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Wireless microphone
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Wireless microphone
A wireless microphone, or cordless 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. In one type the transmitter is contained within the handheld microphone body. In another type the transmitter is contained within a separate unit called a "bodypack", usually clipped to the user's belt or concealed under their clothes. The bodypack is connected by wire to a "lavalier microphone" or "lav" (a small microphone clipped to the user's lapel), a headset or earset microphone, or another wired microphone. Most bodypack designs also support a wired instrument connection (e.g. to a guitar). 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 without requiring a cable attached to the microphone.
Wireless microphones usually use the VHF or UHF radio frequency bands since they allow the transmitter to use a small unobtrusive antenna. Cheap units use a fixed frequency but most units allow a choice of several frequency channels, in case of interference on a channel or to allow the use of multiple microphones at the same time. Frequency modulation is usually used, although some models use digital modulation to prevent unauthorized reception by scanner radio receivers; these operate in the 900 MHz, 2.4 GHz or 6 GHz ISM bands. Some models use antenna diversity (two antennas) to prevent nulls from interrupting transmission as the performer moves around. A few low cost (or specialist) models use infrared light, although these require a direct line of sight between microphone and receiver.
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. 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 88 system from 1953 was "the first handheld wireless microphone system for performers." Its transmitter used five subminiature vacuum tubes and could cover an area from 500 to 5,000 square feet (46 to 465 m2) (a line-of-sight distance of 15 to 40 feet (4.6 to 12.2 m) from the receiver, depending on local electromagnetic interference), using FM at a carrier frequency of 2.1 MHz. At about the same time, Donald E. Thomas at Bell Labs described an experimental transmitter that used a single point-contact transistor as both oscillator and modulator and whose signal could be picked up by any commercial FM 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 300 feet (90 m).
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Wireless microphone
A wireless microphone, or cordless 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. In one type the transmitter is contained within the handheld microphone body. In another type the transmitter is contained within a separate unit called a "bodypack", usually clipped to the user's belt or concealed under their clothes. The bodypack is connected by wire to a "lavalier microphone" or "lav" (a small microphone clipped to the user's lapel), a headset or earset microphone, or another wired microphone. Most bodypack designs also support a wired instrument connection (e.g. to a guitar). 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 without requiring a cable attached to the microphone.
Wireless microphones usually use the VHF or UHF radio frequency bands since they allow the transmitter to use a small unobtrusive antenna. Cheap units use a fixed frequency but most units allow a choice of several frequency channels, in case of interference on a channel or to allow the use of multiple microphones at the same time. Frequency modulation is usually used, although some models use digital modulation to prevent unauthorized reception by scanner radio receivers; these operate in the 900 MHz, 2.4 GHz or 6 GHz ISM bands. Some models use antenna diversity (two antennas) to prevent nulls from interrupting transmission as the performer moves around. A few low cost (or specialist) models use infrared light, although these require a direct line of sight between microphone and receiver.
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. 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 88 system from 1953 was "the first handheld wireless microphone system for performers." Its transmitter used five subminiature vacuum tubes and could cover an area from 500 to 5,000 square feet (46 to 465 m2) (a line-of-sight distance of 15 to 40 feet (4.6 to 12.2 m) from the receiver, depending on local electromagnetic interference), using FM at a carrier frequency of 2.1 MHz. At about the same time, Donald E. Thomas at Bell Labs described an experimental transmitter that used a single point-contact transistor as both oscillator and modulator and whose signal could be picked up by any commercial FM 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 300 feet (90 m).
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