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IR Remote Controls and Binary Codes

IR Remote Controls and Binary Codes

In this post I'll be trying to simplify how remote controls operate. I'm not exactly the best teacher but I am interested and fascinated by this technology and the physics of it in general. Please bare with me here, I'll give it my best shot.

Infrared (IR) Remote Controls create invisible infrared light signals by generating heat. This heat is generated by electromagnetism. What is electromagnetism you may ask? According to Merriam-Webster's Word Central Dictionary for Kids electromagnetism is: "a natural force arising from interactions between charged particles." The particles artificially get their charge from the batteries in the remote control to generate this electrical heat.

Infrared light is within the visible part of the infrared spectrum. Although your naked eye cannot see the IR signal being transmitting by the remote control, it can be seen by a camera. This signal is more specifically considered near-infrared. This info is pulled from Mehta, Akul. "Introduction to the Electromagnetic Spectrum and Spectroscopy". Retrieved 2011-11-08.

When you press a button on a remote control a circuit is completed. The underside of each rubber button has an electrical conductor on it. 

Conductor under the Rubber Buttons

When you press the button, the conductor on the underside of the button completes the electrical circuit on the circuit board.

Connection where rubber conductor completes the circuit on the Circuit Board

This results in a series of binary codes being transmitted via infrared light pulses through the LED (light emitting diode) on the transmitting end of the remote. 

Remote Control LED

I think this phenomenon is a little like Morse code. Most people are at least familiar with Morse code if you've watched any old military movies. The remote control sends this series of binary codes via the IR signals to the receiver (your TV, DVD Player, VCR, Cable Box, DVR, Stereo, Air Conditioner, etc) It's kind of like sending your device a bit of visual Morse code. Your receiver has binary code translation built into it's own circuit board.

The infrared wavelength is invisible to the naked eye. According to the Lamp Section, National Electrical Manufacturers Association (1998), the signal sent is usually between 930–950 nm to prevent interference of UV light. 

An individual binary code is made up of a series of bits. Each bit has a numeric value of "0" or "1" where 0 = off and 1 = on. Every button on your remote has its own unique binary code when pressed. This means each button sends its own unique series of light pulses to the transmitter. This is how your device knows what you are trying to tell it to do (ie "power on" or "volume up").

Binary codes can be translated by converting them to decimal form and then to text through the ASCII Chart. This seems complicated but is probably not all that bad if you sit down and take the time to learn it. Otherwise there are binary code translation tools available such as the ASCII Chart I mentioned above. I'll take the easy road and leave the real translating to the professionals!

This is a pretty rudimentary guide and if any real physics teachers or binary code experts read this, I probably missed some things. I apologize in advance. This is how I understand it. Thank you for reading!

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