InfraRed Communication and Device or Peripheral Control.
Posted: Friday, September 09, 2005
by Seamus
http://www.CountControl.com
Firstly, infra is more or less the opposite of ultra, and light is not necessarily visible to the human eye.
(Incidentally, Elephants have been found to communicate by infra sound as well, which can be felt more so than heard).
Anyway, the first common application of infrared light communication would have been the remote control for a typical T.V.
Its primary advantage was convenience and some limited portability. No cabling to lose, as well, lol.
Line of sight and distance, with respect to infrared, is a limiting factor and radio waves can continue after they meet an object, making that choice more versatile over longer distances.
Having said that, devices to extend the portability of infra red transmitters and receivers, are widely available but still limited. They are still fine for most domestic applications.
How infrared communication works is like this:
- Use a light transmitter to transmit the infrared light (diode or laser diode or fast reacting and stable light bulbs, if you like).
- Use a light receiver (photo-resistor, or something to respond to the infrared light pulses, if you like).
- You must have a power source (a battery, normally) for the more portable end and the less portable end.
The length in time of the light pulse, determines the information or data sent and received.
As diodes and lasers are designed to be predictable or somewhat coherent light sources (infrared, in this case), their on and off states can taken to be reliable enough for the purposes that they are intended for.
The photo resistors are also reliable enough, and their electrical resistances are changed by exposures to such light.
Changes in electrical resistance can then be made to manipulate or vary, other sections of the circuitry.
In essence, it has the same result as exerting a physical force on a analogue switch, but you don’t need to be near the less portable device or its switch. You don't need to exert the same effort, either.
That's infrared communication!
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