Range extender with gain

Claim 2

A range extender with gain used to provide selective amplification to signals applied to a relatively long subscriber loop comprising: a through-transmission path coupled to said subscriber loop; a voice amplification path coupled to said subscriber loop; a loop current detector coupled to said subscriber loop; means for delivering to said detector a dc voltage corresponding to the dc current on the subscriber loop; means for supplying a bias potential to said detector; and control means for selectively applying telephone signals to either of said paths in response to the loop current detector, CHARACTERIZED IN THAT the range extender further comprises means responsive to common-mode time-varying currents on the subscriber loop for varying the bias potential supplied to the loop current detector thereby rendering said loop current detector insensitive to said common-mode time-varying currents.

Claim 3

A range extender according to claim 1 wherein the control means comprise a pulse reshaper circuit optically coupled to the variably biased loop current detector for further isolating said detector from the range extender ground potential.

Claim 4

A range extender according to claim 2 wherein the control means further comprise a logic circuit having a first input terminal coupled to the pulse reshaper circuit output terminal, a second input terminal optically coupled to an automatic number identification (ANI) tip party test signal, and a third input terminal coupled to a contact of a path selection relay.

Claim 5

A range extender according to claim 3 wherein said logic circuit is a four state asynchronous logic circuit designed to prevent the range extender from remaining in an unrecoverable ANI testing state.

Claim 6

A range extender according to claim 2 wherein said pulse reshaper circuit comprises three logic NAND gates and two feedback couplings for regenerating minimum make and minimum break dial pulse periods.

Claim 7

A range extender with gain used to provide selective amplification to signals applied to a relatively long subscriber loop comprising: a through-transmission path coupled to said subscriber loop; a voice amplification path coupled to said subscribed loop; a loop current detector comprising an amplifier having an output terminal and means for delivering to said amplifier a dc voltage corresponding to the dc current on the subscriber loop; means for supplying a bias potential to said loop current detector; and relay control means for selectively applying telephone signals to either of said paths in response to the loop current detector, CHARACTERIZED IN THAT the loop current detector further comprises: a pair of threshold detectors each having an input terminal coupled to the amplifier output terminal and each having an output terminal; a logic gate coupled to said threshold detectors' output terminals; a photocoupler for generating an optical signal in response to the gate output signal; and means responsive to common-mode time-varying currents on the subscriber loop for varying the bias potentials supplied to said amplifier, threshold detectors, gate and photocoupler thereby rendering the loop current detector insensitive to said common-mode time-varying currents.

Claim 8

A range extender with gain used to provide selective amplification to signals applied to a relatively long subscriber loop comprising: a through-transmission path coupled to said subscriber loop; a voice amplification path coupled to said subscribed loop; a loop current detector comprising an amplifier having an output terminal and means for delivering to said amplifier a dc voltage corresponding to the dc current on the subscriber loop; means for supplying a bias potential to said loop current detector; and relay control means for selectively applying telephone signals to either of said paths in response to the loop current detector, CHARACTERIZED IN THAT the loop current detector further comprises: a pair of threshold detectors each having an input terminal coupled to the amplifier output terminal and each having an output terminal; a logic gate coupled to said threshold detectors' output terminals; a photocoupler for generating an optical signal in response to the gate output signal; and means responsive to common-mode time-varying currents on the subscriber loop for varying the bias potentials supplied to said amplifier, threshold detectors, gate and photocoupler thereby rendering the loop current detector insensitive to said common-mode time-varying currents.

Claim 9

A range extender according to claim 6 wherein said generating optical signal is coupled to the relay control means for selectively establishing a loop connection through said voice amplification path or said through-transmission path.

Claim 10

A range extender according to claim 7 wherein said relay control means comprise a pulse reshaper circuit coupled to said optical signal for regenerating dial pulse periods.

Claim 11

A range extender according to claim 8 wherein said pulse reshaper circuit comprises first, second and third logic NAND gates, and first and second feedback paths coupling the output terminal of the third gate to the input terminals of the first and second gates for respectively regenerating minimum make and minimum break dial pulse periods.

Claim 12

A range extender according to claim 8 wherein the relay control means further comprise a four-state asynchronous logic circuit having a first input terminal coupled to the pulse reshaper circuit output terminal, a second input terminal optically coupled to an automatic number identification (ANI) tip party test signal, and a third input terminal coupled to a contact of a selective path relay.