One cable is enough
When we talk about a “single-cable solution”, we actually mean it. There is no second cable for power supply. The only cable that is needed is a special coaxial cable that conducts all currents and signals required for control, power supply and signal transmission to the top unit. As such, vehicle installation requires only minimal intervention. A single pass-through is enough.
For the TWIN option, a second coaxial cable is used.