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Infrared (IR) technology makes up the bulk of the remote device operation market. An IR controller sends coded infrared waves to an IR receiver, where they are translated into device commands. This technology is best known in the household remote control, the device that remotely operates nearly every home entertainment device from the mid-1980s on. In addition to televisions, an IR controller can operate nearly anything that accepts digital commands, ranging from home appliances to automobiles and computer systems.
The technology behind an IR controller is deceptively simple. When a button is pressed on the remote control, a panel on the device emits a short burst of infrared light. This light is invisible to humans; it is just outside of visible light. A receiver on the connected device will read the invisible flashes and translate them into a command. In many ways, this works like Morse code, a selection of long a short pulses that correspond to a command.
Since the technology functions via invisible light, it has some of the same properties as visible light. The burst emitted by the IR controller needs to be in place where the receiver can see it. If solid objects block either of the parts, the signal cannot pass and the command will not execute. On the other hand, properly positioned mirrors will allow the light to bend around walls and into other rooms.
When an IR controller is able to penetrate walls, or other solid objects, it is probably not solely IR. Since IR is only light, it can’t do anything that light can’t do. When a remote needs to have additional functions, it will usually include a radio transmitter. In this case, the system will recognize that the signal is not reaching the receiver and emit a short radio burst that mimics the IR signal. This signal will penetrate objects and travel much further than standard IR.
In order to keep an IR controller from interfering with other devices, manufacturers install different codes into different systems. This basically means that all of the remote-enabled devices speak different languages. When a receiver sees a command that it doesn’t recognize, it will simply ignore it. This opens the way to programmable remotes; essentially, they can learn the language spoken by other devices, allowing one IR controller to perform the job of several.
An IR controller only works on digital devices. If a system has an onboard computer system, it can use the technology; devices without digital systems can’t. Some manufacturers will put digital receivers within analog devices as an intermediary to allow IR communication. In these devices, the remote creates a digital response that activates an analog function — it does not directly interact with the analog system.