As cable systems seek to add telephony services and interconnect headends for operational efficiencies, they will migrate toward use of digital fiber optics for the interconnections.
This is true even of systems which expect to continue to deliver analog programming to the home for the immediate future. When developing a digital optical interconnection system, one may choose either proprietary systems, or may select compatible standard systems available from a number of manufacturers. Here-in the case is made for the latter approach, in which standard systems, originally developed for telephony applications, are used to transport video and ancillary signals from one headend location to another.
Interface issues include not only video, but also audio services, addressable data, control and new data services. The versatility of the network is enhanced by integrating cable television's needs with standard multiplexing systems. Multiplexing is explained, and the hierarchies in common usage are introduced.
Finally, a short space is devoted to describing some of the quality issues in hybrid analog/digital networks.