Telephone system with a ground or wire return

A telephone system comprising:

• (a) a long line having a plurality of electrical conducting wires that are connected at one end to tip and ring leads at a central office and are connected at the other end to at least one substation, said plurality being used to conduct alternating signals and/or direct current, a first and a second wires of said plurality being a pair that is balanced to earth ground and has an approximate characteristic impedance, at least one repeater being intermediately connected in said plurality,
• (b) said central office having a first terminal for sending and receiving carrier frequencies on said first and second wires, said first terminal having an earth balanced input-output circuit, said central office having a D.C. power source and/or an audio frequency source, said ring and tip connecting to said first and second wires respectively,
• (c) said substation having a second terminal for sending and receiving carrier frequencies on a third and a fourth wires of said plurality, said third and fourth wires being a pair that is balanced to earth ground and has an approximate characteristic impedance, said third and fourth wires being connected to an earth balanced input-output circuit of said second terminal, wherein circuits use some power from said power source and/or said audio frequency source via said plurality,
• (d) said repeater amplifying carrier frequencies and/or audio frequencies, circuits of said repeater using some power from said power source and/or said audio frequency source via said plurality, a first input-output circuit of said repeater being connected to said first and second wires and being balanced to earth, a second input-output circuit of said repeater being connected to said third and fourth wires and being balanced to earth, and
• (e) a return path comprising an electrical conducting return means for returning direct current and/or audio frequency current from said repeater and/or said substation to said central office, a first line balancing means being used to balance said first and second wires to said return means at the interconnection of said central office to said plurality, a second line balancing means being used to balance said third and fourth wires to said return means at the interconnection of said substation to said plurality, a third line balancing means being used to balance said first and second wires to said return means at the interconnection of the first input-output circuit of said repeater, and a fourth line balancing means being used to balance said third and fourth wires to said return means at the interconnection of the second input-output circuit of said repeater.