Over longer distances, installers have been using boosters and UTP converter baluns, however some issues with HDCP compatibility have arisen. All these issues are solved by Active Optical. Being a short point-to-point connection, it is easy to install and does not limit the physical distance as HDMI has. AOC uses the same optical technology as your household FTTH NBN connection (or S/PDIF toslink cable). This is basically an optical core protected by a sheath, with a receiver and transmitter attached to each end. Although copper is still present in these cables, 4K video doesn’t use the majority of their bandwidth.