This standard defines the characteristics and normative specifications for the digital network interface between a cable television system and commercially available digital cable products that are used to access multi-channel television programming. The network interface is also compatible with existing analog and digital set-top terminal equipment owned by cable operators and with terminal equipment developed via the OpenCable™ specification process. All specifications in this document apply at the Demarcation Point except as specifically noted. Specifications noted to apply at the terminal device are applicable regardless of whether that device is owned by the subscriber or the cable operator. The key functional characteristics assumed in this document are the following:
- The cable network provides services utilizing 6-MHz in-band channel(s), out-of-band forward data channel(s), and out-of-band reverse data channel(s). The 6-MHz in-band channels follow the CEA-542-C channel-tuning plan. However, the frequency location can change over time such that analog and digital channels could be located anywhere in the downstream operating range. Nothing in this standard precludes the use of other narrowband or wideband digital signals.
- The 6 MHz in-band channels are used to transport digital services (QAM modulated MPEG-2 transport streams) as well as analog services (NTSC AM-VSB channels). Nothing in this standard precludes the use of other modulation modes.
- Services are either in the clear or protected using conditional access technology.