Radio Broadcasting

Radio broadcasting is an audio (sound) broadcasting service, traditionally broadcast through the air as radio waves (a form of electromagnetic radiation) from a transmitter to an antenna and a thus to a receiving device. 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

The 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. 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.

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. 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.[1] The commercial designation came from the type of license—they didn't start airing advertisements until a few 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.[1][2]

When internet based radio became feasible in the mid '90s, the new medium required no licensing and the 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.)[3] and began broadcasting commercial free from Antarctica.

MIT developed the "Radio Locator" List of Radio Stations.[4]. 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 sunspots.

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
•amateur radio stations