Remote control is a technique of operating a system from a distance. The operating system may range from a television set to a guided missile, and the distance may range from a few metres to a few hundred kilometres.
There are different kinds of remote control depending on the way the command unit sends signals to the operating system. Most command units send signals by infrared, radio waves, lasers or ultrasonic waves. Some even use mechanical arms.
The common TV or VCR remote controls use coded infrared pulses. A tiny receiver in the TV set or VCR decodes the signal and activates the appropriate operation.
A typical radio remote control unit transmits radio signals to a receiver set in the device to be operated which are then decoded and the information sent to the electronic circuit or electric motors which operate the device.
In laser controlled missiles, guided signals are transmitted to a missile along a beam of laser which tracks the missile during flight. Mechanical remote control provides a safe method of handling radio-active materials and other dangerous substances.
