What Is an IR Transmitter and Receiver?

Jeremy Laukkonen

Infrared (IR) transmitters and receivers are present in many different devices, though they are most commonly found in consumer electronics. The way this technology works is that one component flashes an infrared light in a particular pattern, which another component can pick up and translate into an instruction. These transmitters and receivers are found in remote controls and all different types of devices, such as televisions and DVD players. Peripheral devices that include this technology can also allow a computer to control various other consumer electronics. Since infrared remotes are limited to line of sight operation, some products can be used to extend the signals over a hardwired line or radio frequency (RF) transmissions.

IR transmitters and receivers are found in all types of devices, such as DVD players.
IR transmitters and receivers are found in all types of devices, such as DVD players.

Most common consumer electronic remote controls use infrared light. They typically generate infrared using light emitting diodes (LEDs), and the main component of a receiver unit is usually a photodiode. A remote control flashes a pattern of invisible light, which is picked up and then turned into an instruction by the receiver module. The parts necessary to construct transmitter and receiver are typically inexpensive, but these systems are limited to line of sight operation.

TV remote control with an IR transmitter.
TV remote control with an IR transmitter.

In order to extend the range of a typical infrared remote control beyond line of sight, it is possible to combine an IR transmitter and receiver with another component. A hardwired extender unit uses a transmitter and receiver that are connected by a physical wire. This wire can be routed around or through a wall, with the transmitter located in one room and the receiver in another. When a signal is sent to the receiver from a remote control, it travels across the wire and is then turned back into infrared light by the transmitter at the other end.

Radio frequency IR extenders perform this same function without any physical wires. These systems involve two components, one of which contains an IR receiver and an RF transmitter. The paired unit contains an RF receiver and IR transmitter. When an infrared remote is used on the IR receiver, the device translates the signal and broadcasts it over RF. The paired unit then receives that signal, decodes it and transmits an IR signal.

Infrared transmitter and receiver devices can also be used with some computers. These peripherals are typically designed to connect via universal serial bus (USB) and can be used to control various types of consumer electronics. Software can allow the devices to learn commands directly from other remote controls.

The main component of a receiver unit is usually a photodiode.
The main component of a receiver unit is usually a photodiode.

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Discussion Comments


@StarJo – That's because it uses infrared light, and we can't see this kind. It just travels through the air unseen.

If someone walks between the remote and the TV, then the light gets interrupted and you can't change the channel until the person has moved. Also, if any furniture is in the way, you'll have to move it, because infrared light can't travel through it.

However, I do remember a cool trick I learned in physics. If you stand in the room with a mirror in your hand and adjust it so that you can see the screen in it and then aim the remote at the mirror image, the remote will work. This is because the light bounces off the surface and gets redirected toward the screen.


It's pretty cool that a signal can travel through a wire and convert back into light at the end. I don't understand the specifics, but it's a neat trick, anyway.


You know, I have noticed that when I press a button on my TV remote, a little red light flashes at the end of it facing the TV. I think it's weird that I can't see a ray of light going across the room. It is bright enough to turn the end of my remote red, but somehow, it's invisible in the air.

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