several St. Louis stations broadcasting both the Cardinals and St. Louis Browns baseball games. KMOX lost broadcasting rights in 1948 when a new Cardinals radio network was formed by the team, but by the 1950s, it became the flagship station of that network (in part due to its clear channel status). KMOX's most famous sports broadcaster
10353-549: The number of stations increased to 732. To rectify the matter, Congress passed the Radio Act of 1927, which was signed into law by President Calvin Coolidge on February 23, 1927. The Act adopted a standard that radio stations had to be shown to be "in the public interest, convenience, or necessity". The FRC started reducing the number of stations, beginning with eliminating "portable" stations. Two technical issues limited
10472-403: The number of stations that could operate without interfering with each other. These issues were especially important at night, when a change in the ionosphere meant that radio signals traveled much greater distances. Most transmitters at this time were unable to precisely control their output frequencies, thus, signals from two stations operating on the same nominal frequency would combine to make
10591-411: 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,
10710-433: 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
10829-615: The post in 1993 when he was poached by KTRS . Bob Costas did play-by-play on KMOX for the Spirits of St. Louis of the American Basketball Association from 1974 until the ABA-NBA merger in June 1976. At times, the station's emphasis had shifted away from broadcasting St. Louis professional sports teams. In 2000, the St. Louis Blues hockey team moved to KTRS after having been on KMOX for all but three of
10948-441: 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
11067-612: The process of getting approval to build a 50,000-watt transmitter tower. When completed, it gave the now a signal that could be heard at night through much of the U.S. In the early days of radio, KMOX broadcasts had been picked up in Scotland , New Zealand, the Arctic Circle and South Africa. In 1933, KMOX covered the first post- Prohibition case of Budweiser beer leaving the Anheuser-Busch St. Louis brewery for
11186-650: 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
11305-420: The road (later adult contemporary ) music. In 1955, Robert Hyland Jr. became KMOX's general manager, a role he held for nearly forty years. It was Hyland who leveraged KMOX's relationship with the Cardinals, signing many lucrative advertising contracts with local businesses. Hyland made the decision in 1960 to eliminate the station's afternoon music programming, the last of the non-talk shows. That made KMOX
11424-799: 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
11543-475: The same market, but with different ownership from sharing the same callsign, it subsequently amended its call sign to KMOV. KMOX added an FM station on February 12, 1962. It broadcast at 103.3 MHz and mostly simulcast the AM station. By the late 1960s, KMOX-FM was separately programmed, airing an easy listening format, then later shifted to Top 40 as KHTR in 1982, and is currently classic hits KLOU , owned by iHeartMedia, Inc. In July 1968, CBS opened
11662-400: 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
11781-410: 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,
11900-742: The station from 2005 to 2008. Becky Domyan, who also oversees sister stations KEZK and KYKY is the station's current Market Manager & Sr. Vice President for Entercom. KMOX started broadcasting in HD Radio in May 2006. For many years, KMOX broadcast using C-QUAM 's AM Stereo technology, but stereo transmissions ended in the spring of 2000. On January 30, 2012, Jon Grayson's Overnight America , based at KMOX, and also airing on CBS stations WCCO in Minneapolis and KDKA in Pittsburgh , became
12019-568: The team's 33 seasons (1967–2000), but the games returned starting in the 2006–07 season . The St. Louis Blues moved to WXOS starting in the 2019–2020 season. In 2006, the Cardinals' broadcasts moved to KTRS after 52 seasons on KMOX (1954–2005) after the team purchased controlling interest in KTRS. On September 1, 2010, the Cardinals announced the return of broadcasts to KMOX, starting in the 2011 baseball season. KMOX aired University of Missouri Tigers Football and basketball games for many years, and
12138-411: 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
12257-401: 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
12376-496: 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
12495-548: 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
12614-404: 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
12733-434: Was Jack Buck , who was the station's year-round sports director during the years he was also calling baseball and football for the CBS radio and television networks. Another famous announcer was Harry Caray , who did play-by-play for Cardinals' baseball from 1945 through 1969. Dan Kelly was hired in 1968 to broadcast the new Blues hockey team and became the voice of hockey in the city until his death in 1989: his son John
12852-572: 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
12971-590: Was added because the starting date was Christmas Eve, or Xmas Eve. A local legend states the call letters mean Kirkwood, Missouri On Xmas. In 1927 the station gave prominent coverage to the Charles Lindbergh flight across the Atlantic in his plane The Spirit of St. Louis . That same year, KMOX became one of the first 16 stations in the CBS Radio Network . Following the establishment of
13090-474: 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
13209-477: Was considered of limited value for adult education. The deleted stations were mostly small ones with limited financial backing. One notable exception was a Chicago-area station, WMBB-WOK. This station was primarily owned by the American Bond and Mortgage Company, which unsuccessfully challenged its elimination in the federal courts. With the number of stations now somewhat reduced, the FRC's next major step
13328-411: Was deleted due to technical violations. According to the FRC, a total of 62 stations were eliminated as a result of General Order 32, with 81 surviving, although many of the latter were reduced in power or moved to less desirable frequencies. Educational stations fared particularly poorly. They were usually required to share frequencies with commercial stations and operate only during the daytime, which
13447-400: 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
13566-509: Was named general manager. He departed in 1998 to manage CBS station WBBM Radio in Chicago. KMOX picked up Costas Coast to Coast in 1994. Also, in July of that year Bob Costas began hosting a sports call-in show on the station. Karen Carroll was general manager from 1998 until 2003, when Tom Langmyer was promoted to the top position. Langmyer left in 2005 to become vice president/general manager of WGN Radio in Chicago. Dave Ervin managed
13685-603: Was sent to these stations: Dear Sir: Please note copy of attached Order No. 32 in which the commission has extended your present license for a period of 60 days. From an examination of your application for future license it does not find that public interest, convenience, or necessity would be served by granting it. The commission has fixed the date for hearing on this application on July 9, at 10 o'clock a.m. in its offices at Washington, D. C. At this hearing, unless you can make an affirmative showing that public interest, convenience, or necessity will be served by
13804-470: Was started in the early 1920s by a group of businessmen who formed a company known as "The Voice of St. Louis, Inc." The station's owners wanted KVSL, for "Voice of St. Louis". The owners also applied for KMO, with MO the abbreviation for Missouri, but those call letters had been in use by another station since 1922, KMO (now KKMO ) in Tacoma, Washington . KMOX signed on the air on December 24, 1925. The "X"
13923-473: 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
14042-560: Was the flagship of their radio network until the 1990s. Starting in 2011, the Tigers moved their basketball, football, and news & talk programs to 550 KTRS. The station continues to host sports programming such as "Sports Open Line". Matt Pauley is the main host. Notable current and past KMOX broadcasters include: ** = Audacy operates pursuant to a local marketing agreement with Martz Communications Group . AM broadcasting The earliest experimental AM transmissions began in
14161-406: 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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