Digital communication system
AssigneeInternational Standard Electric Corporation
InventorsDietrich Becker, Firoz Kaderali, Roland Liebscher
Life of this patent
Estimating the term…
Abstract
A digital subscriber terminal equipment is connected to the line circuit at a local exchange via a conventional subscriber line but permits simultaneous transmission of speech and data (e.g., viewdata). The terminal equipment and the line circuit each contain a central unit, a direction-separating unit, and a 10-bit data bus; the terminal equipment also includes a codec with a filter. The central units control the writing and reading of the digital signals into and out of the data bus and form on the subscriber line a main channel for data or speech, an additional channel for control, and an additional data channel.
Claims5
A digital communications system comprising an exchange interconnecting a plurality of subscriber terminals, said exchange including a plurality of line circuits with each line circuit being connected to a separate one of said terminals over a bidirectional digital subscriber line, each line circuit and each terminal including a central unit, each terminal including a main source of digital data and certain of said terminals including an auxiliary source of data;
- a multiplex data bus in each terminal interconnecting said central unit, said main digital data source, the auxiliary data source with said bidirectional subscriber line;
- and means in said central unit of a terminal for directing digital data from each data word received from the line to said main source of digital data within the terminal for directing further data from each word to the auxiliary source within the terminal and for utilizing still further digital data from each word for signalling and for synchronizing said data bus.
Dependencies are inferred from the claim text.