For a Telecommand (TC) to be effective, it must be compiled into a pre-arranged format (which may follow a standard structure), modulated onto a carrier wave which is then transmitted with adequate power to the remote system. The remote system will then demodulate the digital signal from the carrier, decode the TC, and execute it. Transmission of the carrier wave can be by ultrasound, infra-red or other electromagnetic means.
Infrared Infrared light makes up the invisible section of the
electromagnetic spectrum. This light, also classified as heat, transmits signals between the transmitter and receiver of the remote system. When the buttons on a remote are pressed they touch and close their corresponding contacts below them within the remote. There are four aluminum rods inside the transmitter that produce high frequency sounds when they are hit at one end. Each rod is a different length, which enables them to produce varying sound pitches, which control the receiving unit. This technology was widely used but had certain issues such as dogs being bothered by the high frequency sounds. == New applications ==