Today’s Wonder of the Day was inspired by Jaiden. Jaiden Wonders, “How Do TV Remotes Work” Thanks for WONDERing with us, Jaiden!
Have you ever had older parents or relatives tell you about how much rougher their lives were back in the "good ol' days"? You may have heard apocryphal stories of having to walk to and from school…uphill…both ways…in a foot of snow!
Before you dismiss these stories as nothing more than old wives' tales, take a moment to consider that life a few decades ago might indeed have been more difficult than it is today. For example, decades ago your older parents and relatives couldn't simply "Google" the answer to any question they might have.
Instead, they had to do research with real books! Can you imagine? If that amazes you, you'll be really surprised by how different it was to watch television. In addition to having only a dozen channels rather than hundreds, they also had to walk across the room to turn a knob on the television set if they wanted to change channels!
Today, all you need to do is push a button on the remote control to flip back and forth between hundreds of channels. In fact, many of the things you use every day can probably be controlled remotely. From garage door openers and toy cars to lights and stereo equipment, it's easier than ever to control things from a distance.
Remote control has actually been around a long time. In both World War I and World War II, radio-frequency devices were used to control boats and explosive devices remotely. Eventually, scientists would figure out how to incorporate that technology into all sorts of electronic devices.
Today, remote control devices are usually based upon one of two main types of technology: infrared (IR) technology or radio frequency (RF) technology. Let's look at how these types of technology help you control devices from afar.
When it comes to televisions and home theater devices, the dominant technology tends to be infrared. An IR remote (also called a transmitter) uses light to carry signals from the remote to the device it controls. It emits pulses of invisible infrared light that correspond to specific binary codes.
These codes represent commands, such as power on, volume up, or channel down. The controlled device (also called the receiver) decodes the infrared pulses of light into binary code that its internal microprocessor understands. Once the signal is decoded, the microprocessor executes the commands.
IR remotes use LED lights to transmit their infrared signals. This results in a few limitations of the technology. Since light is used to transmit the signal, IR remotes require line-of-sight, which means you need an open path between the transmitter and receiver. This means that IR remotes won't work through walls or around corners. They also have a limited range of about 30 feet.
This gives RF remotes a much greater range than IR remotes. RF remotes can work at distances of 100 feet or more. This makes them useful in applications such as garage door openers and car alarms. You can also now find RF remotes being used with some modern satellite television systems.
RF remotes aren't without their own issues, however. Although range is greatly improved compared to IR remotes, interference can be an issue for RF remotes due to the large number of radio waves all around us nearly all the time. For example, wireless internet and cell phones both use radio signals.
To get around the issue of interference, many RF remotes only transmit at specific frequencies. They can also embed digital address codes in the radio signals to ensure that a receiver only responds to the correct radio signals.