History of radio
The pre- and early history of radio is the history of its technology. See also the History of Science and Technology. Later, the history is dominated by programming and contents, which is closer to general History.
Radio's prehistory (19th century)
In St. Louis, Missouri, Nikola Tesla made the first public demonstration of radio communication in 1893. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of radio communication. The apparatus that he used contained all the elements that were incorporated into radio systems before the development of the vacuum tube.
In 1895, Guglielmo Marconi sent a telegraph message without wires, but he didn't send voice over the airwaves; Reginald Fessenden, in 1900, accomplished that. On Christmas Eve, 1906, using his heterodyne principle, Reginald Fessenden transmitted the first radio broadcast in history from Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing the song O Holy Night on the violin and reading a passage from the Bible.
The first benefit seen to radio telegraphy was the ability to establish communication between coast radio stations and ships at sea. A company called British Marconi was established to make use of Marconi's and others' patents. This company along with its subsidiary American Marconi , had a stranglehold on ship to shore communication. It operated much the way American Telephone and Telegraph operated until 1983, owning all of its own equipment and refusing to communicate with non-Marconi equipped ships. Many inventions improved the quality of radio, and amateurs experimented with uses of radio, thus the first seeds of broadcasting were planted.
- Quickly becomes popular on ships after the Titanic.
A typical high-power spark gap was a rotating commutator with six to twelve contacts per wheel, 9 inches to a foot wide, driven by about 2000 volts DC. As the gaps made and broke contact, the radio wave was audible as a tone in a crystal set. The telegraph key often directly made and broke the 2000 volt supply. One side of the spark gap was directly connected to the antenna. Receivers with thermionic valves became commonplace before spark-gap transmitters were replaced by continuous wave transmitters.
Audio Broadcasting (1915--)
- Invention of the triode amplifier, generator, and detector enables audio radio
Radio broadcasting is born
Westinghouse in Pittsburgh, Pennsylvania and the Scripps ' Detroit News in Detroit, Michigan were the first US broadcasters in the early 1920s. Broadcasting was not yet commercially supported; the stations owned by the manufacturers and department stores were established to sell radios and those owned by newspapers to sell newspapers and express the opinions of the owners. Westinghouse was brought into the patent allies group, General Electric, American Telephone and Telegraph, and Radio Corporation of America, and became a part owner of RCA. All radios made by GE and Westinghouse were sold under the RCA label 60% GE and 40% Westinghouse. ATT's Western Electric would build radio transmitters. The patent allies attempted to set up a monopoly, but they failed due to successful competition. Much to the dismay of the patent allies, several of the contracts for inventor's patents held clauses protecting "amateurs" and allowing them to use the patents. Whether the competing manufacturers were really amateurs was ignored by these competitors.
- Commercial (United States) or governmental (Europe) station networks
- Federal Radio Commission
- Federal Communications Commission
- Birth of the soap opera
- Race towards shorter waves and FM
FM radio, and later stereo FM radio, were both developed in the United States.
W1XOJ was the first experimental FM radio station, granted a construction permit by the FCC in 1937.
FM radio had been assigned the 42 to 50 MHz band of the spectrum in 1940. The Federal Communications Commission in late 1943 asked the radio manufacturers to establish the Radio Technical Planning Board , which would advise the Federal Communications Commission on allocation and other technical matters. The Radio Technical Planning Board was divided into panels on various subjects which would make recommendations to the whole board, which the board might support. The Radio Technical Planning Board FM panel recommended that more frequencies should be given to FM in the 50 MHz area where FM was already assigned and operating. Unfortunately for FM and the nearly 400,000 FM receiver owners the Radio Technical Planning Board as a whole did not agree with the panel. The reason the board made this decision was that it had been given flawed evidence by a former Federal Communications Commission engineer named Kenneth Norton . He believed that sunspots, which appear every eleven years, would cause severe disruption to the FM signal. Norton never explained why television signals at the same frequency wouldn't be disrupted. The Radio Technical Planning Board thus recommended that FM radio be relocated near 100 MHz. The Federal Communications Commission heeded the advice of the Radio Technical Planning Board and moved FM to the frequencies between 88 and 106 MHz on June 27, 1945. Later the Federal Communications Commission added the frequencies from 106 to 108 MHz which had been given to facsimile transmission but had never been used for that purpose. This change gave FM radio 100 channels whereas it only had 40 before, it also added to the number of reserved educational stations.
When in 1945 the Federal Communications Commission moved FM radio to the higher frequencies, it made all prewar FM radios worthless. The FM interests said it would cost $75,000,000 to convert and that it would set back the medium for years, which it did. Of course the FM interests fought back, Edwin Armstrong began fighting in 1944 to keep the frequencies FM already had. Armstrong went to court and to Congress, but lost in court and in a Congress that paid him lip service and little else. In 1945 when the change was ordered, there were already 55 pioneer FM stations on the air, and no nonexperimental television stations. The Federal Communications Commission had its most extensive hearings to that date, September 28 to November 2, 1944, on allocations decisions. When the Federal Communications Commission was making these decisions it had to balance several factors, but because of the wartime freeze it had time. The factors were the international responsibilities of the United States with the International Telecommunications Union (ITU), the American Armed Forces need for spectrum, television and FM desiring the same VHF band, and the competing television systems, color later on UHF and/or black and white now on VHF.
The FCC made later decisions that further hurt the acceptance of FM radio. One decison it made was to allow owners to own AM-FM combines in the same market. Eighty percent of FM stations were owned by AM station owners in the same market as an AM station of the owner. This lessoned the pursuit of FM stations for financial success because that would hurt profits from the AM station.
Duplication and simulcasting of programs was permitted by the Federal Communications Commission. This meant that AM and FM stations would often if not always play the same programs. The station break wording "You are listening to W(XYZ), AM and FM" was ubiquitous during the 1950s. Because of this there was even less reason to buy an FM receiver, and since no one could or would listen, advertisers wouldn't advertise. Since advertisers did not advertise the station made no money and little was spent on new programming. The vicious circle would not be broken for years to come.
(The chief exceptions to this occurred at the lower end of the dial, channels 201 through 220, 88.1 through 91.9. Radio broadcasting had been largely pioneered by colleges and universities. At the time of the Communications Act of 1934, there was intense debate about the degree to which the airwaves should be commercialized. The Act resolved this debate mostly in favor of commercial interests, and turned most of the airwaves over to commercial use. However, as a sop to the nonprofit interests and a compromise to achieve passage of the Act, it was agreed that a small portion of the broadcast spectrum would be reserved for nonprofit broadcasting by educational institutions. The ability to listen to college radio stations was however, hardly a compelling reason to purchase an FM receiver).
In Europe the FM radio broadcast was introduced in Germany after World War II. In 1948 a new wave-length plan was set up for Europe at a meeting in Copenhagen. Because of the recent war, Germany (who were not even invited) were only given a few medium-wave frequencies, which are not very good for broadcasting. For this reason Germany began broadcasting on USW, "ultra short wave" (nowadays called VHF). After some amplitude modulation experience with VHF, it was realized that FM radio was a much better alternative for VHF radio than AM.
In the 1960s, new technology was added to FM radio to allow FM stereo transmissions using a mono-compatible stereo multiplexing system.
Telex on Radio
Telegraphy did not go away on radio. Instead, the degree of automation increased. On land-lines in the 1930s, Teletypewriters automated encoding, and were adapted to pulse-code dialing to automate routing, a service called telex. For thirty years, telex was the absolute cheapest form of long-distance communication, because up to 25 telex channels could occupy the same bandwidth as one voice channel. For business and government, it was an advantage that telex directly produced written documents.
Telex systems were adapted to short-wave radio by sending tones over single sideband. CCITT R.44 (the most advanced pure-telex standard) incorporated character-level error detection and retransmission as well as automated encoding and routing.
For many years, telex-on-radio (TOR) was the only reliable way to reach some third-world countries. TOR remains reliable, though less-expensive forms of e-mail are displacing it. Many national telecom companies historically ran nearly pure telex networks for their governments, and they ran many of these links over short wave radio.
- Meteor scatter
- Moon bounce
- Nationwide networks
- Satellite transmission
Internet Radio (1995--)
The term "internet radio" is a misnomer: its consists of putting out radio-style audio programming over streaming Internet connections: no radio transmitters need be involved at any point in the process.
- Early technology wars: Push or pull, streaming media or multicast
- Run your own station with http://www.live365.com/ or almost like Geocities or Hotmail
Satellite Radio (2001--)
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