Eli5: how can a single data cable supply so many homes with different data at once, like for internet connections? Isn’t everything basically just 0s and 1s? If that’s the case how is it being organized and sent to the right place?

Question

Thanks for the answers! My biggest takeaway is about how bits work using different frequencies, and how fiber optics can use different colors to help organize data

In: Technology

Answer 1

For copper based internet like with cable TV, and to a certain amount it’s also true for DSL, the signal is much more complex than just 0s and 1s. Along with being encoded on many frequencies allowing for many different data-carrying channels, just like how radio has many frequencies, each signal isn’t just a single bit. Though you transmit at a fairly high rate, each thing you transmit represents many bits, requiring a bit of processing to get the binary data back.

The analogy is that you can transmit a low, medium-low, medium-high and high signal as representing the binary codes 00, 01, 10 and 11 respectively, and get double the data throughput. If you can easily discriminate between even more ranges of low/medium/high signals, you can transmit even more bits at once. However the actual signal encoding on cable is more complex than that and capable of transmitting 4, 8 or even 12 bits at once making the speeds very good on each frequency.

This does make cable internet vulnerable to signal interference as it becomes harder to tell the difference between adjacent signal levels in the face of a bit of static on the line, but coaxial cable in general tends to be well shielded, and the fact that it has to be screwed down onto the modem or TV receiver is part of that shielding. Try to screw it down about as tight as your fingers will allow, even if that means you need a small wrench to remove it later.

As for aiming the signal to the right home, often you don’t. DSL modems are on a private pair of wires for each home, but cable is shared along the local neighbourhood, being split from hardware not all that different from a cable splitter you can buy at an electronics store. Cable modems are designed to be more controlled by the internet provider than the home user – at least the types with only 1 data port – and is intentionally ignoring any data not intended for itself, only relaying data that belongs to you.