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.
127-520: WWCL (1440 AM ) is a Spanish Christian music and teaching station. Licensed to Lehigh Acres, Florida , United States, the station serves the Fort Myers area. This article about a radio station in Florida is a stub . You can help Misplaced Pages by expanding it . AM broadcasting The earliest experimental AM transmissions began in the early 1900s. However, widespread AM broadcasting
254-466: A call sign on the air to legally identify the operator or station. In some countries, the call sign assigned to the station must always be used, whereas in other countries, the call sign of either the operator or the station may be used. In certain jurisdictions, an operator may also select a "vanity" call sign although these must also conform to the issuing government's allocation and structure used for Amateur Radio call signs. Some jurisdictions require
381-472: 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
508-846: 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
635-456: A US citizen may operate under reciprocal agreements in Canada, but not a non-US citizen holding a US license. Many people start their involvement in amateur radio on social media or by finding a local club. Clubs often provide information about licensing, local operating practices, and technical advice. Newcomers also often study independently by purchasing books or other materials, sometimes with
762-570: 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
889-441: A club or organization for a period of time before a higher class of license can be acquired. A reciprocal licensing agreement between two countries allows bearers of an amateur radio license in one country under certain conditions to legally operate an amateur radio station in the other country without having to obtain an amateur radio license from the country being visited, or the bearer of a valid license in one country can receive
1016-464: A club or organization generally requires that an individual with a current and valid amateur radio license who is in good standing with the telecommunications authority assumes responsibility for any operations conducted under the club license or club call sign. A few countries may issue special licenses to novices or beginners that do not assign the individual a call sign but instead require the newly licensed individual to operate from stations licensed to
1143-610: 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
1270-635: 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
1397-564: 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
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#17327917630381524-619: A fee to obtain such a vanity call sign; in others, such as the UK, a fee is not required and the vanity call sign may be selected when the license is applied for. The FCC in the U.S. discontinued its fee for vanity call sign applications in September 2015, but replaced it as $ 35 in 2022. Call sign structure as prescribed by the ITU consists of three parts which break down as follows, using the call sign ZS1NAT as an example: Many countries do not follow
1651-580: 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
1778-463: 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
1905-561: A given period of time. In addition to contests, a number of amateur radio operating award schemes exist, sometimes suffixed with "on the Air", such as Summits on the Air , Islands on the Air, Worked All States and Jamboree on the Air . Amateur radio operators may also act as citizen scientists for propagation research and atmospheric science . Radio transmission permits are closely controlled by nations' governments because radio waves propagate beyond national boundaries, and therefore radio
2032-516: 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
2159-474: 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
2286-487: 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)
2413-404: A national licensing process and may instead require prospective amateur radio operators to take the licensing examinations of a foreign country. In countries with the largest numbers of amateur radio licensees, such as Japan, the United States, Thailand, Canada, and most of the countries in Europe, there are frequent license examinations opportunities in major cities. Granting a separate license to
2540-506: 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
2667-432: A nuisance. The use of "ham" meaning "amateurish or unskilled" survives today sparsely in other disciplines (e.g. "ham actor"). The amateur radio community subsequently began to reclaim the word as a label of pride, and by the mid-20th century it had lost its pejorative meaning. Although not an acronym or initialism, it is often written as "HAM" in capital letters. The many facets of amateur radio attract practitioners with
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#17327917630382794-472: A number after to indicate the political region; prefix CY indicates geographic islands. Prefix VA1 or VE1 is Nova Scotia , VA2 / VE2 is Quebec , VA3 / VE3 is Ontario , VA4 / VE4 is Manitoba , VA5 / VE5 is Saskatchewan , VA6 / VE6 is Alberta , VA7 / VE7 is British Columbia , VE8 is the Northwest Territories , VE9 is New Brunswick , VY0
2921-399: 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
3048-409: A pool of at least 350. To pass, 26 of the 35 questions must be answered correctly. The Extra Class exam has 50 multiple choice questions (drawn randomly from a pool of at least 500), 37 of which must be answered correctly. The tests cover regulations, customs, and technical knowledge, such as FCC provisions, operating practices, advanced electronics theory, radio equipment design, and safety. Morse Code
3175-486: 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
3302-539: A purely personal aim and without pecuniary interest" (either direct monetary or other similar reward); and to differentiate it from commercial broadcasting , public safety (such as police and fire), or professional two-way radio services (such as maritime, aviation, taxis, etc.). The amateur radio service ( amateur service and amateur-satellite service ) is established by the International Telecommunication Union (ITU) through
3429-423: 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
3556-436: A separate license and a call sign in another country, both of which have a mutually-agreed reciprocal licensing approvals. Reciprocal licensing requirements vary from country to country. Some countries have bilateral or multilateral reciprocal operating agreements allowing hams to operate within their borders with a single set of requirements. Some countries lack reciprocal licensing systems. Others use international bodies such as
3683-452: 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
3810-427: 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
3937-551: A wide range of interests. Many amateurs begin with a fascination with radio communication and then combine other personal interests to make pursuit of the hobby rewarding. Some of the focal areas amateurs pursue include radio contesting , radio propagation study, public service communication , technical experimentation , and computer networking . Hobbyist radio enthusiasts employ a variety of transmission methods for interaction . The primary modes for vocal communications are frequency modulation (FM) and single sideband (SSB). FM
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4064-461: 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'
4191-717: A year in the national capital and can be inordinately bureaucratic (for example in India) or challenging because some amateurs must undergo difficult security approval (as in Iran ). Currently, only Yemen and North Korea do not issue amateur radio licenses to their citizens. Some developing countries, especially those in Africa, Asia, and Latin America , require the payment of annual license fees that can be prohibitively expensive for most of their citizens. A few small countries may not have
4318-411: Is Nunavut , VY1 is Yukon , VY2 is Prince Edward Island , VO1 is Newfoundland , and VO2 is Labrador . CY is for amateurs operating from Sable Island (CY0) or St. Paul Island (CY9). Special permission is required to access either of these: from Parks Canada for Sable and Coast Guard for St. Paul. The last two or three letters of the call signs are typically the operator's choice (upon completing
4445-406: 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
4572-604: Is in the Turks and Caicos Islands, VP6xxx is on Pitcairn Island, VP8xxx is in the Falklands, and VP9xxx is in Bermuda. Online callbooks or call sign databases can be browsed or searched to find out who holds a specific call sign. An example of an online callbook is QRZ.com . Non-exhaustive lists of famous people who hold or have held amateur radio call signs have also been compiled and published. Many jurisdictions (but not in
4699-502: 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
4826-471: Is no longer tested in the U.S. Once the exam is passed, the FCC issues an Amateur Radio license which is valid for ten years. Studying for the exam is made easier because the entire question pools for all license classes are posted in advance. The question pools are updated every four years by the National Conference of VECs. Prospective amateur radio operators are examined on understanding of
4953-466: Is of international concern. Both the requirements for and privileges granted to a licensee vary from country to country, but generally follow the international regulations and standards established by the International Telecommunication Union and World Radio Conferences . All countries that license citizens to use amateur radio require operators to display knowledge and understanding of key concepts, usually by passing an exam. The licenses grant hams
5080-522: Is recognized for its superior audio quality, whereas SSB is more efficient for long-range communication under limited bandwidth conditions. Radiotelegraphy using Morse code , also known as "CW" from " continuous wave ", is the wireless extension of landline (wired) telegraphy developed by Samuel Morse and dates to the earliest days of radio. Although computer-based (digital) modes and methods have largely replaced CW for commercial and military applications, many amateur radio operators still enjoy using
5207-419: Is similar to Voice over IP (VoIP), but augments two-way radio communications rather than telephone calls. EchoLink using VoIP technology has enabled amateurs to communicate through local Internet-connected repeaters and radio nodes, while IRLP has allowed the linking of repeaters to provide greater coverage area. Automatic link establishment (ALE) has enabled continuous amateur radio networks to operate on
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5334-645: 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
5461-692: Is the Wireless Institute of Australia , formed in 1910; other notable societies are the Radio Society of Great Britain , the American Radio Relay League , Radio Amateurs of Canada , Bangladesh NGOs Network for Radio and Communication , the New Zealand Association of Radio Transmitters and South African Radio League . ( See Category:Amateur radio organizations ) An amateur radio operator uses
5588-684: Is typically found in the 70 cm (420–450 MHz) wavelength range, though there is also limited use on 33 cm (902–928 MHz), 23 cm (1240–1300 MHz) and shorter. These requirements also effectively limit the signal range to between 20 and 60 miles (30–100 km). Linked repeater systems, however, can allow transmissions of VHF and higher frequencies across hundreds of miles. Repeaters are usually located on heights of land or on tall structures, and allow operators to communicate over hundreds of miles using hand-held or mobile transceivers . Repeaters can also be linked together by using other amateur radio bands , landline , or
5715-619: Is valid only in the country where it is issued or in another country that has a reciprocal licensing agreement with the issuing country. In some countries, an amateur radio license is necessary in order to purchase or possess amateur radio equipment. Amateur radio licensing in the United States exemplifies the way in which some countries award different levels of amateur radio licenses based on technical knowledge: three sequential levels of licensing exams (Technician Class, General Class, and Amateur Extra Class) are currently offered, which allow operators who pass them access to larger portions of
5842-578: 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
5969-625: 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
6096-493: 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
6223-724: The Internet . Amateur radio satellites can be accessed, some using a hand-held transceiver ( HT ), even, at times, using the factory "rubber duck" antenna. Hams also use the moon , the aurora borealis , and the ionized trails of meteors as reflectors of radio waves. Hams can also contact the International Space Station (ISS) because many astronauts are licensed as amateur radio operators. Amateur radio operators use their amateur radio station to make contacts with individual hams as well as participate in round-table discussion groups or "rag chew sessions" on
6350-548: The Internet . Amateur radio is officially represented and coordinated by the International Amateur Radio Union (IARU), which is organized in three regions and has as its members the national amateur radio societies which exist in most countries. According to an estimate made in 2011 by the American Radio Relay League (the American national amateur radio society), two million people throughout
6477-474: The Radio Regulations . National governments regulate technical and operational characteristics of transmissions and issue individual station licenses with a unique identifying call sign , which must be used in all transmissions. Amateur operators must hold an amateur radio license which is obtained by passing a government test demonstrating adequate technical radio knowledge and legal knowledge of
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#17327917630386604-431: 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
6731-482: The high frequency bands with global coverage. Other modes, such as FSK441 using software such as WSJT , are used for weak signal modes including meteor scatter and moonbounce communications. Fast scan amateur television has gained popularity as hobbyists adapt inexpensive consumer video electronics like camcorders and video cards in PCs . Because of the wide bandwidth and stable signals required, amateur television
6858-430: 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
6985-603: 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
7112-660: 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
7239-532: 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
7366-686: The Amateur Radio spectrum and more desirable (shorter) call signs. An exam, authorized by the Federal Communications Commission (FCC), is required for all levels of the Amateur Radio license. These exams are administered by Volunteer Examiners, accredited by the FCC-recognized Volunteer Examiner Coordinator (VEC) system. The Technician Class and General Class exams consist of 35 multiple-choice questions, drawn randomly from
7493-531: 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
7620-524: The CW mode—particularly on the shortwave bands and for experimental work, such as Earth–Moon–Earth communication , because of its inherent signal-to-noise ratio advantages. Morse, using internationally agreed message encodings such as the Q code , enables communication between amateurs who speak different languages. It is also popular with homebrewers and in particular with "QRP" or very-low-power enthusiasts, as CW-only transmitters are simpler to construct, and
7747-533: The ITU convention for the numeral. In the United Kingdom the original calls G0xxx, G2xxx, G3xxx, G4xxx, were Full (A) License holders along with the last M0xxx full call signs issued by the City & Guilds examination authority in December 2003. Additional Full Licenses were originally granted to (B) Licenses with G1xxx, G6xxx, G7xxx, G8xxx and 1991 onward with M1xxx call signs. The newer three-level Intermediate License holders are assigned 2E0xxx and 2E1xxx, and
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#17327917630387874-503: The Isle of Man, "GJ" & "MJ" are Jersey and "GU" & "MU" are Guernsey. Intermediate licence call signs are slightly different. They begin 2#0 and 2#1 where the # is replaced with the country letters as above. For example "2M0" and "2M1" are Scotland, "2W0" and "2W1" are Wales and so on. The exception however is for England. The letter "E" is used, but only in intermediate-level call signs. For example "2E0" & "2E1" are used whereas
8001-461: The Organization of American States to facilitate licensing reciprocity. When traveling abroad, visiting amateur operators must follow the rules of the country in which they wish to operate. Some countries have reciprocal international operating agreements allowing hams from other countries to operate within their borders with just their home country license. Other host countries require that
8128-581: The RF spectrum, usually allowing choice of an effective frequency for communications across a local, regional, or worldwide path. The shortwave bands, or HF , are suitable for worldwide communication, and the VHF and UHF bands normally provide local or regional communication, while the microwave bands have enough space, or bandwidth , for amateur television transmissions and high-speed computer networks . In most countries, an amateur radio license grants permission to
8255-411: 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
8382-460: The U.S., for example) subject to international agreements. Amateur radio Amateur radio , also known as ham radio , is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport , contesting , and emergency communications . The term "amateur" is used to specify "a duly authorized person interested in radioelectric practice with
8509-428: The UK & Europe) may issue specialty vehicle registration plates to licensed amateur radio operators. The fees for application and renewal are usually less than the standard rate for specialty plates. In most administrations, unlike other RF spectrum users, radio amateurs may build or modify transmitting equipment for their own use within the amateur spectrum without the need to obtain government certification of
8636-552: The United Kingdom and Australia, have begun requiring a practical assessment in addition to the written exams in order to obtain a beginner's license, which they call a Foundation License. In most countries, an operator will be assigned a call sign with their license. In some countries, a separate "station license" is required for any station used by an amateur radio operator. Amateur radio licenses may also be granted to organizations or clubs. In some countries, hams were allowed to operate only club stations. An amateur radio license
8763-694: 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
8890-763: The air. Some join in regularly scheduled on-air meetings with other amateur radio operators, called " nets " (as in "networks"), which are moderated by a station referred to as "Net Control". Nets can allow operators to learn procedures for emergencies, be an informal round table, or cover specific interests shared by a group. Amateur radio operators, using battery- or generator-powered equipment, often provide essential communications services when regular channels are unavailable due to natural disaster or other disruptive events . Many amateur radio operators participate in radio contests, during which an individual or team of operators typically seek to contact and exchange information with as many other amateur radio stations as possible in
9017-523: 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
9144-482: 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
9271-513: The basic Foundation License holders are granted call signs M3xxx, M6xxx or M7xxx. Instead of using numbers, in the UK the second letter after the initial 'G' or 'M' identifies the station's location; for example, a call sign G7OOE becomes GM7OOE and M0RDM becomes MM0RDM when that license holder is operating a station in Scotland. Prefix "GM" & "MM" are Scotland, "GW" & "MW" are Wales, "GI" & "MI" are Northern Ireland, "GD" & "MD" are
9398-446: The call signs beginning G or M for foundation and full licenses never use the "E". In the United States, for non-vanity licenses, the numeral indicates the geographical district the holder resided in when the license was first issued. Prior to 1978, US hams were required to obtain a new call sign if they moved out of their geographic district. In Canada, call signs start with VA, VE, VY, VO, and CY. Call signs starting with 'V' end with
9525-404: 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
9652-501: The classroom to teach English, map skills, geography, math, science, and computer skills. The term "ham" was first a pejorative term used in professional wired telegraphy during the 19th century, to mock operators with poor Morse code -sending skills (" ham-fisted "). This term continued to be used after the invention of radio and the proliferation of amateur experimentation with wireless telegraphy; among land- and sea-based professional radio operators, "ham" amateurs were considered
9779-403: 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
9906-475: 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
10033-437: 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
10160-434: 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
10287-567: 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
10414-569: 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
10541-764: The early 20th century. The First Annual Official Wireless Blue Book of the Wireless Association of America , produced in 1909, contains a list of amateur radio stations. This radio callbook lists wireless telegraph stations in Canada and the United States, including 89 amateur radio stations. As with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science , engineering , industry, and social services . Research by amateur operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency. Ham radio can also be used in
10668-408: The equipment. Licensed amateurs can also use any frequency in their bands (rather than being allocated fixed frequencies or channels) and can operate medium-to-high-powered equipment on a wide range of frequencies so long as they meet certain technical parameters including occupied bandwidth, power, and prevention of spurious emission . Radio amateurs have access to frequency allocations throughout
10795-648: 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,
10922-445: 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
11049-401: 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
11176-624: 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,
11303-417: 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
11430-423: The help of a mentor, teacher, or friend. In North America, established amateurs who help newcomers are often referred to as "Elmers", as coined by Rodney Newkirk, W9BRD, within the ham community. In addition, many countries have national amateur radio societies which encourage newcomers and work with government communications regulation authorities for the benefit of all radio amateurs. The oldest of these societies
11557-598: The host government's radio regulations. Radio amateurs are limited to a specific set of frequency bands, the amateur radio bands, allocated throughout the radio spectrum , but within these bands are allowed to transmit on any frequency using a variety of voice, text, image, and data communications modes. This enables communication across a city, region, country, continent, the world, or even into space. In many countries, amateur radio operators may also send, receive, or relay radio communications between computers or transceivers connected to secure virtual private networks on
11684-822: The human ear-brain signal processing system can pull weak CW signals out of the noise where voice signals would be totally inaudible. A similar "legacy" mode popular with home constructors is amplitude modulation (AM), pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology. Demonstrating a proficiency in Morse code was for many years a requirement to obtain an amateur license to transmit on frequencies below 30 MHz. Following changes in international regulations in 2003, countries are no longer required to demand proficiency. The United States Federal Communications Commission , for example, phased out this requirement for all license classes on 23 February 2007. Modern personal computers have encouraged
11811-554: 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
11938-570: The key concepts of electronics, radio equipment, antennas, radio propagation , RF safety, and the radio regulations of the government granting the license. These examinations are sets of questions typically posed in either a short answer or multiple-choice format. Examinations can be administered by bureaucrats , non-paid certified examiners, or previously licensed amateur radio operators. The ease with which an individual can acquire an amateur radio license varies from country to country. In some countries, examinations may be offered only once or twice
12065-411: 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
12192-419: 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,
12319-417: The license holder to own, modify, and operate equipment that is not certified by a governmental regulatory agency. This encourages amateur radio operators to experiment with home-constructed or modified equipment. The use of such equipment must still satisfy national and international standards on spurious emissions . Amateur radio operators are encouraged both by regulations and tradition of respectful use of
12446-585: The licensing test, the ham writes three most-preferred options). Two-letter call sign suffixes require a ham to have already been licensed for 5 years. Call signs in Canada can be requested with a fee. Also, for smaller geopolitical entities, the numeral may be part of the country identification. For example, VP2xxx is in the British West Indies, which is subdivided into VP2Exx Anguilla, VP2Mxx Montserrat, and VP2Vxx British Virgin Islands. VP5xxx
12573-399: 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
12700-432: 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
12827-448: 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
12954-537: 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
13081-405: 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
13208-428: 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
13335-411: 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,
13462-433: 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
13589-441: 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
13716-892: The privilege to operate in larger segments of the radio frequency spectrum, with a wider variety of communication techniques, and with higher power levels relative to unlicensed personal radio services (such as CB radio , FRS , and PMR446 ), which require type-approved equipment restricted in mode, range, and power. Amateur licensing is a routine civil administrative matter in many countries. Amateurs therein must pass an examination to demonstrate technical knowledge, operating competence, and awareness of legal and regulatory requirements, in order to avoid interfering with other amateurs and other radio services. A series of exams are often available, each progressively more challenging and granting more privileges: greater frequency availability, higher power output, permitted experimentation, and, in some countries, distinctive call signs. Some countries, such as
13843-650: 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
13970-799: 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
14097-400: 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
14224-410: 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,
14351-497: The spectrum to use as little power as possible to accomplish the communication. This is to minimise interference or EMC to any other device. Although allowable power levels are moderate by commercial standards, they are sufficient to enable global communication. Lower license classes usually have lower power limits; for example, the lowest license class in the UK (Foundation licence) has a limit of 10 W. Power limits vary from country to country and between license classes within
14478-411: 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
14605-401: 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
14732-496: 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
14859-442: The use of digital modes such as radioteletype (RTTY) which previously required cumbersome mechanical equipment. Hams led the development of packet radio in the 1970s, which has employed protocols such as AX.25 and TCP/IP . Specialized digital modes such as PSK31 allow real-time, low-power communications on the shortwave bands but have been losing favor in place of newer digital modes such as FT8 . Radio over IP , or RoIP,
14986-461: The visiting ham apply for a formal permit, or even a new host country-issued license, in advance. The reciprocal recognition of licenses frequently not only depends on the involved licensing authorities, but also on the nationality of the bearer. As an example, in the US, foreign licenses are recognized only if the bearer does not have US citizenship and holds no US license (which may differ in terms of operating privileges and restrictions). Conversely,
15113-548: 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
15240-645: The world are regularly involved with amateur radio. About 830,000 amateur radio stations are located in IARU Region 2 (the Americas) followed by IARU Region 3 (South and East Asia and the Pacific Ocean) with about 750,000 stations. A significantly smaller number, about 400,000, are located in IARU Region 1 (Europe, Middle East, CIS , Africa). The origins of amateur radio can be traced to the late 19th century, but amateur radio as practised today began in
15367-404: 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
15494-572: 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
15621-474: 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
15748-400: 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
15875-703: 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
16002-473: 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
16129-406: 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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