IR remote control

(InfraRed remote control) A handheld, wireless device used to operate audio, video and other electronic equipment within a room using light signals in the infrared (IR) range. Infrared light requires line of sight to its destination. Low-end remotes use only one transmitter at the end of the unit and have to be aimed directly at the equipment. High-quality remotes have three or four powerful IR transmitters set at different angles to shower the room with signals.

All Functions Are Coded
Using very low data rates, typically no more than 1,000 bits/sec, infrared remotes send a different code for each function on the TV, DVD, A/V receiver, etc. There are hundreds of remote control codes for the myriad of A/V devices manufactured over the years. A programmable remote may be customized by selecting built-in code sets, by downloading code sets from the Internet or by training the remote to accept signals from another remote.

IR Amplifiers Spread the Signals
In home theater applications, IR amplifiers, also known as "IR blasters," are commonly used to distribute signals to all the components, which is essential when they reside behind a closed cabinet door. A small sensor, placed at the TV or other convenient location for the user to aim at, is wired to the amplifier. The amplifier has ports for several emitters that are wired to, and pasted directly over, the IR sensors in the equipment.

RF to IR
High-end remote controls use radio frequencies (RF) instead of infrared (IR) because the unit neither has to be aimed, nor even be in the same room. In such cases, the RF is converted to IR in a base station and distributed to the equipment in the same manner as an IR amplifier. See RF remote control.

High-End IR Remote

The MX-850 from Universal Remote Control (www.universalremote.com) transmits IR and RF simultaneously. High-end remotes such as this use multiple IR transmitters for broad coverage. Programmed via the PC to make complex tasks easy, the green "M" keys have been assigned macros to power multiple units. The functions on the blue "L" keys were learned by beaming IR signals from the original remotes into the MX-850. See RF remote control.

An IR Emitter

An IR emitter (left) is pasted onto the IR sensor on this DVD/VHS player. The wire traces back to a Home Theater Master RF base station that picks up radio signals from the remote and converts them to infrared. No matter whether the remote control is IR or RF, the signal generally winds up as IR at the equipment.