Ternary data transmission system

Abstract

A source of a duobinary data signal is connected to a remote point by a coupling network having a high pass characteristic and transmission line. The data signal received at the remote point is subtracted from a delayed version thereof to derive the change representative signal, which is utilized at the remote point to regenerate and/or detect code violations of the data signal. Preferably, the received data signal is subtracted from a version thereof delayed by one bit time period. Circuitry generates an indication of a violation when, after assuming one extreme level in a given bit time period, the change representative signal again assumes the same level before assuming the other extreme level during a bit time period separated by an odd number of bit time periods from the given bit time period. Circuitry may also convert the change representative signal back to the duobinary data signal. Specifically, a three-state reversible binary counter is stepped up one state each time the change representative signal assumes its high level, is stepped down one state each time the change representative signal assumes its low level, and remains unchanged in state each time the change representative signal assumes its intermediate level.

Dependencies are inferred from the claim text.