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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.
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 radio waves 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 time.
Almost all wireless microphone systems use wideband FM modulation, requiring
approximately 200 kHz of bandwidth. 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.
Wireless
microphone is one of an analog
electronic circuits, analog electronic circuits are those in which signals may vary continuously with time
to correspond to the information being represented. Electronic equipment like
voltage amplifiers, power amplifiers, tuning circuits, radios, and televisions
are largely analog (with the exception of their control sections, which may be
digital, especially in modern units).
In digital
electronic circuits, electric signals take on discrete values, which are not
dependent upon time, to represent logical and numeric values. These values
represent the information that is being processed. The transistor is one of the
primary components used in discrete circuits, and combinations of these can be
used to create logic gates. These logic gates may then be used in combination to
create a desired output from an input. In this page you can find one of the
circuit.
Wireless Microphone
Dengan sedikit komponen, kita dapat bereksperimen membangun suatu
mikrofon nirkabel yang cukup bermanfaat, rangkaiannya adalah seperti pada
Gambar 1.

Gambar 1. Rangkaian Wireless Microphone.

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