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US 4,064,377 AGranted
Electronic hybrid and hybrid repeater
AssigneeWescom Switching, Inc.
InventorJohn F. Regan
Life of this patent
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AssigneeWescom Switching, Inc.
InventorJohn F. Regan
Estimating the term…
An electronic hybrid for coupling signals between two wire and four wire transmission circuits, and capable of meeting the operating requirements of practical telephone systems. The hybrid includes a pair of terminating impedances serially connected between the two wire port and the circuitry driving that port, the impedances being precisely matched and coupled to a.c. ground, thereby providing a hybrid with excellent longitudinal balance. Amplifiers driving the two wire port through the terminating impedance may be biased to couple a d.c. potential to the two wire line whereby the terminating impedances serve as battery feed resistors. Reverse signal recovery is provided by an amplifier differentially connected to the two wire port, achieving excellent longitudinal rejection and further allowing the amplifier to serve a supervisory function. Two of such hybrids, connected back to back, with amplification interposed therebetween, form an improved transformerless repeater. In this embodiment, the amplifier may be constructed to be of variable gain, with the gain automatically adjusted as a function of sensed loop current, whereby the repeater may be installed without manually adjusting the amplification to suit the loop length.
In an electronic hybrid having a two wire port for coupling to a two wire line and separate transmit and receive ports for coupling to a four wire line the improvement comprising, driving means responsive to signals imposed on the receive port for driving the two wire line, a pair of matched resistive impedances serially connected between the driving means and the two wire port so that an impedance is in series between the driving means and each line connected to said two wire port, said driving means including means for providing an a.c. ground at the junctions joining said driving means to the respective impedances, said driving means including means for offsetting the quiescent output voltage applied to the respective lines of said two wire line, whereby said driving means provides d.c. current for said two wire line.
An electronic hybrid having a two wire port for coupling to a two wire line and separate transmit and receive ports for coupling to a four wire line comprising, driving means having an input responsive to signals imposed on said receive port for driving said two wire line, first amplifier means having an input coupled to said two wire port for driving said transmit port in response to signals received from said two wire line, cancellation means for coupling signals from said receive port to said first amplifier means to prevent said first amplifier means from responding to signals coupled to said two wire line by said driving means, first and second terminating impedances, said impedances being resistors interposed between the respective lines connected to said two wire port and said driving means, said driving means including means for producing a.c. ground at the junctions joining said driving means to the respective impedances, said first and second impedances being substantially of equal value so that said hybrid provides a terminating impedance for said two wire line balanced to ground, said driving means including means for offsetting the quiescent output voltages applied to the respective lines of said two wire line, whereby said driving means provides d.c. current for said two wire line.
An electronic hybrid for coupling a two wire line to a four wire line, said hybrid having a two wire port coupled to said two wire line, a transmit port and a receive port coupled to said four wire line and comprising first amplifier means having an input coupled to said receive port and an output driving said two wire port, second amplifier means having an input differentially coupled to said two wire port and an output, and third amplifier means having an output driving said transmit port, the output of said second amplifier means being connected to the input of said third amplifier means thereby to couple signals received on said two wire port to said transmit port, means coupling signals imposed on said receive port to said third amplifier means for cancelling signals imposed on said two wire line by said first amplifier means from the output of said third amplifier means, and a pair of matched terminating impedances connected between the output of said first amplifier means and the respective lines coupled to said two wire port, said terminating impedances being matched resistors, said first amplifier means including means providing a.c. ground at the respective junction between the first amplifier means and the terminating impedances so that the impedance looking into said two wire port is the series sum of said matched terminating impedances balanced to ground, said first amplifier means including means for offsetting the quiescent output voltages applied to the respective lines of said two wire line, whereby said first amplifier means provides d.c. current for said two wire line through said terminating impedances.
An electronic hybrid having a two wire port for connection to a two wire line and a transmit and receive port for connection to a four wire circuit comprising first amplifier means responsive to signals imposed on said receive port for driving said two wire line, second amplifier means responsive to signals imposed on said two wire port for driving said transmit port, and cancellation means for coupling signals from said receiver port to said second amplifier means to prevent said second amplifier means from responding to signals coupled to said two wire port by said first amplifier means, first and second terminating impedances interposed between the output of said first amplifier means and the respective terminals of said two wire port, said first amplifier means including feedback means for providing an a.c. ground at the output thereof for said terminating impedances, said terminating impedances being resistors of substantially equal value thereby to provide longitudinal balance to said hybrid, said first amplifier means including means for offsetting the quiescent output voltages applied to the respective lines of said two wire line, whereby said first amplifier means provides d.c. current for said two wire line through said terminating impedances.
A hybrid repeater interposable in a two wire line for providing bidirectional amplification thereto comprising, first and second electronic hybrids each having:
The hybrid repeater as set forth in claim 43 wherein the amplifier means of said one hybrid has a differential input, balanced network means for connecting said differential input across the two wire port of said one hybrid, said balanced network means being resistive so that said amplifier means senses changes in d.c. current flow in the two wire line.
In an electronic hybrid having a two wire port for coupling to a two wire line and separate transmit and receive ports for coupling to a four wire line the improvement comprising, driving means responsive to signals imposed on the receive port for driving the two wire line, a pair of matched impedances serially connected between the driving means and the two wire port so that an impedance is in series between the driving means and each line connected to said two wire port, the matched impedances being matched resistors, said driving means being biased to supply d.c. current to the two wire line through the matched impedances, said driving means including at least one operational amplifier having feedback means for producing an a.c. ground at the output thereof.
An electronic hybrid having a two wire port for coupling to a two wire line and separate transmit and receive ports for coupling to a four wire line comprising, driving means having an input responsive to signals imposed on said receive port for driving said two wire line, first amplifier means having an input coupled to said two wire port for driving said transmit port in response to signals received from said two wire line, cancellation means coupled between said receive port and said first amplifier means for preventing said first amplifier means from responding to signals coupled to said two wire line by said driving means, first and second impedances, said impedances being interposed between the respective lines connected to said two wire port and said driving means, said first and second impedances being matched resistors substantially of equal value, said driving means including means for offsetting the quiescent output voltages applied to the respective lines of said two wire line whereby said hybrid provides d.c. current to the two wire line through the matched impedances.
Dependencies are inferred from the claim text.