Enhanced line powered amplifier

• US 4,961,218 A
• Filed: 05/17/1989
• Issued: 10/02/1990
• Est. Priority Date: 05/17/1989
• Status: Expired due to Fees

• Current Assignee: Wilcom, Inc.
• Original Assignee: Tollgrade Communications Incorporated (Enghouse Systems Limited)
• Inventors: Kiko, Frederick J.
• Primary Examiner(s): NG, JIN FAY
• Assistant Examiner(s): Vaas, Randall S.
• Application Number:
  US07/352,863
• Time in Patent Office: 503 Days
• Field of Search: 379/338, 379/344, 379/340, 379/398, 379/346, 379/347, 379/406, 379/390, 379/404, 379/402, 379/345, 333/213, 340/425
• US Class Current: 379/347
• CPC Class Codes: H04B 3/44 Arrangements for feeding power to a repeater along the transmission line

Abstract

An enhanced amplifier for interconnecting a two-wire, bidirectional cable side transmission path and a two-wire bidirectional equipment side transmission path in a communication system includes a first hybrid splitter and a second hybrid splitter. The first hybrid splitter is formed of a cable-to-equipment voltage sense amplifier, a shunt current driver, and a series current compensator for generating a first simulated terminating impedance. The second splitter is formed of an equipment-to-cable voltage sense amplifier, the shunt current driver and the series current compensator for generating a second simulated terminating impedance. Other features disclosed include automatic gain adjustment circuitry for automatically setting the gain in gain/equalizer circuits to a fixed level. Further, auto-balancing circuitry is provided for adjusting automatically and continuously both equipment and cable side balance networks.

Claims

1. An enhanced amplifier for interconnecting a two-wire, bidirectional cable side transmission path and a two-wire, bidirectional equipment side transmission path in a communication system, said line powered amplifier comprising:

first hybrid splitter means coupled to receive first signals originating from the cable side transmission path and arriving at a cable side port for amplifying and transmitting said first signals to the equipment side transmission path via an equipment side port;

second hybrid splitter means coupled to receive second signals originating from the equipment side transmission path and arriving at the equipment side port for amplifying and transmitting said second signals to the cable side transmission path via the cable side port;

said first splitter means including cable-to-equipment voltage sense amplifier means, shunt current driver means, and series current compensator means, said cable-to-equipment sense amplifier means being coupled to said cable side port for generating a cable side voltage, said shunt driver means and said series current compensator means being responsive to said cable side voltages for generating a first current which is passed to said cable side transmission path to provide a first simulated terminating impedance;

said second splitter means including equipment-to-cable voltage sense amplifier means, said shunt current driver means, and said series current compensator means, said equipment-to-cable voltage sense amplifier means being coupled to said equipment side port for generating an equipment side voltage, said shunt driver means and said series current compensator means being responsive to said equipment side voltage for generating a second current which is passed to said equipment side transmission path to provide a second simulated terminating impedance;

cable-to-equipment gain/equalizer circuit means being also responsive to said cable side voltage for generating a cable-to-equipment gain control voltage, said shunt driver means and said series current compensator means being responsive to said cable-to-equipment gain control voltage for generating an amplified cable-to-equipment signal to said equipment side port;

equipment-to-cable gain/equalizer circuit means being also responsive to said equipment side voltage for generating an equipment-to-cable gain control voltage, said shunt driver means and said series current compensator means being responsive to said equipment-to-cable gain control voltage for generating an amplified equipment-to-cable signal to said cable side port; and

equipment side balance network means being also responsive to said cable side voltage for preventing said first signals originating from the cable side transmission path and sensed by said equipment-to-cable sense amplifier means from being returned to said cable side port.

2. An enhanced amplifier as claimed in claim l, further comprising cable side balance network means being also responsive to said equipment side voltage for preventing said second signals originating from the equipment side transmission path and sensed by said cable-to-equipment sense amplifier means from being returned to said equipment side port.

4. An enhanced amplifier as claimed in claim 2, further comprising auto-balancing means responsive to said cable side voltage and said equipment-to-cable gain control voltage for adjusting automatically and continuously said cable side balance network means to match impedance on said cable side transmission path. said auto-balancing means being responsive to said equipment side voltage and said cable-to-equipment gain control voltage for adjusting automatically and continuously said equipment balance network means to match impedance on said equipment side transmission path.

5. An enhanced amplifier as claimed in claim 4, wherein said auto-balancing means includes multiplexer means for switching alternately its input between said cable side port to adjust said equipment balance network means and said equipment side port to adjust said cable balance network means.

12. An enhanced amplifier as claimed in claim 4, wherein said auto-balancing means is formed of AGC amplifier means and correlation circuit means for generating a cable side correlation signal only when said equipment-to-cable gain control voltage is higher than said cable side voltage and for generating an equipment side correlation signal only when said cable-to-equipment gain control signal is higher than said equipment side voltage.

3. An enhanced amplifier as claimed in claim l, further comprising automatic gain adjustment means being responsive to a detection signal generated from the cable side transmission path and arriving at the cable side port when switch means is activated for automatically setting the gain of said cable-to-equipment gain/equalizer circuit means and said equipment-to-cable gain/equalizer circuit means.

6. An enhanced amplifier as claimed in claim l, further comprising cable-to-equipment gain correcting means coupled to said cable-to-equipment gain/equalizer circuit means and first gain switch means operatively connected to said cable-to-equipment gain correcting means for varying said cable side voltage when said first gain switch means is moved from a non-loaded cable position to a loaded cable position.

7. An enhanced amplifier as claimed in claim 6, further comprising equipment-to-cable gain correcting means coupled to said equipment-to-cable gain/equalizer circuit and second gain switch means operatively connected to said equipment-to-cable gain correcting means for varying said equipment side voltage when said second gain switch means is moved from a non-loaded cable position to a loaded cable position.

8. An enhanced amplifier as claimed in claim l, further comprising power extractor means coupled between coils in a D.C. bypass line for generating positive and negative d.c. supply voltages for said line powered amplifier.

9. An enhanced amplifier as claimed in claim l, wherein said cable-to-equipment gain/equalizer circuit means is comprised of a first transconductance amplifier whose output impedance is changed by a variable gain signal.

10. An enhanced amplifier as claimed in claim 9, wherein said equipment-to-cable gain/equalizer circuit means is comprised of a second transconductance amplifier whose output impedance is changed by said variable gain signal.

11. An enhanced amplifier as claimed in claim 10, wherein said automatic gain adjustment means is formed of a 1 KHz detector to generate the detection signal, a clock generator a counter, a AC/DC converter, a comparator and a plurality of resistors for generating said variable gain signal.