EP0160411A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Line feed circuit for a digital signal loop
Assignee: Nortel Networks Ltd
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Filing: 1985-04-02
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Granted: —
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Expires: 2005-04-02
Abstract
Abstract 57 A line feed circuit for a digital signal loop includes an alternating current coupling circuit with tip and ring transformer windings (18, 15) being joined by a capcitor (19) for transmitting bipolar AMI time compression multiplex (TCM) signals between a telephone network and a telephone line (100). The line feed circuit also includes a direct current coupling circuit having a current limiting circuit (21, 22) being connected in series with one of the tip and ring windings and a power terminal (13)- In operation direct energizing current for supplying a remote terminal apparatus or station set with energizing current is available up to a predetermined limit with the advantage that power dissipation in the line feed circuit is minimized.
Inventors
- 👤 Joseph William Hingston
- 👤 Stephen Thomas Urbach
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 09:10
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/08; H04M19/001; H04Q; H04Q2213/00; H04Q2213/1308; H04Q2213/13082; H04Q2213/13166; H04Q2213/13302
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
202 words
A line feed circuit for supplying energizing direct current for operation of a remote terminal apparatus being connected by way of a two-wire communication line (100), and for coupling digital signals between the communication line and an associated communication facility, comprising: power and ground terminals (13, 14) for connection to a power source; tip and ring terminals (12, 11) for connection to the communication line; an alternating current coupling circuit including a capacitor (19) and a transformer (18), the transformer having a primary winding (17) and tip and ring windings (16, 15), the tip and ring windings being connected in series with each of the tip and ring terminals respectively, and the capacitor being connected between the tip and ring windings, via junctions (15a, 16a); a direct current coupling circuit including a current limiting circuit (21, 22) being connected in series between the power terminal and one of the junctions of the capacitor and one of the tip and ring windings, the other junction of the capacitor and the other of the tip and ring windings being connected to the ground terminal, whereby in operation direct energizing current up to a predetermined limit is available for operation of the remote terminal apparatus.
Claim 2
Dependent Claim
202 words
A line feed circuit for supplying energizing direct current for operation of a remote terminal apparatus being connected by way of a two-wire communication line (100), and for coupling digital signals between the communication line and an associated communication facility, comprising: power and ground terminals (13, 14) for connection to a power source; tip and ring terminals (12, 11) for connection to the communication line; an alternating current coupling circuit including a capacitor (19) and a transformer (18), the transformer having a primary winding (17) and tip and ring windings (16, 15), the tip and ring windings being connected in series with each of the tip and ring terminals respectively, and the capacitor being connected between the tip and ring windings, via junctions (15a, 16a); a direct current coupling circuit including a current limiting circuit (21, 22) being connected in series between the power terminal and one of the junctions of the capacitor and one of the tip and ring windings, the other junction of the capacitor and the other of the tip and ring windings being connected to the ground terminal, whereby in operation direct energizing current up to a predetermined limit is available for operation of the remote terminal apparatus.
Claim 3
Dependent Claim
76 words
A line feed circuit as defined in claim 1 wherein the current limiting circuit comprises: a feed resistor (21) and a voltage regulator (22), the voltage regulator having an input port (23), an output port (24), and a control port (25), and being connected via the input and control ports between the power terminal and said one Junction, the feed resistor being connected in series between the control and output ports, for conducting the energizing current.
Claim 4
Dependent Claim
57 words
A line feed circuit as defined in claim 1 wherein the one junction is defined by the connection of the capacitor and an end of the ring winding remote from the ring terminal, and the other junction is defined by the connection of the capacitor and an end of the tip winding remote from the tip terminal.
Claim 5
Dependent Claim
76 words
A line feed circuit as defined in claim 3 wherein the current limiting circuit comprises: a feed resistor (21) and a voltage regulator (22), the voltage regulator having an input port (23), an output port (24), and a control port (25), and being connected via the Input and control ports between the power terminal and said one junction, the feed resistor being connected in series between the control and output ports, for conducting the energizing current.
Claim 6
Dependent Claim
131 words
A line feed circuit as defined in claim 3 wherein the power terminal is for connection to a negative voltage terminal (-V) of the power source and wherein the current limiting circuit comprises: a feed resistor (21) and a voltage regulator (22), the voltage regulator having an input port (23) being connected to said one junction, a control port (25) being connected to the power terminal and an output port (24) being connected in series with the feed resistor to the power terminal the voltage regulator being operable in a linear mode to restrict a flow of the energizing current through the feed resistor at the predetermined limit, and otherwise being operable in a saturation mode whereby the flow of energizing current at less than the predetermined limit is substantially unrestricted.
Claim 7
Independent Claim
144 words
A method for supplying energizing current from a central power source in an associated communications facility to a power supply (130) in a digital signal terminal being located remote from the communications facility and being connected thereto by way of a two-wire communication line (100), comprising the steps of: a) providing a current path between the central power source and the communication line; b) operating the current path in an unrestricted mode to supply an energizing current flow to the communication line while the energizing current flow is of less than a predetermined limit; c) operating the current path in a restricted mode to supply the energizing current flow to the communication line while the energizing current flow corresponds to the predetermined limit; whereby in step (b) energy dissipation in the current path is minimized and in step (c) excess current flow is restrained.
Claim 8
Independent Claim
144 words
A method for supplying energizing current from a central power source in an associated communications facility to a power supply (130) in a digital signal terminal being located remote from the communications facility and being connected thereto by way of a two-wire communication line (100), comprising the steps of: a) providing a current path between the central power source and the communication line; b) operating the current path in an unrestricted mode to supply an energizing current flow to the communication line while the energizing current flow is of less than a predetermined limit; c) operating the current path in a restricted mode to supply the energizing current flow to the communication line while the energizing current flow corresponds to the predetermined limit; whereby in step (b) energy dissipation in the current path is minimized and in step (c) excess current flow is restrained.
Claim 9
Dependent Claim
60 words
A method as defined in claim 6 wherein the current path is provided by a feed resistor (21) and a semiconductor device (22) arranged in a series combination and wherein in step (c) operation occurs in the semiconductor device in response to a voltage drop across the feed resistor which corresponds to the current flow being of the predetermined limit.
References Cited (Backward Citations)
No citation records indexed.
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