Radio broadcasting is an audio (sound) broadcasting service, broadcast through the air as radio waves (a form of electromagnetic radiation) from a transmitter to a receiving antenna. Stations can be linked in radio networks to broadcast common programming, either in syndication or simulcast or both. Audio broadcasting also can be done via cable FM, local wire networks, satellite and the Internet.
History
Main article: History of radioThe earliest radio 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 in 1906, and was made by Reginald Fessenden. Whether this broadcast actually took place is disputed. While many early experimenters attempted to create systems similar to radiotelephone devices where only two parties were meant to communicate, there were others who intended to transmit to larger audiences. Charles Herrold started broadcasting in California in 1909 and was carrying audio by the next year. (Herrold's station eventually became KCBS.)
For the next decade, radio tinkerers had to build their own radio receivers. Dr. Frank Conrad began broadcasting from his Wilkinsburg, Pennsylvania garage with the call letters KDKA. KDKA's first commercial broadcast was made from Saxonburg, Butler County, PA on November 2, 1920. Later, the equipment was moved to the top of an office building in Pittsburgh, Pennsylvania and purchased by Westinghouse. KDKA of Pittsburgh, under Westinghouse's ownership, started broadcasting as the first licensed "commercial" radio station on November 2 , 1920 . In The Hague, the Netherlands, PCGG started broadcasting almost a year earlier, on November 6 , 1919 . The commercial designation came from the type of license; advertisements did not air until years later. The first broadcast was the results of the U.S. presidential election, 1920. The Montreal station that became CFCF began program broadcasts on May 20 , 1920 , and the Detroit station that became WWJ 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 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.
Internet radio
When Internet-based radio became feasible in the mid-1990s, the new medium required no licensing and stations could broadcast from anywhere in the world without the need for over the air transmitters. This greatly reduced the overhead for establishing a station, and in 1996, George Maat started 'A' Net Station (A.N.E.T.) under the now defunct domain Advice-Net.com, and began broadcasting commercial-free from Antarctica.
MIT developed the "Radio Locator" List of Radio Stations. After stations started streaming audio on the Internet, Radio-Locator added this to their search engine so anyone could locate a station's website and listen to a station offering a worldwide stream. This list also tracks "terrestrial" radio stations who may not have live audio on the net, or even a website, but are able to find station information by various other search queries.
Types
The best known type of radiostation are the ones that broadcast via radiowaves. These include foremost AM and FM stations. There are several subtypes, namely commercial, public and nonprofit varieties as well as student-run campus radio stations and hospital radio stations can be found throughout the developed world.
Although now being eclipsed by internet-distributed radio, there are many stations that broadcast on shortwave bands using AM technology that can be received over thousands of miles (especially at night). For example, the BBC has a full schedule transmitted via shortwave. These broadcasts are very sensitive to atmospheric conditions and solar activity.
Also, many other non-broadcast types of radio stations exist. These include base stations for police, fire and ambulance networks, military base stations, dispatch base stations for taxis, trucks, and couriers, emergency broadcast systems, and amateur radio stations.
Arbitron, the United States based company which reports on radio audiences defines a "radio station" as one of: government-licensed AM or FM station an HD Radio (primary or multicast) station, an internet stream of an existing government-licensed station or one of the satellite radio channels from XM Satellite Radio or Sirius Satellite Radio.
Over radiowaves
Shortwave
See Shortwave for the differences between shortwave, medium wave and long wave spectra. Used largely for international broadcasts by organs of state propaganda, religious organizations, militaries and others.
AM
AM stations were the earliest broadcasting stations to be developed. AM refers to amplitude modulation, 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.
Many countries outside of the U.S. use a similar frequency band for AM transmissions. 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 American stations began broadcasting in AM stereo, though this never gained popularity, and very few receivers were ever sold.
Advantages
One of the advantages of AM is that its unsophisticated 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 was a common childhood project in the early years of radio. Another advantage to AM is that it uses a narrower bandwidth than FM.
AM broadcasts occur on North American airwaves in the medium wave frequency range of 530 to 1700 kHz (known as the "standard broadcast band"). The band was expanded in the 1990s by adding nine channels from 1620 to 1700 kHz. Channels are spaced every 10 kHz in the Americas, and generally every 9 kHz everywhere else.
Disadvantages
The signal is subject to interference from electrical storms (lightning) and other EMI.
AM transmissions cannot be ionospherically propagated 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, merely a brand name, which currently owns many U.S. radio stations.) 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 created an AM stereo tuner employing notch filtering that demonstrated that an AM broadcast can meet or exceed the 15 kHz baseband bandwidth allocted to FM 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. AM stereo broadcasts declined with the advent of HD Radio.
FM
FM refers to frequency modulation, and occurs on VHF airwaves in the frequency range
Free Live Radio | Online radio stations | Listen Free Internet Radio
Listen 24 Hour Live Online Radio with covering the thousands of free live internet Radio Stations worldwide at koffii.com ... Argentina; Australia; Austria; Bahamas; Barbados; Belgium ...
The First Solar Radio Station in Argentina : EcoWorldly
The First Solar Radio Station in Argentina ... This is the opening message of the radio station Paj ... We’ve done couple of 1-2weeks live broadcast in ...
Live radio stations from around the world, broadcasting right NOW to ...
Live Radio on the Internet - The best and most accurate live radio site with links to THOUSANDS of radio stations from 100 countries ... Argentina Armenia Aruba ...
Free Radio Stations, Free Internet Radio, Online Music, Live Web Radio
Offers free Internet radio stations including live web radio and online music stations. ... Argentina (3)
LIVE Argentina Radio Stations broadcasting on internet
Live tv and radio on internet, live radio ... Live web-television stations and radio stations broadcasting on the Internet
Radio Mitre (Buenos Aires/Argentina) - Radio and TV stations in ...
Radio Mitre: comprehensive - listen and get familiarized how people speak the Spanish in Buenos Aires/Argentina.
Argentina Radio Stations Live Internet Radio Feeds - Instantly ...
Argentina Radio Stations Online - RadioTower makes it easy with details, descriptions, ratings and 1-click instant access to Argentina LIVE Radio feeds
Argentina radio, live Argentinian radio stations streaming
Argentina television, live Argentinian radio stations streaming
FM 97.1 Radio Galactica - Tandil - Argentina - Internet Radio ...
Argentina City: Tandil Language: Spanish Speed: 17 Sound: Stereo Radio/TV: Radio Live/On Demand : Live Station type: General Station Player: Windows Media
Argentina Internet Radio Stations - Argentina Radio Online - iheard
Find Argentina radio stations listed online at iheard.com. At iheard.com you'll find thousands of ... House Music Radio Plays Uplifting House Music All Week Long Featuring Live And ...