103 Remote Control-Mid

Remote Control FOCUS Question How do remote-controlled devices work?

Controlled from Afar There was a time, not so long ago, when you had to climb off your couch and walk to push buttons or turn a dial to change channels on your TV. But today you can channel surf from the comfort of your favorite chair. Remote control is everywhere. It can operate everything from music players to vacuum cleaners. We also use remote control to operate toy cars, toy planes, and drones. In 1898, the Electrical Exhibition was held in New York City's Madison Square Garden. Scientist Nikola Tesla showed off what was perhaps the first remote-controlled device He steered a metal model ship around a large container of water. Tesla's boat was an instant hit with the public Remote control had arrived!

Two Technologies There are two main types of remote control. One uses infrared waves to control objects that are nearby. The other uses radio waves that can control nearby objects as well as objects that are farther away. Infrared and radio waves are both types of electromagnetic energy. This type of energy travels away from a source in waves that move at the speed of light. Similar to visible light, infrared and radio waves can be identified by their wavelengths on the electromagnetic spectrum (see below). Wavelength is the distance between the peak of one wave and the peak of the wave next to it. But unlike visible light, we can't see these forms of energy.

Infrared Remote Control Most home remotes use infrared energy. You point the remote toward the object you want to control, such as a flat-screen TV, and push a button. The remote sends pulses of light from a light-emitting diode (LED). The object has a detector that picks up the pulses of light and then processes the information from the pulses. The pattern of light pulses tells the object what to do. Infrared technology is portable and requires little power— often just small batteries. Also, the light pulses aren't disrupted by signals from other devices. But infrared remotes only work over short distances, and people or walls can easily block the light pulses. The light must travel directly to the detector for the remote to work.

Many people use infrared light every day. Television remote controls use this technology. Infrared remotes can also control DVD players, CD players and other music players from a distance. Even some gaming systems use infrared. Their controllers use LEDs to communicate with a sensor bar to detect movement. Entertainment is not the only reason we use remote controls in our homes. These wireless devices can also operate home security and other systems, such as curtains and thermostats. If you feel tired, you could stay in bed and use an infrared remote control to close the curtains. Instant nap time!

Radio Remote Control Radio-controlled (RC) devices operate with radio wave technology. An RC remote control contains a transmitter that sends out radio waves to an object you want to operate. The radio waves travel at the speed of light! The object has a receiver that "catches" the signal. The receiver then interprets the signal and tells the object what to do. Radio waves work at longer ranges than infrared waves do. The receiver doesn't have to be in a direct line with the transmitter to work, just within range. And people or walls won't block the radio waves. However, other devices can interfere with radio waves and make it hard for the receiver to interpret the signal.