How Does a Remote Control Work?

Remote controls have been a part of people’s life for a long time. In World War I and World War II, explosive devices and boats were controlled by radio-frequency devices that could make these work remotely. Then, science evolved, and now every kind of electronic device can run with remote control.

In the present time, there are usually two primary kinds of technology that remote control is based on Radio Frequency technology (RF) and Infrared technology (IR).

Infrared technology is dominantly used in home theatre and TV devices. A transmitter or the IR remote uses light for carrying the signal from the remote control to the device/gadget it controls. Pulses of an invisible IR light are emitted to correspond to the binary codes. These are specific codes representing commands like volume down, power off, channel up, etc. The IR light pulses are decoded into binary codes by the receiver or controlled device/gadget to understand the internal microprocessor. After decoding the signals, commands are executed by the microprocessor.

The IR remotes use LED lights for transmitting the infrared signal. This leads to some technical limitations as well. As light is used for transmitting signals, IR remotes need line-of-sight, an open way between a transmitter and its receiver. Hence, IR remotes fail to work around corners or across walls. Moreover, their range is not more than 30 feet.

Radio-frequency remotes do not use infrared lights to send a signal. Instead, their binary codes are transmitted through radio waves. It enables the RF remotes to have a way high range than that of the IR remotes. The former can have a range of 100 feet and, at times, even more. Thanks to this, they are usually used in applications such as car alarms and door openers. These days, RF remotes come with various modern satellite TV systems as well. See Why does the PlayStation move controller change colour?

We need to remember that RF technology has issues of its own. Even though they have a way better range than IR remotes, RF remotes might have to tackle interference as we are all surrounded by a huge number of radio waves at all times. For example, a cell phone and a wireless internet both function through radio signals.

For dealing with this issue, many radio-frequency remotes transmit a signal only at specific frequencies. For ensuring a receiver is only responding to the right radio signals, they are also embedding digital address codes within their radio signals.