Multiple station communication circuit

Claim 1

IN A COMMUNICATION CIRCUIT FOR ESTABLISHING CONFERENCE CONNECTIONS AMONG A PLURALITY OF SUBSCRIBER LINES, AT LEAST A FIRST AND SECOND COUPLING NETWORK EACH HAVING TWO TERMINAL PAIR CONNECTABLE TO TWO SUBSCRIBER LINES, A FIRST DISTINCT TRANSMISSION PATH COUPLING THE SUBSCRIBERS OF SAID FIRST NETWORK TO THE SUBSCRIBES OF SAID SECOND NETWORK, SAID FIRST TRANSMISSION PATH COMPRISNG AN AMPLIFIER HAVING A LOW INPUT IMPEDANCE AND HIGH OUTPUT IMPEDANCE, A FIRST WINDING CONNECTED ACROSS THE INPUT OF SAID FIRST TRANSMISSION PATH AMPLIFIER AND INDUCTIVELY COUPLED WITH SAID FIRST COUPLING NETWORK SUBSCRIBERS AND A SECOND WINDING CONNECTED ACROSS THE OUTPUT OF SAID FIRST TRANSMISSION PATH AMPLIFIER AND INDUCTIVELY COUPLED WITH SAID SECOND COUPLING NETWORK SUBSCRIBERS, A SECOND DISTINCT TRANSMISSION PATH COMPRISING AN AMPLIFIER SUBSTANTIALLY IDENTICAL TO THE FIRST TRANSMISSION PATH AMPLIFIER AND HAVING THIRD AND FOURTH WINDINGS CONNECTED RESPECTIVELY ACROSS THE INPUT AND OUTPUT OF SAID SECOND AMPLIFIER AND INDUCTIVELY COUPLED RESPECTIVELY TO SAID SECOND AND SAID FIRST NETWORK SUBSCRIBERS, SAID FIRST WINDING OF SAID FIRST TRANSMISSION PATH PRESENTING A LOW IMPEDANCE CONDITION TO SAID FIRST NETWORK SUBSCRIBERS AND SAID FOURTH WINDING OF SAID SECOND TRANSMISSION PATH PRESENTING A HIGH IMPEDANCE CONDITION TO SAID FIRST NETWORK SUBSCRIBERS TO ASSURE ELECTRICAL COUPLING BETWEEN SAID FIRST NETWORK SUBSCRIBERS AND ELECTRICAL ISOLATION BETWEEN SAID FIRST AND SECOND TRANSMISSION PATHS, AND SAID THIRD WINDING OF SAID SECOND TRANSMISSION PATHS PRESENTING A LOW IMPEDANCE CONDITION TO SAID SECOND NETWORK SUBSCRIBERS AND SAID SECOND WINDING OF SAID FIRST TRANSMISSION PATH PRESENTING A HIGH IMPEDANCE TO SAID SECOND NETWORK SUBSCRIBERS TO ASSURE ELECTRICAL COUPLING BETWEEN SAID SECOND NETWORK SUBSCRIBERS AND ELECTRICAL ISOLATION BETWEEN SAID FIRST AND SECOND TRANSMISSION PATHS, A PLURALITY OF NETWORKS EACH SIMULATING ONE OF SAID SUBSCRIBERS'' CIRCUITS, AND MEANS RESPONSIVE TO THE REMOVAL OF ANY OF SAID SUBSCRIBERS'' CIRCUITS FOR SUBSTITUTING A SIMULATING NETWORK THEREFOR.