Local digital telephone system on two-way cable television

Abstract

Abstract A telephone transmission system using several 6 MHz video bands and return channels in a cable TV distribution line is proposed. In this system, cable TV is used for subscriber accomodation with a local telephone system. In order to realize high accomodation capability in a conventional tree-shaped CATV network, we adopt a two-level structure for the voice distribution, and use a distinct media access protocol for each level: the logical loop scheme for the higher, and the polling-selecting scheme for the lower. The design concept of this system has compatibility with any existing CATV installations, and can be flexibly applied to them. Based on the analysis of the accomodation capacity of the above two media access protocols, a CATV local telephone network for a medium-scale local switch is designed. This system is expected to give one of the most economical subscriber distribution capabilities with integrated telephone and video service.