Digital duplex transmission system

DETAILED DESCRIPTION We claim: 1.
A digital duplex transmission system comprising: two terminals interconnected by a 2-wire transmission line; first means disposed in one of said terminals coupled to said line for transmitting isochronous digital signals as pulse encoded signals of one type having a duty factor not exceeding 50% over said line; second means disposed in the other of said terminals coupled to said line for transmitting isochronous digital signals as pulse encoded signals of a different type having a duty factor not exceeding 50% over said line; said one type of encoded signals and said different type of encoded signals having the same digit repetition rate; third means disposed in said one of said terminals coupled to said line to receive said different type of encoded signals from said line; and fourth means disposed in said other of said terminals coupled to said line to receive said one type of encoded signals from said line; the timing of one of said one type of encoded signals and said different type of encoded signal transmitted from one of said one of said terminals and said other of said terminals having a predetermined fixed relationship with the other of said one type of encoded signals and said different type of encoded signals received at said one of said one of said terminals and said other of said terminals such that the periods of zero signal in said one of said one type of encoded signals and said different type of encoded signals coincide with the significant portions of said other of said one type of encoded signals and said different type of encoded signals.
2.
A system according to claim 1, wherein said one of said one of said terminals and said other of said terminals is said other of said terminals.
3.
A system according to claims 1 or 2, wherein said one type of encoded signals are dipulse encoded signals having a given format and said different type of encoded signals are dipulse encoded signals having a format different than said given format.
4.
A system according to claims 1 or 2, wherein said one type of encoded signals are dipulse encoded signals, and said different type of encoded signals are simple binary signals in an alternate mark inversion format