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"AM Radio" redirects here. For the song by Everclear, see AM Radio (song). AM Radio is a rock song by the band Everclear. This song samples Jean Knight 's song " Mr

AM broadcasting is the process of radio broadcasting using amplitude modulation. This article is about radio broadcasting for other uses see Radio (disambiguation. Amplitude modulation ( AM) is a technique used in electronic communication most commonly for transmitting information via a Radio Carrier wave

Contents

History

Main articles: History of radio and Oldest radio station

AM was the dominant method of broadcasting during the first eighty years of the 20th century and remains widely used into the 21st. The pre-history and early history of radio is the history of Technology that produced radio instruments that use Radio waves Within the Timeline of The title of Oldest Radio Station is a controversial one but can be assumed from several in Europe (particularly of the UK and Germany) and in the

AM radio began with the first, experimental broadcast in 1906 by Reginald Fessenden, and was used for small-scale voice and music broadcasts up until World War I. Reginald Aubrey Fessenden ( October 6, 1866 &ndash July 22, 1932) born in East Bolton, Quebec, Canada, was World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All The great increase in the use of AM radio came the following decade. The first licensed commercial radio services began on AM in the 1920s. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. XWA of Montreal, Quebec (later CFCF) was the first commercial broadcaster in the world, with regular broadcasts commencing on May 20, 1920. Montreal, or Montréal in French ( pronounced in French, in English) is the largest city in the Canadian province of Quebec Quebec (kwɨˈbɛk The first licensed American radio station was started by Frank Conrad, KDKA in Pittsburgh, Pennsylvania. Frank Conrad (1874 &ndash 1941 was a Radio Broadcasting pioneer who worked as the Assistant Chief Engineer for the Westinghouse Electric Company in KDKA (1020 AM) is a Radio station in Pittsburgh Pennsylvania and is often said to be the oldest commercial radio station in the United States The Commonwealth of Pennsylvania ( often colloquially referred to as PA (its abbreviation by natives and Northeasterners is a state located in the Northeastern Radio programming boomed during the "Golden Age of Radio" (1920s–1950s). Radio programming is the content that is broadcast by Radio stations The original inventors of radio such as Nikola Tesla and Guglielmo Old-Time Radio (OTR and the Golden Age of Radio refer to a period of Radio programming lasting from the proliferation of radio broadcasting in the early 1920s until Dramas, comedy and all other forms of entertainment were produced, as well as broadcasts of news and music.

Operation

AM radio technology is simpler than FM radio and DAB. See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that Digital Audio Broadcasting ( DAB) also known as Eureka 147, is a Digital radio technology for Broadcasting Radio stations used in An AM receiver detects amplitude variations in the radio waves at a particular frequency. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. It then amplifies changes in the signal voltage to drive a loudspeaker or earphones. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical For the Marty Friedman album see Loudspeaker (album A loudspeaker, speaker, or speaker system is an electroacoustical Headphones (also known as earphones, earbuds, stereophones, headsets) are a pair of small Loudspeakers or less commonly a single The earliest crystal radio receivers used a crystal diode detector with no amplification. Dioden2jpg|thumb|right|150px|Figure 2 Various semiconductor diodes

In North American broadcasting practice, transmitter power input to the antenna for commercial AM stations ranges from about 250 watts to 50,000 watts. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. Experimental licenses were issued for up to 500,000 watts radiated power, for stations intended for wide-area communication during disasters, but no current commercial broadcaster in the US or Canada is authorized for such power levels. Other countries authorize higher power operation (for example the Mexican station XERF formerly operated at 250,000 watts). The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America. The call letters XERF-AM are assigned to a licensed border-blaster radio station that was located in Villa Acuña, Coahuila, (later renamed Ciudad Acuña Antenna design must consider the coverage desired and must direct the transmitted signal so as not to interfere with other stations operating on the same or adjacent frequencies.

Medium wave and short wave radio signals act differently during daytime and nighttime. During the day, AM signals travel by groundwave, diffracting around the curve of the earth over a distance up to a few hundred miles (or kilometers) from the signal transmitter. In Physics, surface wave can refer to a Mechanical wave that propagates along the interface between differing media usually two fluids with different densities However, after sunset, changes in the ionosphere cause AM signals to travel by skywave, enabling AM radio stations to be heard much farther from their point of origin than is normal during the day. The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation Skywave is the propagation of electromagnetic waves bent (refracted back to the Earth's surface by the Ionosphere. This phenomenon can be easily observed by scanning an AM radio dial at night. As a result, many broadcast stations are required as a condition of license to reduce their broadcasting power significantly (or use directional antennas) after sunset, or even to suspend broadcasting entirely during nighttime hours. (Such stations are commonly referred to as daytimers. The term is also used in the context of T1 A clear channel, in its general sense is a communications channel, such as a radio )

In the United States, some AM radio stations are granted clear channel status, meaning that they broadcast on frequencies with few other stations allocated, allowing an extended coverage area. The term is also used in the context of T1 A clear channel, in its general sense is a communications channel, such as a radio Nowadays relatively few stations enjoy clear channel status. Commercial broadcasters generally rely on the ground-wave coverage only as their target market for advertising.

The hobby of listening to long distance signals is known as DX or DX'ing, from an old telegraph abbreviation for "distance". DXing is the hobby of tuning in and identifying distant Radio or Television signals or making two way radio contact with distant stations in Amateur radio For the HTML tag see HTML element. An abbreviation (from Latin brevis "short" Several non-profit hobbyist clubs are devoted exclusively to DXing the AM broadcast band, including the National Radio Club and International Radio Club of America. A non-profit organization ( abbreviated "NPO" also "not-for-profit" is a legally constituted Organization whose objective is to support or engage A hobby is a spare-time Recreational pursuit Etymology A Hobby horse is a wooden or Wickerwork toy made to be MW DX, short for Mediumwave DXing, is the hobby of receiving the reception of distant Mediumwave (known as The National Radio Club (frequently abbreviated "NRC" is a Non-profit Hobbyist organization formed in 1933 via the amalgamation of several regional Similarly, people listening to short wave transmissions are SWLing. Shortwave listening (abbreviated as SWLing) is the Hobby of tuning for Shortwave Radio broadcasts located on shortwave frequencies

Frequency bands

AM radio is broadcast 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 the U.S., for example) subject to international agreements. The Radio Regulations is an intergovernmental treaty text of the International Telecommunication Union (ITU the Geneva based specialised agency of the The United States of America —commonly referred to as the

Frequencies between the broadcast bands are used for other forms of radio communication, and are not broadcast services intended for reception by the general public.

Limitations

Because of its susceptibility to atmospheric and electrical interference, AM broadcasting now attracts mainly talk radio and news programming, while music radio and public radio mostly shifted to FM broadcasting in the late 1960s and 1970s. Talk radio is a Radio format containing discussion about topical issues News is any new information or information on Current events which is presented by print, broadcast, Internet, or Word of mouth Music radio is a radio format in which Music is the main broadcast content Public broadcasting refers to radio television and other electronic media outlets that receive some or all of their funding from the public See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that Previously, in the UK during the 1980s, BBC Radio 4 (a largely speech channel) had an FM location, whereas BBC Radio 1, a music channel, was confined to AM broadcasts over much of the UK. Frequency response is typically 40 Hz–5 kHz with a 50 dB S/N ratio. The decibel ( dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity relative to Signal-to-noise ratio (often abbreviated SNR or S/N) is an Electrical engineering concept also used in other fields (such as scientific Measurements

The limitation on AM fidelity comes from current receiver design. Moreover, to fit more transmitters on the AM broadcast band, in the United States maximum transmitted audio bandwidth is limited to 10 kHz by an NRSC standard adopted by the FCC. The National Radio Systems Committee ( NRSC) is an Organization Sponsored by the Consumer Electronics Association (CEA and the National Association

AM radio signals can be severely disrupted in large urban centres by metal structures, tall buildings and sources of radio frequency interference (RFI) and electrical noise, such as electrical motors, fluorescent lights, or lightning. As a result, AM radio in many countries has lost its dominance as a music broadcasting service, and in many cities is now relegated to news, sports, religious and talk radio stations. Talk radio is a Radio format containing discussion about topical issues Some musical genres – particularly country, oldies, nostalgia and ethnic/world music – survive on AM, especially in areas where FM frequencies are in short supply or in thinly populated or mountainous areas where FM coverage is poor.

Other distribution methods

Stereo transmissions are possible (see AM stereo), and hybrid digital broadcast systems are now being used around the world. Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical AM Stereo is a term given to a number of mutually incompatible techniques for Broadcasting stereo audio in the AM band in a manner In the United States, iBiquity's proprietary HD Radio has been adopted and approved by the FCC for medium wave transmissions, while Digital Radio Mondiale is a more open effort often used on the shortwave bands, and can be used alongside many AM broadcasts. The United States of America —commonly referred to as the iBiquity Digital Corporation is a company formed by the Merger of USA Digital Radio and Lucent Digital Radio, with the goal of creating HD Radio is the name used by iBiquity for a system of digital transmission for audio broadcast stations Digital Radio Mondiale ( DRM) is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly Shortwave bands are frequency allocations for use within the High frequency radio spectrum Both of these standards are capable of broadcasting audio of significantly greater fidelity than that of standard AM, and a theoretical frequency response of 0-16 kHz, in addition to stereo sound and text data.

While FM radio can also be received by cable, AM radio generally cannot, although an AM station can be converted into an FM cable signal. Cable Radio or Cable FM is a concept similar to that of Cable television, bringing Radio signals into Homes and Businesses via In Canada, cable operators that offer FM cable services are required by the CRTC to distribute all locally available AM stations in this manner. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page CRTC may also stand for Cathode Ray Tube Controller. Canadian Radio-television and Telecommunications Commission ( CRTC, in French Conseil In Switzerland a system known as "wire broadcasting" transmits AM signals over telephone lines in the longwave band. The longwave Radio band is a range of frequencies used for AM broadcasting, which extends from 148

Microbroadcasting

Some microbroadcasters and pirate radio broadcasters, especially those in the United States under the FCC's Part 15 rules, broadcast on AM to achieve greater range than is possible on the FM band. Microbroadcasting is the process of broadcasting a message to a relatively small audience The term pirate radio usually refers to illegal or unregulated radio transmissions The United States of America —commonly referred to as the In the US, Part 15 is an often-quoted section of Federal Communications Commission (FCC rules and Regulations mainly regarding un Licensed See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that On mediumwave (AM), such radio stations are often found between 1610 kHz and 1710 kHz. Hobbyists also use low-power AM transmitters to provide local programming for antique radio equipment in areas where AM programming is not widely available or is of questionable quality; in such cases the transmitter, which is designed to cover only the immediate property and perhaps nearby areas, is hooked up to a computer or music player.


See also

External links

See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that Analog transmission is a method of conveying voice data image signal or video information using a continuous signal which varies in amplitude phase or some other property in proportion The extended MW broadcast band (sometimes known as the X-band is a Medium wave broadcast allocation (1629 kHz –1715 kHz Compatible Amplitude Modulation - Digital or CAM-D is a proposed hybrid Digital radio format for AM broadcasting, put forth by well-known The following is a listing of Radio stations in North and Central America: Canada Canada has approximately 2000 originating radio stations not including The title of Oldest Radio Station is a controversial one but can be assumed from several in Europe (particularly of the UK and Germany) and in the
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