Bilateral signal transmission system

A bilateral transmission system for bilateral signal transmission through a two-wire transmission line, including a plurality of first bilateral transmission circuits and a plurality of second bilateral transmission circuits which are alternately inserted in the two-way transmission line at substantially regular intervals;

• said first bilateral transmission circuits each comprising a first amplifier for transmitting the signal in the forward direction, a first passive by-pass signal path for transmitting the signal in the reverse direction and a first pair of hybrid circuits for connecting said first amplifier and said first bypass signal path in parallel and to the two-way transmission line;
• and said second bilateral transmission circuits each comprising a second amplifier for transmitting the signal in the reverse direction, a second passive by-pass signal path for transmitting the signal in the forward direction and a second pair of hybrid circuits for connecting said second amplifier and said second by-pass signal path in parallel and to the two-way transmission line, and wherein each pair of the hybrid circuits are comprised of a transformer having a primary winding with a neutral tap and a secondary winding with a neutral tap, and a pair of balancing networks for connecting the primary and secondary windings to the two-way transmission line, wherein the primary and secondary windings jointly define said passive by-pass signal path and an amplifier is connected between the neutral taps of the primary and secondary windings for transmitting the signal.