Range extender with gain

• US 4,054,941 A
• Filed: 12/22/1976
• Issued: 10/18/1977
• Est. Priority Date: 12/22/1976
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Shichman, Harold
• Primary Examiner(s): Robinson, Thomas A.
• Assistant Examiner(s): Myers, Randall P.
• Application Number:
  US05/752,900
• Time in Patent Office: 300 Days
• Field of Search: 179/16 EA, 179/16 F, 179/17 OR
• US Class Current: 379/400
• CPC Class Codes: H04M 19/006 Circuits for increasing the range of current supply source

Abstract

An improved Range Extender with Gain (REG) comprises a floating loop current detector, a new dial pulse reshaper and a new control logic circuit. The loop current detector is powered by means of a floating power supply which renders the detector insensitive to spurious common-mode subscriber loop currents. The dial pulse reshaper comprises logic gates with two feedback paths for regenerating minimum make and break periods. The control logic circuit for controlling the relays in the REG is an asynchronous logic circuit particularly designed to avoid conventional differentiation circuits and timing problems associated with Automatic Number Identification.

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.