sending data and power on just 2 wires

[casdsys]

Does anyone know how ( serial ) data and power can be sent on just 2 wires, were talking about DC voltage. If anyone can point me in the right direction that would be great, thank you.

[I_Daniel]

I can only point not really help.

Consider a satellite dish and decoder. DC voltage is provided via the antenna socket of the decoder to the receiver on the dish. The RF signal, with it's digital encoding. is also sent along the same co-ax (Two wires ie. 1. The core. 2. The braiding surrounding the core.)

I must assume that the RF or digital signal is taken off the DC supply via a small capacitor. The braiding of the co-axial cable would normally be the common earth ( vcc -) connection.