Accessorize: A Remote-Control Primer
At one time, "changing the channel" meant walking over to the television and turning a knob. Now it means pressing a button or tapping a graphical icon on a touch-screen remote control.
The earliest remote controls were connected to the TV set by a wire. To overcome this unsightly inconvenience, Zenith Radio, in the 1950s, developed a wireless remote that used a beam of light to convey control signals. This technology was soon surpassed by a new wireless system that used ultrasonic sound waves.
Dr. Robert Adler, along with Eugene Polly, developed the "Space Command" ultrasonic remote control system for Zenith. It performed four simple functions: On/Off, Sound On/Sound Off, Channel Up and Channel Down by transmitting sounds at specific frequencies. When activated, it made a clicking noise, hence the nickname "clicker."