I understand that the name "Modem" stands for Modulator/Demodulator, which means that it works on the analogic singal coming from the backbone and translates it into digital.
However, I was just thinking: does the network card on the PCs work as Modems as well? I have checked and noticed that, somehow, UTP cables transfer inforation through digital signals.
How does that work? Are the digital signals the same that the CPU transmits to other componentes in the computer via circuits?
From what I see, there's 3 types of signal transfer:
- From CPU to other components via Circuits
- Something else via Ethernet Cables
- Via internet
Why we need to modulate signal to send it through the backbone and do not need to modulate it to transfer data via UTP cables?
EDIT: Got some interesting answers (thank you very much @rickybeam and @user2964971) but it still isn't clear for me why we require mod/demod for the backbone, but we don't need it to Ethernet.
I think that a better way of asking the same would be: via internet (say dial up) we convert electronic signals into waves and back, and Ethernet just get electronic signals and send it through just like in a circuit, would that be the case?