Hi,
I am currently studying computer networks and I have been reading about how data is transmitted via copper wires and fiber optics.
I understand the very basics of computers, data, logic gates and binary code.
However, currently I am struggling to wrap my head around how data can be transmitted by copper/light? It just does not make sense to me!
Can someone shed light on this?
In: Technology
You have the essence of the problem correct. We need to somehow send a signal or message out and have the other end be able to receive it.
Signal on=1
Signal off=0
Next question then is how do we get it there?
Through some sort of channel or medium is the answer of course so for us here we are talking about wires or cables.
With wires or cables we suddenly are hit with the problem of how far can we send some message down the wire before it starts to lose strength and becomes just noise. Attenuates. This would be because of the resistance of the wire or cable.
Let’s talk about how is the signal sent and received. If it’s a fibre cable, fibre optic, then the sending side will have a really fast transmitter that just sends out photons, pulses of light, that represent the bits. Usually a laser or LED will do the job here.
On the receiving side there will be a photo diode (?) that gets that pulse and turns it back into electrical pulses which then are turned into bits.
For copper it’ll be the same concept except the pulses will be whether the electrical signal is on or off.
Fibre optic is much faster because the energy you need to send photons down it is way less than having to shunt electrons and current around. Also the resistance is way less. Photons are massless so you can send a ton of them without heating up the wire. Electrons, not so much.
In both these case though you will also need to have repeaters set up along the cables to boost the signal when is weakens too much. Like for undersea cables it’s every 30kms or so?
Lastly, if we remember that no pulse or signal means bit=0 then how are we meant to know what to do if there is no traffic? No signal? Well this is where protocols come in. Communications protocols. Think of them as being able to understand wake words like “Ok Google” or “Hey Alexa” for when to start/stop expecting a signal.
[fibre optics](https://www.otelco.com/resources/a-guide-to-fiber-optic-internet/)
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