Patent EP0042976A1 successfully refreshed from Google Patents.
EP0042976A1
Expired / Lapsed
EP
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Bi-directional communication system for a two wire digital telephone link
Assignee: International Business Machines Corp
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Filing: 1981-05-25
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Granted: —
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Expires: 2001-05-25
Abstract
Abstract Bi-directional communications system in which a first polarity of pulses is utilized for communication of traffic in one direction, traffic in the return direction utilizing pulses of the opposite polarity. Each end of the communication link has both a sender (4) and a receiver (5). One sender (4) arbitrarily transmits only positive pulses and the receiver (5) at this end of the system recognizes only negative pulses. The inverse set of conditions is enforced at the opposite end of the link. Means are included for synchronizing the application of pulses to the link at the other end in response to the receipt of pulses at that end to avoid overlap of receive pulses at the originating end of the line.
Inventors
- 👤 Paul Abramson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 17:09
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/04; H04L; H04L5/00; H04L5/14; H04L5/1469; H04L5/1476; H04J; H04J3/00; H04J3/02; H04J3/06; H04J3/0635; H04J3/0638; H04L7/00; H04L7/02; H04L7/033; H04L7/04; H04L7/041; H04L7/044
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
199 words
- Bi-directional communications system for simultaneous communication over a two-wire link comprising: at least a first station and a second station, said stations each comprising a transmitter and a receiver connected to said two-wire link; said transmitter at said first station being capable of producing pulses of a first polarity for application to said link; said receiver at said first station being responsive to pulses of the opposite polarity to those transmitted by said transmitter at said first station; said system being characterized by: said second station having a receiver responsive to pulses of the polarity transmitted by said transmitter at said first station and having a transmitter for producing pulses of the opposite polarity thereto for application to said link; said transmitters at said first and second stations being synchronized with respect to the receipt of pulses of the polarity to which the respective receivers are responsive for applying outgoing pulses to said link at a position within the bit time defined by a given transmission rate such that said pulses when delayed by the propagation delay of said link will not arrive coincident with the generation of the pulses at the opposite ends of the said link.
Claim 2
Dependent Claim
199 words
- Bi-directional communications system for simultaneous communication over a two-wire link comprising: at least a first station and a second station, said stations each comprising a transmitter and a receiver connected to said two-wire link; said transmitter at said first station being capable of producing pulses of a first polarity for application to said link; said receiver at said first station being responsive to pulses of the opposite polarity to those transmitted by said transmitter at said first station; said system being characterized by: said second station having a receiver responsive to pulses of the polarity transmitted by said transmitter at said first station and having a transmitter for producing pulses of the opposite polarity thereto for application to said link; said transmitters at said first and second stations being synchronized with respect to the receipt of pulses of the polarity to which the respective receivers are responsive for applying outgoing pulses to said link at a position within the bit time defined by a given transmission rate such that said pulses when delayed by the propagation delay of said link will not arrive coincident with the generation of the pulses at the opposite ends of the said link.
Claim 3
Dependent Claim
178 words
- System according to claim 1, in which: said first station includes a transformer having its primary winding connected to the transmitter of said first station and its secondary winding connected to a polarity responsive current switch for passing pulses of said polarity from said transmitter to said link; a transformer having its secondary winding connected to the receiver of said first station and its primary winding connect to an opposite polarity responsive current switch for passing pulses of the opposite polarity of those-transmitted by said transmitter from said link to said receiver; said second station includes a transformer having its secondary winding connected to the receiver of said second station, and its primary winding connected to a polarity responsive current switch for passing pulses of said polarity from said link to said receiver; a transformer having its primary winding,connected to the transmitter of said second station and its secondary winding connected to an opposite polarity responsive current switch for passing pulses of the opposite polarity of those received by said receiver, from said transmitter to said link.
Claim 4
Dependent Claim
26 words
- System according to claim 2 in which said polarity responsive current switches are transistors PNP and said opposite polarity responsive current switches are transistors NPN.
Claim 5
Dependent Claim
44 words
- System according to any one of claims 1, 2 or 3 in which each said receiver comprises a phase locked loop circuit for deriving a reference frequency from the frequency of the incoming pulses of said polarity to which said receiver is sensitive.
Claim 6
Dependent Claim
52 words
- System according to any one of claims 1 to 4, further comprising: a plurality of said second stations, each being connected by a separate two-wire link to said first station and communicating thereto by means of pulses of like polarity and receiving therefrom communications via pulses of the opposite polarity thereto.
Claim 7
Dependent Claim
152 words
- Method of communicatiing bi-directionally and simultaneously over a two-wire communications link, comprising steps of: transmitting from a first station a unipolar pulse code at a bit rate established for said system and applying said code to said communications link; receiving said unipolar pulse coded signals at a receiving station connected to said two-wire link; deriving from said received unipolar pulse code the characteristic bit rate inherent in said transmission and responsive thereto, generating any response or communication to said communication line by a pulse coded unipolar signal of opposite polarity to those received; said opposite polarity unipolar pulse code pulses being applied to said communication link at a time responsive to the basic communication frequency derived from the incoming transmissions which, taking into account the inherent propagation delay of said communication link, will not interfere with or coincide in time with the original transmissions at the opposite end of said link.
Claim 8
Dependent Claim
152 words
- Method of communicatiing bi-directionally and simultaneously over a two-wire communications link, comprising steps of: transmitting from a first station a unipolar pulse code at a bit rate established for said system and applying said code to said communications link; receiving said unipolar pulse coded signals at a receiving station connected to said two-wire link; deriving from said received unipolar pulse code the characteristic bit rate inherent in said transmission and responsive thereto, generating any response or communication to said communication line by a pulse coded unipolar signal of opposite polarity to those received; said opposite polarity unipolar pulse code pulses being applied to said communication link at a time responsive to the basic communication frequency derived from the incoming transmissions which, taking into account the inherent propagation delay of said communication link, will not interfere with or coincide in time with the original transmissions at the opposite end of said link.
Claim 9
Dependent Claim
69 words
- A method as described in claim 5 further comprising: receiving said pulses of opposite polarity from said communication link; passing said opposite polarity pulses through a polarity responsive switch means connected in series with the secondary winding of a inductive means; and inversely connecting the primary as an output from said inductive means between ground and the detecting means for the reconstruction of pulses of a first polarity.
References Cited (Backward Citations)
US3339022A
Cited
GB1401436A
Cited
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