This question will be a simplification as I lack the proper knowledge.
Lets suppose we want to send a signal over the network. We will use this scheme as this is hopefully how the signals are send over the network:
Providing the above is 'roughly' how a signal transmission works, how would a circuit scheme look like for an Ethernet 100TX network cable? (the cable uses wires 1,2,3 and 6 to transfer data, 1,2 pair for Tx (transmission) and 3,6 for Rx (receive).
By asking this question I want to understand, whether both Tx wires (1,2 wires) are used to transfer data simultaneously or maybe, I always have to have two wires to actually transfer a signal over a network. If the former is true, why do I always need two cables?
Ok, the "ground wire" concept. After reading your comment for the first time, I've thought that you measure the voltage between wire1 and wire1 (made no sense) or between wire1-wire2 (you can measure only one time, so how come 2 signals). After reading the comment for the second time, I realized there can be 'a third' cable in the system. And both PC1 and PC2 can have their own 'ground cables'. The drawing:
- PC2 has its own 'ground' cable
- PC1 and PC2 cables are separate (not connected)
- on the picture, I'm sending 1111111... on the first wire and 0000000... on the second wire simultaneously. Also, notice that the time is passing by and there is no 'clock' signal in the circuit. The clock signal that tells, when one signal ends and where another signal begins. For how the clock signal looks like, see this.