Radio station - AbsoluteAstronomy.com

Radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

broadcasting is a one-way wireless

Wireless

Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

transmission over radio waves

Radio waves

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...

intended to reach a wide audience

Audience

An audience is a group of people who participate in a show or encounter a work of art, literature , theatre, music or academics in any medium...

. Stations can be linked in radio network

Radio network

There are two types of radio networks currently in use around the world: the one-to-many broadcast type commonly used for public information and mass media entertainment; and the two-way type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery...

s to broadcast a common radio format

Radio format

A radio format or programming format not to be confused with broadcast programming describes the overall content broadcast on a radio station. Radio formats are frequently employed as a marketing tool, and constantly evolve...

, either in broadcast syndication or simulcast

Simulcast

Simulcast, shorthand for "simultaneous broadcast", refers to programs or events broadcast across more than one medium, or more than one service on the same medium, at the same time. For example, Absolute Radio is simulcast on both AM and on satellite radio, and the BBC's Prom concerts are often...

or both. Audio broadcasting also can be done via cable radio

Cable radio

Cable radio or cable FM is a concept similar to that of cable television, bringing radio signals into homes and businesses via coaxial cable. It is generally used as cable TV was in its early days when it was "community antenna television", to enhance the quality of terrestrial radio signals that...

, local wire television network

Television network

A television network is a telecommunications network for distribution of television program content, whereby a central operation provides programming to many television stations or pay TV providers. Until the mid-1980s, television programming in most countries of the world was dominated by a small...

s, satellite radio

Satellite radio

Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...

, and internet radio

Internet radio

Internet radio is an audio service transmitted via the Internet...

via streaming media

Streaming media

Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...

on the Internet

Internet

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

.

The signal types can be either analog audio or digital audio

Digital audio

Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion , digital-to-analog conversion , digital storage, processing and transmission components...

.

Amateur radio

Amateur radio

Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

(also, ham radio) is a form of radio communication that is the private use of designated radio bands, for purposes of private recreation, non-commercial

Non-commercial

Non-commercial refers to an activity or entity that does not in some sense involve commerce, at least relative to similar activities that do have a commercial objective or emphasis...

exchange of messages, experimentation, self-training, and emergency communication.

History

The earliest radio

Radio

Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

stations were simply radiotelegraphy systems and did not carry audio. The first claimed audio transmission that could be termed a broadcast occurred on Christmas Eve

Christmas Eve

Christmas Eve refers to the evening or entire day preceding Christmas Day, a widely celebrated festival commemorating the birth of Jesus of Nazareth that takes place on December 25...

in 1906, and was made by Reginald Fessenden

Reginald Fessenden

Reginald Aubrey Fessenden , a naturalized American citizen born in Canada, was an inventor who performed pioneering experiments in radio, including early—and possibly the first—radio transmissions of voice and music...

. Whether this broadcast actually took place is disputed. While many early experimenters attempted to create systems similar to radiotelephone

Radiotelephone

A radiotelephone is a communications system for transmission of speech over radio. Radiotelephone systems are not necessarily interconnected with the public "land line" telephone network. "Radiotelephone" is often used to describe the usage of radio spectrum where it is important to distinguish the...

devices where only two parties were meant to communicate, there were others who intended to transmit to larger audiences. Charles Herrold

Charles Herrold

Charles David 'Doc' Herrold, was an American radio broadcasting pioneer who in 1909 created the world's second radio station....

started broadcasting in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

in 1909 and was carrying audio by the next year. (Herrold's station eventually became KCBS

KCBS (AM)

KCBS is an all-news radio station in San Francisco, California, that is a key West Coast flagship radio station of the CBS Radio Network and Westwood One. Its transmitter is located in Novato, California. KCBS currently has studios on Battery Street, where it shares the location with co-owned KPIX...

).

For the next decade, radio tinkerers had to build their own radio receivers. In The Hague, the Netherlands, PCGG started broadcasting on November 6, 1919. In 1916, Frank Conrad

Frank Conrad

Frank Conrad was a radio broadcasting pioneer who worked as the Assistant Chief Engineer for the Westinghouse Electric Corporation in Pittsburgh, Pennsylvania,...

, an employee for the Westinghouse Electric Corporation

Westinghouse Electric (1886)

Westinghouse Electric was an American manufacturing company. It was founded in 1886 as Westinghouse Electric Company and later renamed Westinghouse Electric Corporation by George Westinghouse. The company purchased CBS in 1995 and became CBS Corporation in 1997...

, began broadcasting from his Wilkinsburg, Pennsylvania

Wilkinsburg, Pennsylvania

Wilkinsburg is a borough in Allegheny County, Pennsylvania, United States adjacent to the city of Pittsburgh. The population was 15,930 at the 2010 census, having lost more than 13,000 in the 70 years since 1940, when 29,853 people were enumerated...

garage with the call letters 8XK. Later, the station was moved to the top of the Westinghouse factory building in East Pittsburgh, Pennsylvania

East Pittsburgh, Pennsylvania

East Pittsburgh is a borough in Allegheny County, Pennsylvania, about southeast of the confluence of the Monongahela and the Allegheny rivers at Pittsburgh. The population in 1900 stood at 2,883, and in 1910, at 5,615. As of the 2010 census, the borough population was 1,822, having fallen from...

. Westinghouse relaunched the station as KDKA

KDKA (AM)

KDKA is a radio station licensed to Pittsburgh, Pennsylvania, USA. Created by the Westinghouse Electric Corporation on November 2, 1920, it is one of the world's first modern radio stations , a distinction that has also been challenged by other stations, although it has claimed to be the first in...

on November 2, 1920, claiming to be "the world's first commercially licensed radio station". The commercial broadcasting

Commercial broadcasting

Commercial broadcasting is the broadcasting of television programs and radio programming by privately owned corporate media, as opposed to state sponsorship...

designation came from the type of broadcast license

Broadcast license

A broadcast license or broadcast license is a specific type of spectrum license that grants the licensee the privilege to use a portion of the radio frequency spectrum in a given geographical area for broadcasting purposes. The licenses are generally straddled with additional restrictions that...

; advertisement

Advertising

Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...

s did not air until years later. The first licensed broadcast in the United States came from KDKA itself: the results of the Harding/Cox Presidential Election. The Montreal

Montreal

Montreal is a city in Canada. It is the largest city in the province of Quebec, the second-largest city in Canada and the seventh largest in North America...

station that became CFCF began broadcast programming on May 20, 1920, and the Detroit station that became WWJ

WWJ (AM)

WWJ is Detroit, Michigan's only 24-hour all-news radio station. Broadcasting at 950 kHz, the station is owned and operated by CBS Corporation subsidiary CBS Radio. The station first went on the air on August 20, 1920 with the call sign 8MK...

began program broadcasts beginning on August 20, 1920, although neither held a license at the time.

Radio Argentina began regularly scheduled transmissions from the Teatro Coliseo in Buenos Aires

Buenos Aires

Buenos Aires is the capital and largest city of Argentina, and the second-largest metropolitan area in South America, after São Paulo. It is located on the western shore of the estuary of the Río de la Plata, on the southeastern coast of the South American continent...

on August 27, 1920, making its own priority claim. The station got its license on November 19, 1923. The delay was due to the lack of official Argentine licensing procedures before that date. This station continued regular broadcasting of entertainment and cultural fare for several decades.

Radio in education soon followed and colleges across the U.S. began adding radio broadcasting courses to their curricula. Curry College in Milton, Massachusetts introduced one of the first broadcasting majors in 1932 when the college teamed up with WLOE in Boston to have students broadcast programs.

Types

Broadcasting by radio takes several forms. These include AM

AM broadcasting

AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...

and FM

FM broadcasting

FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...

stations. There are several subtypes, namely commercial broadcasting

Commercial broadcasting

Commercial broadcasting is the broadcasting of television programs and radio programming by privately owned corporate media, as opposed to state sponsorship...

, non-commercial educational

Non-commercial educational

The term non-commercial educational applies to a radio station or TV station that does not accept on air advertisements , as defined in the United States by the Federal Communications Commission . NCE stations do not pay broadcast license fees for their non-profit uses of the radio spectrum...

(NCE) public broadcasting

Public broadcasting

Public broadcasting includes radio, television and other electronic media outlets whose primary mission is public service. Public broadcasters receive funding from diverse sources including license fees, individual contributions, public financing and commercial financing.Public broadcasting may be...

and non-profit varieties as well as community radio

Community radio

Community radio is a type of radio service, that offers a third model of radio broadcasting beyond commercial broadcasting and public broadcasting. Community stations can serve geographic communities and communities of interest...

, student-run campus radio

Campus radio

Campus radio is a type of radio station that is run by the students of a college, university or other educational institution. Programming may be exclusively by students, or may include programmers from the wider community in which the radio station is based...

stations and hospital radio

Hospital radio

Hospital radio is a form of audio broadcasting produced specifically for the in-patients of hospitals. It is primarily found in the United Kingdom.-History:...

stations can be found throughout the world.

Many stations broadcast on shortwave

Shortwave

Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

bands using AM technology that can be received over thousands of miles (especially at night). For example, the BBC

BBC World Service

The BBC World Service is the world's largest international broadcaster, broadcasting in 27 languages to many parts of the world via analogue and digital shortwave, internet streaming and podcasting, satellite, FM and MW relays...

, VOA

Voice of America

Voice of America is the official external broadcast institution of the United States federal government. It is one of five civilian U.S. international broadcasters working under the umbrella of the Broadcasting Board of Governors . VOA provides a wide range of programming for broadcast on radio...

, VOR

Voice of Russia

Voice of Russia is the Russian government's international radio broadcasting service owned by the All-Russia State Television and Radio Company. Its predecessor Radio Moscow was the official international broadcasting station of the Union of Soviet Socialist Republics.-Early years:Radio Moscow...

, and Deutsche Welle

Deutsche Welle

Deutsche Welle or DW, is Germany's international broadcaster. The service is aimed at the overseas market. It broadcasts news and information on shortwave, Internet and satellite radio on 98.7 DZFE in 30 languages . It has a satellite television service , that is available in four languages, and...

have transmitted via shortwave to Africa and Asia. These broadcasts are very sensitive to atmospheric conditions and solar activity.

Arbitron

Arbitron

Arbitron is a consumer research company in the United States that collects listener data on radio audiences. It was founded as American Research Bureau by Jim Seiler in 1949 and became national by merging with L.A. based Coffin, Cooper and Clay in the early 1950s...

, the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

-based company that reports on radio audiences, defines a "radio station" as a government-licensed AM or FM station; an HD Radio (primary or multicast) station; an internet stream of an existing government-licensed station; one of the satellite radio channels from XM Satellite Radio

XM Satellite Radio

XM Satellite Radio is one of two satellite radio services in the United States and Canada, operated by Sirius XM Radio. It provides pay-for-service radio, analogous to cable television. Its service includes 73 different music channels, 39 news, sports, talk and entertainment channels, 21 regional...

or Sirius Satellite Radio

Sirius Satellite Radio

Sirius Satellite Radio is a satellite radio service operating in North America, owned by Sirius XM Radio.Headquartered in New York City, with smaller studios in Los Angeles and Memphis, Sirius was officially launched on July 1, 2002 and currently provides 69 streams of music and 65 streams of...

; or, potentially, a station that is not government licensed.

Shortwave

See Shortwave

Shortwave

for the differences between shortwave, medium wave and long wave spectra. Used largely for national broadcasters, international propaganda, or religious broadcasting

Religious broadcasting

Religious broadcasting refers to broadcasting by religious organizations, usually with a religious message. Many religious organizations have long recorded content such as sermons and lectures, and have moved into distributing content on their Internet websites.While this article emphasises...

organizations.

AM

AM stations were the earliest broadcasting stations to be developed. AM refers to amplitude modulation

Amplitude modulation

Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...

, a mode of broadcasting radio waves by varying the amplitude of the carrier signal in response to the amplitude of the signal to be transmitted.

The medium-wave band is used worldwide for AM broadcasting. Europe also uses the long wave band. In response to the growing popularity of FM radio stereo radio stations in the late 1980s and early 1990s, some North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n stations began broadcasting in AM stereo

AM stereo

AM stereo is a term given to a series of mutually incompatible techniques for wireless radio broadcasting stereo audio in the AM band in a manner that is compatible with standard AM receivers...

, though this never gained popularity, and very few receivers were ever sold.

One of the advantages of AM is that its signal can be detected (turned into sound) with simple equipment. If a signal is strong enough, not even a power source is needed; building an unpowered crystal radio receiver is a common childhood project.

AM broadcasts occur on North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n airwaves in the medium wave frequency range of 530 to 1700 kHz

Hertz

The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

(known as the "standard broadcast band"). The band was expanded in the 1990s by adding nine channels

Channel (communications)

In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...

from 1620 to 1700 kHz. Channels are spaced every 10 kHz in the Americas

Americas

The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

, and generally every 9 kHz everywhere else.

The signal is subject to interference from electrical storms (lightning

Lightning

Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

) and other electromagnetic interference

Electromagnetic interference

Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...

(EMI).

AM transmissions cannot be ionospherically propagated

Radio propagation

Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

during the day due to strong absorption in the D-layer of the ionosphere. In a crowded channel environment this means that the power of regional channels which share a frequency must be reduced at night or directionally beamed in order to avoid interference, which reduces the potential nighttime audience. Some stations have frequencies unshared with other stations in North America; these are called clear-channel stations. Many of them can be heard across much of the country at night. This is not to be confused with Clear Channel Communications

Clear Channel Communications

Clear Channel Communications, Inc. is an American media conglomerate company headquartered in San Antonio, Texas. It was founded in 1972 by Lowry Mays and Red McCombs, and was taken private by Bain Capital LLC and Thomas H. Lee Partners LP in a leveraged buyout in 2008...

, merely a brand name, which currently owns many U.S. radio stations on both the AM and FM bands. During the night, this absorption largely disappears and permits signals to travel to much more distant locations via ionospheric reflections. However, fading of the signal can be severe at night.

AM radio transmitters can transmit audio frequencies up to 15 kHz (now limited to 10 kHz in the US due to FCC rules designed to reduce interference), but most receivers are only capable of reproducing frequencies up to 5 kHz or less. At the time that AM broadcasting began in the 1920s, this provided adequate fidelity for existing microphones, 78 rpm recordings, and loudspeakers. The fidelity of sound equipment subsequently improved considerably, but the receivers did not. Reducing the bandwidth of the receivers reduces the cost of manufacturing and makes them less prone to interference. AM stations are never assigned adjacent channels in the same service area. This prevents the sideband power generated by two stations from interfering with each other. Bob Carver

Bob Carver

Robert W. Carver is an American designer of audio equipment based in the Pacific Northwest.Educated as a physicist and engineer, he found an interest in audio equipment at a very young age. He applied his talent to produce numerous innovative high fidelity designs since the 1970s...

created an AM stereo

AM stereo

AM stereo is a term given to a series of mutually incompatible techniques for wireless radio broadcasting stereo audio in the AM band in a manner that is compatible with standard AM receivers...

tuner employing notch filtering that demonstrated that an AM broadcast can meet or exceed the 15 kHz baseband bandwidth alloted to FM

FM broadcasting

stations without objectionable interference. After several years, the tuner was discontinued. Bob Carver had left the company and the Carver Corporation later cut the number of models produced before discontinuing production completely.

FM

FM refers to frequency modulation

Frequency modulation

In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...

, and occurs on VHF airwaves in the frequency range of 88 to 108 MHz everywhere (except Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

and Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

). Japan uses the 76 to 90 MHz band. Russia has two bands widely used by the Soviet Union, 65.9 to 74 MHz and 87.5 to 108 MHz worldwide standard. FM stations are much more popular since higher sound fidelity and stereo

Stereophonic sound

The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...

broadcasting became common in this format.

FM radio was invented by Edwin H. Armstrong in the 1930s for the specific purpose of overcoming the interference problem of AM radio, to which it is relatively immune. At the same time, greater fidelity was made possible by spacing stations further apart. Instead of 10 kHz apart, as on the AM band in the US, FM channels are 200 kHz (0.2 MHz) apart. In other countries greater spacing is sometimes mandatory, such as in New Zealand, which uses 700 kHz spacing (previously 800 kHz). The improved fidelity made available was far in advance of the audio equipment of the 1940s, but wide interchannel spacing was chosen to take advantage of the noise-suppressing feature of wideband FM.

Bandwidth of 200 kHz is not needed to accommodate an audio signal — 20 kHz to 30 kHz is all that is necessary for a narrowband FM signal. The 200 kHz bandwidth allowed room for ±75 kHz signal deviation from the assigned frequency, plus guard bands to reduce or eliminate adjacent channel interference. The larger bandwidth allows for broadcasting a 15 kHz bandwidth audio signal plus a 38 kHz stereo "subcarrier"—a piggyback signal that rides on the main signal. Additional unused capacity is used by some broadcasters to transmit utility functions such as background music

Music

Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...

for public areas, GPS

Global Positioning System

The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

auxiliary signals, or financial market data.

The AM radio problem of interference at night was addressed in a different way. At the time FM was set up, the available frequencies were far higher in the spectrum than those used for AM radio - by a factor of approximately 100. Using these frequencies meant that even at far higher power, the range of a given FM signal was much shorter; thus its market was more local than for AM radio. The reception range at night is the same as in the daytime.

The original FM radio service in the U.S. was the Yankee Network, located in New England

New England

New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...

. Regular FM broadcasting began in 1939, but did not pose a significant threat to the AM broadcasting industry. It required purchase of a special receiver. The frequencies used, 42 to 50 MHz, were not those used today. The change to the current frequencies, 88 to 108 MHz, began after the end of World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, and was to some extent imposed by AM broadcasters as an attempt to cripple what was by now realized to be a potentially serious threat.

FM radio on the new band had to begin from the ground floor. As a commercial venture it remained a little-used audio enthusiasts' medium until the 1960s. The more prosperous AM stations, or their owners, acquired FM licenses and often broadcast the same programming on the FM station as on the AM station ("simulcasting"). The FCC limited this practice in the 1970s. By the 1980s, since almost all new radios included both AM and FM tuners, FM became the dominant medium, especially in cities. Because of its greater range, AM remained more common in rural environments.

Pirate radio

Pirate radio is radio broadcasting not sanctioned by the regulations of the originating country. Pirate radio may be a commercial enterprise supported by advertising targeted to listeners in the reception area, or may be privately run for entertainment, or political reasons, sometimes on a very small scale covering only a few city blocks.

Terrestrial digital radio

Digital radio

Digital radio has several meanings:1. Today the most common meaning is digital radio broadcasting technologies, such as the digital audio broadcasting system, also known as Eureka 147. In these systems, the analog audio signal is digitized into zeros and ones, compressed using formats such as...

broadcasting has emerged, first in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

(the UK

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

in 1995 and Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

in 1999), and later in the United States, France, the Netherlands, South Africa and many other countries worldwide. The most simple system is named DAB Digital Radio, for Digital Audio Broadcasting

Digital audio broadcasting

Digital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....

, and uses the public domain

Public domain

Works are in the public domain if the intellectual property rights have expired, if the intellectual property rights are forfeited, or if they are not covered by intellectual property rights at all...

EUREKA 147

Digital audio broadcasting

(Band III) system. DAB is used mainly in the UK and South Africa. Germany and Holland use the DAB and DAB+ systems, and France use the L-Band system of DAB Digital Radio.

In the United States digital radio isn't used in the same way as Europe and South Africa. Instead, the IBOC system is named HD Radio

HD Radio

HD Radio, which originally stood for "Hybrid Digital", is the trademark for iBiquity's in-band on-channel digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals...

and owned by a consortium

Consortium

A consortium is an association of two or more individuals, companies, organizations or governments with the objective of participating in a common activity or pooling their resources for achieving a common goal....

of private companies that is called iBiquity

IBiquity

iBiquity Digital Corporation is a company formed by the merger of USA Digital Radio and Lucent Digital Radio, with the goal of creating an in-band on-channel digital radio system for the United States and around the world...

. An international non-profit consortium Digital Radio Mondiale

Digital Radio Mondiale

Digital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly shortwave...

(DRM), has introduced the public domain

Public domain

DRM system.

Satellite

Satellite radio

Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...

broadcasters are slowly emerging, but the enormous entry costs of space-based satellite transmitters, and restrictions on available radio spectrum

Radio spectrum

Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz ....

licenses has restricted growth of this market. In the USA and Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, just two services, XM Satellite Radio

XM Satellite Radio

and Sirius Satellite Radio

Sirius Satellite Radio

exist. Both XM and Sirius are owned by Sirius XM Radio, which was formed by the merger of XM and Sirius on July 29, 2008

2008 in radio

Several events occurred in radio in 2008.- Events :* January 2: WWFT finished Christmas music stunting, rolling out the red carpet for Adult contemporary music branded as "Warm."...

, whereas in Canada

Canada

, XM Radio Canada

XM Radio Canada

XM Radio Canada was the operating name of Canadian Satellite Radio Holdings Inc. , a Canadian communications and media company, which was incorporated in 2002 to broadcast satellite radio in Canada...

and Sirius Canada

Sirius Canada

Sirius Canada is a Canadian company, a partnership between Slaight Communications, the Canadian Broadcasting Corporation and Sirius Satellite Radio, which was one of three services licensed by the CRTC on June 16, 2005 to introduce satellite radio service to Canada.On November 24, 2010, following...

remain separate companies.

Program formats

Radio program formats differ by country, regulation and markets. For instance, the U.S. Federal Communications Commission

Federal Communications Commission

The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

designates the 88–92 megahertz band in the U.S. for non-profit or educational programming, with advertising prohibited.

In addition, formats change in popularity as time passes and technology improves. Early radio equipment only allowed program material to be broadcast in real time, known as live broadcasting. As technology for sound recording improved, an increasing proportion of broadcast programming used pre-recorded material. A current trend is the automation

Automation

Automation is the use of control systems and information technologies to reduce the need for human work in the production of goods and services. In the scope of industrialization, automation is a step beyond mechanization...

of radio stations. Some stations now operate without direct human intervention by using entirely pre-recorded material sequenced by computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

control.

External links

Patents

, Georg Graf von Arco, "Radiotelegraphic station" (December 1913)
, Richard Pfund, "Station for the transmission and reception of electromagnetic wave energy". (November 1914)
, Gustav Reuthe, "Antenna for radiotelegraph station" (February 1917)

General

Federal Communications Commission website, fcc.gov
DXing.info - Information about radio stations worldwide
Radio-Locator.com- Links to 10,000 radio stations worldwide.
BBC reception advice
DXradio.50webs.com "The SWDXER" - with general SWL information and radio antenna tips.
RadioStationZone.com - 10.000+ radio stations worldwide with ratings, comments and listen live links
RadioBeta.com, search for stations around the globe
Online-Radio-Stations.org - The Web Radio Tuner has a comprehensive list of over 50.000 radio stations
RadioStations.com has a directory of radio stations and real-time music listings
ZoZanga.com List of radio stations and real-time music listings
MyTravelTunes.com Search for radio stations throughout the U.S.
UnwantedEmissions.com - A general reference to radio spectrum allocations.
Radio stanice - Search for radio stations throughout the Europe
NEC Lab - A tool to design and test antennas for Radio broadcasting.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

History

Types

Shortwave

AM

FM

Pirate radio

Terrestrial digital radio

Satellite

Program formats

See also

Further reading

External links