It looks like a trivial gesture, but every time you press a button on Tv remote controla small technological wonder is activated. In a few fractions of second, a circuit closes, a light signal is generated and the TV receives and interprets a command. All wireless and apparently effortlessly. The mechanism behind the functioning of the remote controls is almost always based on Transmission of infrared light or Ir (from English “infrared“), An invisible form of electromagnetic radiation which, modulated precisely, transports information from one point to another. This information, coded in binary sequences (i.e. made only “0” And “1”), are interpreted by the microprocessor of the TV, or by the controlled devices in the event of a universal remote control, to perform useful actions, such as raising the volume, changing the channel or turning off the appliance. Know the Technology of infrared remote controls It can allow us to appreciate these daily devices more.
How infrared remote controls work
When you press the button of your remote control, the contact under that button closes and completes a circuit. The integrated circuit or Ic (Integrated Circuit) notes this action and generates a binary code specific for that command. This code is then sent through a Infrared ledor a small light emitter diode, located in the front of the remote control.
The infrared light is not visible to the naked eye: it is located in an area of the electromagnetic spectrum beyond red. The IR LED transmits a sequence of impulses, turning on and off at a precise rhythms. The length of the intervals between these impulses can represent, for example, one “0” or a “1”depending on the protocol used. A protocol is a set of rules and codes that define how the data must be transmitted and interpreted: one of the best known is the Sony Control-S protocolwhich uses 7 -bit codes to represent each command.
On the TV side, the IR receiver – generally placed on the front of the apparatus – it is able to detect these impulses. A integrated filter allows the receiver to ignore other sources of infrared light (such as sunlight or fluorescent lamps), focusing only on those with a wavelength of approx 980 nanometers and modulated at a specific frequency. This mechanism serves to reduce interference, which otherwise could compromise communication.
Once the impulses are received, through a decoder the receiver converts them into an electrical signal and sends it to microprocessor of the TV. If the binary code corresponds, for example, to the “Volume Su” command (coded as 001 0010 In the Sony system), the microprocessor performs the education and raises the volume. When you stop pressing the button, a command of “stop”which reports to the processor to stop the action.
Did you know? By focusing a camera (like that of your smartphone) on a infrared remote control in action you can be able to see the infrared light emitted by the latter, which will appear on the screen as white or purple.
Limits of IR remote controls
The precision of this process is such that the commands are performed almost instantly, but there are some limitations. IR remote controls require one direct line between the transmitter and the receiver: If there is an obstacle between the remote control and the TV, the signal does not arrive. Furthermore, The flow is limited to about ten meters.
