Wireless Microphone - China Wireless Microphone Manufacturer

Wireless Microphone - China Wireless Microphone Manufacturer

Wireless Microphone WebSite Link:
http://www.chinese-microphone.com/Wireless-Microphones.html

China GuangZhou TianTuo Microphone Manufacturing Co., Ltd WebSite:
http://www.chinese-microphone.com/


Microphone Products are: Wireless Microphones, Conference Microphones,
Headset Microphones, and Lapel Microphones, interview microphones,
wired microphones, musical instrument microphones, drum microphones,
teaching microphones, recording microphones, computer's USB
microphones and microphone accessories and So on.




Wireless microphone - Wikipedia, the free encyclopedia Wireless
microphone From Wikipedia, the free encyclopedia Jump to: navigation,
search Please help improve this article or section by expanding
it.Further information might be found on the talk page or at requests
for expansion. (January 2007)A wireless microphone, as the name
implies, is a microphone without a physical cable connecting it
directly to the sound recording or amplifying equipment with which it
is associated.Various individuals and organizations claim to be the
inventors of th http://www.chinese-microphone.com/Wireless-Microphones.html
e Wireless Microphone.John F. Stephens developed an FM wireless
microphone for a Navy musical show in 1951 on the Memphis Naval base.
Each of the principal players/singers had their own microphone/
transmitter. Subsequently, the Secret Service had Stephens modify his
invention to be used in government "bugging" operations. In the '60s,
Stephens marketed his more famous capstanless multitrack recorder/
reproducers.Shure Incorporated claim that their "Vagabond" system from
1953 was the first.In 1957 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.Another German equipment
manufacturer, Beyerdynamic, claim that first wireless microphone, was
invented by Hung C. Lin. Called the "transistophone", it went into
production in 1962. It is claimed that the first time a wireless
microphone was used to record sound during filming of a motion picture
was on Rex Harrison in the 1964 film My Fair Lady.Modern wireless
microphone technology, which for the first time offered performance
with audio and dynamic range equivalent to a cord, originated with the
introduction of the first compander wireless microphone offered by
Nady Systems, Inc in 1976 according to company claims. Nady systems,
Inc was honored with an Emmy award for this breakthrough technical
achievement in 1996.More commonly known as a Radio Microphone, 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
radiowaves using UHF or VHF frequencies, FM, AM, or various digital
modulation schemes. Some low cost 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 tim

e.Contents1 Advantages and disadvantages2 Techniques3 Products4
Bandwidth and Spectrum4.1 Digital5 Licensing6 External links[edit]
Advantages and disadvantagesWireless microphones awaiting pickup by
performers in a musical.The advantages are:The freedom of movement for
the artist or speaker.Avoidance of cabling problems common with wired
microphones, caused by constant moving and stressing the cables.The
disadvantages are:Sometimes limited range (a wired balanced XLR
microphone can run up to 300 ft or 100 meters). Some wireless systems
have a shorter range, while more expensive models can exceed that
distance.Possible interference with other radio equipment or other
microphones, though models with many frequency-synthesized switch-
selectable channels are now plentiful and cost effective.Limited
operation time due to battery life.Noise or dead spots (places where
it doesn't work, in non-diversity systems)Limited number of operating
microphones at the same time and place, due to the limited number of
radio channels ( http://www.chinese-microphone.com/Wireless-Microphones.html
frequencies).[edit] TechniquesThe professional models transmit in VHF
or UHF radio frequency and have 'true' diversity reception (two
separate receiver modules each with its own antenna), which eliminates
dead spots (caused by phase cancellation) and the effects caused by
the reflection of the radiowaves on walls and surfaces in general.
(See antenna diversity).Another technique used to improve the sound
quality (actually, to improve the dynamic range), is companding. Nady
Systems, Inc was the first to offer this technology in wireless
microphones in 1976, which was based on the patent obtained by company
founder John Nady.Some models have adjustable gain on the microphone
itself, to be able to accommodate different level sources, such as
loud instruments or quiet voices. Adjustable gain helps to avoid
clipping.Some models have adjustable squelch, which silences the
output when the receiver does not get a strong or quality signal from
the microphone, instead of reproducing noise. When squelch is
adjusted, the threshold of the signal quality or level is adjusted.
[edit] ProductsElectro-Voice, Shure, Nady Systems, Inc, Sennheiser,
Lectrosonics, Samson Technologies, AKG Acoustics MIPRO and Audio-
Technica are all major manufacturers of wireless microphone systems.
They have made significant advances in dealing with many of the
disadvantages listed above. For example, while there is a limited band
in which the microphones may operate, the new UHF-R series from Shure
can have up to 108 different microphones operating simultaneously.
However, allowing more microphones to operate at the same time
increases the cost. That is one reason for such large price
differences between different series of wireless systems. The audio
quality has also greatly improved as newer systems have become
available.Generally there are two wireless microphone types: handheld
and bodypack:Handheld is like a normal microphone, but it has a bigger
body to accommodate the transmitter and battery pack.Bodypack is a
small box housing the transmitter and battery pack, but not the
microphone itself. It is attachable to belt or elsewhere and has a
wire going to headset, lavalier microphone or a guitar.Several
manufacturers including Sennheiser, AKG, Nady Systems, Lectrosonics
and Zaxcom offer a plug-on transmitter for existing wired microphones,
which plugs into the XLR output of the microphone and transmits to the
manufacturer's standard receiver. This offers many of the benefits of
an integrated system, and also allows microphone types (of which there
may be no wireless equivalent) to be used without a cable. For example
a television, or film, sound production engineer may use a plug-on
transmitter to enable wireless transmission of a highly directional
rifle (or "shotgun") microphone, removing the safety hazard of a cable
connection and permitting the production engineer greater freedom to
follow the action. Plug-in transmitters also allow the conversion of
vintage microphone types to cordless operation. This is useful where a
vintage microphone is needed for visual or

other artistic reasons, and the absence of cables allows for rapid
scene changes and reducing trip hazards. In some cases these plug-on
transmitters can also provide 48 volt phantom power allowing the use
of condenser microphone types. DC-DC converter circuitry within the
transmitter is used to multiply the battery supply, which may be three
volts or less, up to the required 48 volts.There are three main types
of receiver, available in two main types of housing. True Diversity
receivers have two radio modules and two antennas. Diversity receivers
have one radio module and two antennas. Non-diversity modules have one
antenna.Receivers are commonly housed in a half-rack configuration, so
that two can be mounted together in a rack system. For large complex
multi channel radio microphone systems, as used in broadcast
television studios and musical theater productions, modular receiver
systems with several (commonly eight) true diversity receivers
slotting into a rack mounted mainframe housing are available. Several
mainframes may be used together in a rack to supply the number of
receivers required. In some musical theater productions, systems with
forty or more radio microphones are not unusual.Receivers
http://www.chinese-microphone.com/Wireless-Microphones.html
specifically for use with video cameras are often mounted in a
bodypack configuration, typically with a hotshoe mount to be fitted
onto the hotshoe of the camcorder. Small true diversity receivers
which slot in to a special housing on many professional broadcast
standard video cameras are produced by manufacturers including
Sennheiser and Sony. For less demanding or more budget conscious video
applications small non-diversity receivers are common. When used at
relatively short operating distances from the transmitter this
arrangement gives adequate and reliable performance.[edit] Bandwidth
and SpectrumAlmost all wireless microphone systems use wideband FM
modulation, which requires approximately 200 kHz of bandwidth to
operate in. Because of the relatively large bandwidth requirements,
wireless microphone use is effectively restricted to VHF and
above.Many older wireless microphone systems operate in the VHF part
of the electromagnetic spectrum. Systems operating in this range are
often crystal-controlled, and therefore operate on a single frequency.
However, if this frequency is chosen properly, the system will be able
to operate for years without any problems.Most modern wireless
microphone products operate in the UHF television band, however. In
the United States, this band extends from 470 MHz to 806 MHz. Other
countries have similar band limits; for example, Great Britain's UHF
TV band extends from 470 MHz to 854 MHz. Typically, wireless
microphones operate on unused TV channels, with room for one to two
microphones per MHz of spectrum available. Starting in January of 2009
UHF channels for wireless microphones will be limited to below 695MHz,
due to the FCC auctioning the "white space" frequencies between
695-806MHz for other uses.Intermodulation (IM) is a major problem when
operating multiple systems in one location. IM occurs when two or more
RF signals mix in a non-linear circuit, such as an oscillator or
mixer. When this occurs, predictable combinations of these frequencies
can occur. For example, the combinations 2A-B, 2B-A, and A+B-C might
occur, where A, B, and C are the frequencies in operation. If one of
these combinations is close to the operating frequency of another
system (or one of the original frequencies A, B, or C), then
interference will result on that channel. The solution to this problem
is to manually calculate all of the possible products, or use a
computer program that

does this calculation automatically.[edit] DigitalThere are two
commonly-used digital transmission schemes in use today: Digital
Hybrid and Pure Digital.Digital Hybrid systems use an analog FM audio
signal in combination with digital signal processing (DSP) to enhance
the system's audio. Using DSP, it is easier to achieve a flat
frequency response in the audio spectrum and to reduce noise and other
undesirable effects. Since the audio is transmitted via FM, these
systems use 200-500 kHz of bandwidth.Pure Digital systems may tak
http://www.chinese-microphone.com/Wireless-Microphones.html e various
forms, but many systems use frequency-hopping spread spectrum
technology, similar to that used for cordless phones. As this requires
more bandwidth than an FM signal, these microphones operate in the 900
MHz or 2.4 GHz unlicensed bands. Unfortunately, this results in
interference to and from wireless computer networks, Bluetooth
devices, cordless phones, amateur radio operators, and many other
things.[citation needed]Manufacturers that offer digital wireless
microphone systems include Audio-Technica, Lectrosonics, MIPRO,
Sabine, Sony, and Zaxcom.[edit] LicensingIn the UK, use of wireless
microphone systems requires a license, except for the license free
bands of 173.8 MHz - 175.0 MHz and 863 MHz - 865 MHz (N.B. This is
emphatically NOT TV Channel 69. Channel 69 is from 854 - 862 MHz. In
the UK Channel 69 frequencies do require a license from JFMG Ltd.:
[1] ).The UK communications regulator, Ofcom, has said it will auction
part of the spectrum currently reserved for wireless microphones, to
which objections have been raised by Andrew Lloyd Webber. [2]
[3]Licenses are required to use wireless microphones on vacant TV
channels in the United States as they are a part of the Broadcast
Auxiliary Service (BAS). However, this requirement is often overlooked
and rarely enforced by the FCC.In many other countries wireless
microphone use requires a license. Some governments regard all radio
frequencies as military assets and the use of unlicensed radio
transmitters, even wireless microphones, may be severely punished.
[edit] External linksDiscussion regarding the reassignment of Channel
69 frequencies in the UKRetrieved from "http://en.wikipedia.org/wiki/
Wireless_microphone" Categories: MicrophonesHidden
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