By John Holobinko, American Lightwave Systems, Inc.
In major metropolitan areas the need exists to consolidate headends and to provide a wide variety of video, data and telephony services across the CATV network. Digital Backbone Networks which connect a number of primary transport hubs together are the primary means of establishing these metropolitan networks. Other means are broadband linear (AM) supertrunks.
Questions arise as to the degree of interoperability of these networks with the standard telephony network; the need to transport BTSC compatible video, baseband and RF scrambled video, satellite delivered MPEG-2; management of local commercial insertion, preservation of revenue generating data within the video vertical blanking interval, the need to carry telephony and data traffic, and the amount of ancillary processing equipment required at each primary hub.
This paper analyzes the need for SONET compatibility in the metropolitan network, and provides an economic and technical analysis of signal quality at the subscriber, processing equipment at the various primary headends and effects on the design and cost of the AM hybrid fiber/coax. networks which are fed by the digital backbone network, based upon the technologies used.
A network design is presented which allows cost effective implementation of digital video and telephony services today, plus a graceful migration path which provides a means of network expansion fo_r accommodating higher levels of telephony and data traffic for the future.