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
Both are very simple, but very different.
For copper wire transmission, you actually have two wires: the data wire and ground. The two together make a circuit.
Imagine you and a friend took two copper wires and stretched them across the street, then attached one end of each wire to a battery and the other to a light bulb. The person with the battery can connect and disconnect the wire, and the bulb will switch on and off. If the person with the battery connects and disconnects at a fixed rate (eg 10 seconds), the person at the other end could take a stopwatch and write down the state of the bulb every 10 seconds… voila, you’re transmitting binary. Now imagine you’re doing it a million times a second.
That’s fundamentally what our networking equipment does: one end turns the circuit on and off very very quickly, and the other measures the state by testing for an electrical signal. On or off, 1 or 0.
Fiber optic works in much the same way, but instead of sending an electrical signal over a wire, we literally shine a light down a long, flexible, internally reflective tube. Like a fiber optic christmas tree or [these lights](https://i.imgur.com/5YscgHG.png)
It works in much the same way – the sender turns a light on and off very fast, and the receiver has a light sensor that detects the presence of the light.
Wire is cheap but the electrical signal degrades and we can only send a simple on/off signal.
Optical fiber is more expensive but the signal doesn’t degrade anywhere near as easily, and we can “multiplex” signals by sending different wavelengths of light: eg we can send 3 signals via red, blue, and green light, and use a sensor tuned to those colours to receive three signals instead of one.
Latest Answers