Everyone has used a remote. For changing channels on a TV, for controlling DVD players, as video game controllers, or even for unlocking your car remotely. But how are these devices able to wirelessly transmit data to another device? In what format is data sent? Using what medium?
How data is shared
Before seeing how it is wirelessly done, we need to understand how it is transferred even with wires. How do we convert electrical pulses into meaningful data that we can use?
Machines work in only
1s. They operate using only two outcomes, something is there, and nothing is there. This is easy to program into any signal. We can have two values, and set one as 0 and another as 1. The software then does the interpretation to code.
So data is sent with always two outcomes. Now we can see how we can send that without wires.
How it is wirelessly done
Most remotes use IR light to do wireless operations. IR light is light that is in a spectrum that we humans can not see (try pressing buttons on your remote and looking at it through a phone’s camera. You will see nothing but the camera will have interesting effects!). Infrared light is used commonly for many wireless operations, including your remotes. The specific way they code binary values will change, but the basic concept will be the same always.
We have one specific value, say 40KHz, which will be interpreted as “1”. Not sending any data will be counted as “0”. We can design a Morse code kind structure with this, in which, if 40KHz is emitted, it is counted as “1”, and if nothing is there for a fixed length of time, we can count it as “0”.
We can now, after it has been sent in this fashion, interpret it as anything we want, say a command “change the channel”. There are other methods too, that I won’t go too deep into, like “Pulse Distance Coding”, in which the distance between the pulses determines the value. But the point is – no matter what format is used – it is coded as binary values. These are the easiest to understand by the machines.