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How Remote Controls Work?

 post:2016-09-09


 The world's first remote controls were radio-frequency devices that directed German naval vessels to crash into Allied boats during WWI. In WWII, remote controls detonated bombs for the first time. The end of the great wars left scientists with a brilliant technology and nowhere to apply it. Sixty years later, some of us spend an hour looking for the remote before we remember there are buttons on the TV.

  The dominant remote-control technology in home-theater applications is infrared (IR). Infrared light is also known as plain-old "heat." The basic premise at work in an IR remote control is the use of light to carry signals between a remote control and the device it's directing. Infrared light is in the invisible portion of the electromagnetic spectrum.

  An IR remote control (the transmitter) sends out pulses of infrared light that represent specific binary codes. These binary codes correspond to commands, such as Power On/Off and Volume Up. The IR receiver in the TV, stereo or other device decodes the pulses of light into the binary data (ones and zeroes) that the device's microprocessor can understand. The microprocessor then carries out the corresponding command.

  Radio-frequency (RF) remote controls are very common. Garage-door openers, car-alarm fobs and radio-controlled toys have always used radio remotes, and the technology is starting to show up in other applications, too. They're still pretty rare in home-theater devices (with the exception of RF extenders, which we'll discuss on the next page), but you will find RF remotes controlling certain satellite-TV receivers and high-end stereo systems. You'll also find Bluetooth-based remotes that control laptops and smartphones.

  Instead of sending out light signals, an RF remote transmits radio waves that correspond to the binary command for the button you're pushing. A radio receiver on the controlled device receives the signal and decodes it. The problem with RF remotes is the sheer number of radio signals flying through the air at any given time. Cell phones, walkie-talkies, WiFi setups and cordless phones are all transmitting radio signals at varying frequencies. RF remotes address the interference issue by transmitting at specific radio frequencies and by embedding digital address codes in the radio signal. This lets the radio receiver on the intended device know when to respond to the signal and when to ignore it.

  Different electronics brands use different command codes. Some IR remotes are preprogrammed with more than one manufacturer's command codes so they can operate multiple devices (sometimes up to 15) of different brands. If your home-theater setup incorporates components from, say, three different manufacturers, you can either use three different remotes to operate your system or use one universal remote. To add functions to a universal remote, you need to know the command codes for the component you want to control. You can look these up online or find them in the manual that came with your remote.

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Keywords:How Remote Controls Work,Remote Controls Work,Remote Controls
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