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Remote Controls Information
 With
most pieces of consumer electronics, from camcorders to stereo equipment, an
infrared remote control is usually always included. Video and audio apparatus,
computers and also lighting installations nowadays often operate on infra-red
remote control.The carrier frequency of such infra-red signals is typically in
the order of around 36 kHz. The control codes are sent in serial format
modulated to that 36 kHz carrier frequency (usually by turning the carrier on and
off). There are many different coding systems in use, and generally different
manufacturers use different codes and different data rates for transmission.
 "IR" stands for
infrared. Infrared light is invisible since its frequency is below that of
visible red. Otherwise, it is like any other light source, operating under the
same laws of physics. In
most cases, the IR signals are produced by an LED source.
IR transmit and receive
systems are inexpensive and are generally reliable. However, interference from
other IR sources can be a minor issue. Interference can come from IR remote
controls, IR audio systems (these broadcast an IR signal continuously) or other
IR sources. Interference can also be caused by other light sources such as
fluorescent lights (the ballast can cause IR interference). Sometimes some
electronic ballasts powered light can cause interference problems. In order to  avoid
any interference with this kind of equipment, the operating frequency of all
electronic ballasts has to be chosen so that problems in the 36 kHz frequency
area are out of the question.
Many existing IR systems
modulate the IR light at around 36-40 kHz (this is the frequency of the IR
carrier and should not to be confused with the actual frequency of the IR light
itself). The possibility of interference is more likely around the 40 kHz
frequency. One way to limit interference is to use higher IR carrier
frequencies. Some IR systems now use carrier frequencies into the megahertz
region.
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