Infrared

Infrared

Infrared signals with frequencies ranges from 300 GHz to 400 GHz can be used for short range communication. Infrared signals, having high frequencies, cannot penetrate walls. This helps to prevent interference between one system and another. Infrared Transmission in one room cannot be affected by the infrared transmission in another room.
» Unguided infrared and millimeter waves are widely used for short-range communication.
» The remote controls used on televisions, VCRs, and stereos all use infrared communication.
» They are relatively directional, cheap, and easy to build but have a major drawback: they do not pass through solid objects (try standing between your remote control and your television and see if it still works).
» In general, as we go from long-wave radio toward visible light, the waves behave more and more like light and less and less like radio.
» On the other hand, the fact that infrared waves do not pass through solid walls well is also a plus.

» It means that an infrared system in one room of a building will not interfere with a similar system in adjacent rooms or buildings.
» Furthermore, security of infrared systems against eavesdropping is better than that of radio systems precisely for this reason.
» Therefore, no government license is needed to operate an infrared system, in contrast to radio systems, which must be licensed outside the ISM bands.