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A wireless microphone is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Also known as a radio microphone, it has a small, battery-powered radio transmitter in the microphone body, which transmits the audio signal from the microphone by radio waves to a nearby receiver unit, which recovers the audio. The other audio equipment is connected to the receiver unit by cable. Wireless microphones are widely used in the entertainment industry, television broadcasting, and public speaking to allow public speakers, interviewers, performers, and entertainers to move about freely while using a microphone to amplify their voices. There are many different standards, frequencies and transmission technologies used to replace the microphone's cable connection and make it into a wireless microphone. They can transmit, for example, in radio waves using UHF or VHF frequencies, FM, AM, or various digital modulation schemes. Some low cost (or specialist) models use infrared light. Infrared microphones require a direct line of sight between the microphone and the receiver, while costlier radio frequency models do not. Some models operate on a single fixed frequency, but the more advanced models operate on a user selectable frequency to avoid interference and allow the use of several microphones at the same time. ==History== Various individuals and organizations claim to be the inventors of the wireless microphone. From about 1945 there were schematics and hobbyist kits offered in ''Popular Science'' and ''Popular Mechanics'' for making a wireless microphone that would transmit the voice to a nearby radio. Figure skater and Royal Air Force flight engineer Reg Moores developed a radio microphone in 1947 that he first used in the Tom Arnold production "Aladdin on Ice" at Brighton's sports stadium from September 1949 through the Christmas season. Moores affixed the wireless transmitter to the costume of the character Abanazar, and it worked perfectly. Moores did not patent his idea, as he was illegally using the radio frequency 76 MHz. The producers of the ice show decided that they would not continue using the device; they would rather hire actors and singers to perform into hidden microphones to "dub" the voices of the other ice skaters, who would thus be free to concentrate on their skating. In 1972 Moores donated his 1947 prototype to the Science Museum in London. Herbert "Mac" McClelland, founder of McClelland Sound in Wichita, Kansas, fabricated a wireless microphone to be worn by baseball umpires at major league games broadcast by NBC from Lawrence-Dumont Stadium in 1951.〔McClelland Sound (History: 1940–1950. ) Retrieved on January 14, 2010.〕 The transmitter was strapped to the umpire's back. Mac's brother was Harold M. McClelland, the chief communications architect of the U.S. Air Force. Shure Brothers claims that its "Vagabond" system from 1953 was the first "wireless microphone system for performers."〔(【引用サイトリンク】title=History )〕 Its field of coverage was a circle of "approximately 700 square feet," which corresponds to a line-of-sight distance of only from the receiver.〔 In 1957 the German audio equipment manufacturer Sennheiser, at that time called Lab W, working with the German broadcaster Norddeutscher Rundfunk (NDR), exhibited a wireless microphone system. From 1958 the system was marketed through Telefunken under the name of Mikroport. The pocket-sized Mikroport incorporated a dynamic moving-coil cartridge microphone with a cardioid pickup pattern. It transmitted at 37 MHz with a specified range of . The first recorded patent for a wireless microphone was filed by Raymond A. Litke, an American electrical engineer with Educational Media Resources and San Jose State College, who invented a wireless microphone in 1957 to meet the multimedia needs for television, radio, and classroom instruction. His U.S. patent number 3134074 was granted in May 1964. Two microphone types were made available for purchase in 1959: hand-held and lavalier. The main transmitter module was a cigar-sized device which weighed . The Federal Communications Commission (FCC) granted Litke twelve frequencies at his approval hearing. It was first tested at the Olympic trials held at Stanford University in 1959. Vega Electronics Corporation manufactured the design later that year, producing it as a product called the Vega-Mike. The device was first used by the broadcast media at the 1960 Democratic and Republican National Conventions. It allowed television reporters to roam the floor of the convention to interview participants, including presidential candidates John F. Kennedy and Richard Nixon, who spoke into the wireless microphone. Television anchor John Daly praised the microphone during a TV news broadcast in July 1960. Introduced in 1958, the Sony CR-4 wireless microphone was being recommended as early as 1960 for theatre performances and nightclub acts. Animal trainers at Marineland of the Pacific in California were wearing the $250 device for performances in 1961. The 27.12 MHz solid-state FM transmitter was capable of fitting into a shirt pocket. Said to be effective out to , it mounted a flexible dangling antenna and a detachable dynamic microphone. The tube-based receiver incorporated a carrying drawer for the transmitter and a small monitor loudspeaker with volume control. Another German equipment manufacturer, Beyerdynamic, claims that the first wireless microphone was invented by Hung C. Lin. Called the "transistophone," it went into production in 1962. The first time that a wireless microphone was used to record sound during filming of a motion picture was allegedly on Rex Harrison in the 1964 film ''My Fair Lady'', through the efforts of Academy Award-winning Hollywood sound engineer George Groves.〔George Groves Sound History (Making of My Fair Lady. ) Retrieved on February 1, 2011.〕 Wider dynamic range came with the introduction of the first compander wireless microphone, offered by Nady Systems in 1976. Todd Rundgren and The Rolling Stones were the first popular musicians to use these systems live in concert. Nady joined CBS, Sennheiser and Vega in 1996 to receive a joint Emmy Award for "pioneering () development of the broadcast wireless microphone". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wireless microphone」の詳細全文を読む スポンサード リンク
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