Russell J Apfel

US Patent:

6351528, Feb 26, 2002

Filed:

Aug 2, 1999

Appl. No.:

09/365538

Inventors:

Russell J. Apfel - Austin TX

Assignee:

Advanced Micro Devices, Inc. - Austin TX

International Classification:

H04M 1100

US Classification:

379377, 379382, 379398, 37941301

Abstract:

The invention provides an apparatus for use with a subscriber line interface circuit in a telephone system, the subscriber line interface circuit being interposed between a telephone central office and a subscriber line, the subscriber line being coupled with a subscriber telephone device. The apparatus comprises an interface circuit for coupling the apparatus with the subscriber line; a ringing generator coupled with the interface circuit for providing a time varying signal to the subscriber line in response to a received ring signal; a detector circuit coupled with the interface circuit for detecting an impedance of the subscriber line in the presence of the time varying signal and providing a detect indication when the impedance is below a predetermined impedance threshold; and a control circuit coupled with the ringing generator and with the detector circuit for providing the ring signal to the ringing generator and receiving the detect indication from the detector circuit, the control circuit interrupting the ring signal in response to receiving the detect indication. The apparatus provides balanced ringing signals to the subscriber telephone device and detects loop AC impedance to provide ring trip detection.

US Patent:

6356624, Mar 12, 2002

Filed:

Aug 4, 1998

Appl. No.:

09/128579

Inventors:

Russell J. Apfel - Austin TX
Richard B. Webb - Austin TX
Walter S. Schopfer - Austin TX

Assignee:

Leserity, Inc. - Austin TX

International Classification:

H04M 322

US Classification:

379 2701, 379 2705, 379 2708, 37939901

Abstract:

A sensor capable of being coupled to a transmission line and monitoring a foreign voltage on the transmission line includes a voltage monitoring circuit. The voltage monitoring circuit is adapted to operate in a foreign voltage detection mode in response to receiving a first logic signal and a foreign voltage measurement mode in response to receiving a second logic signal. A method for operating a circuit to detect and measure a foreign voltage on a transmission line includes providing a first logic signal to configure the circuit to detect the foreign voltage. The foreign voltage is detected on the transmission line in the circuit. A second logic signal is provided to configure the circuit to measure the foreign voltage, and the foreign voltage is measured.

US Patent:

6956945, Oct 18, 2005

Filed:

Mar 7, 2003

Appl. No.:

10/384300

Inventors:

Russell J. Apfel - Austin TX, US

Assignee:

Legerity, Inc. - Austin TX

International Classification:

H04M001/00

US Classification:

379413, 37939501, 37939901

Abstract:

A method and apparatus is for providing a phantom battery feed to reduce power consumption in a differential amplifier circuit. A voltage signal is driven onto a telecommunications line using a first amplifier and a second amplifier. A phantom battery feed is performed during a negative cycle of the voltage signal. Performing the phantom battery feed comprises: supplying a negative supply terminal of the first amplifier with a supply voltage that is one-half of a full scale supply voltage; and supplying a positive supply terminal of the second amplifier with a supply voltage that is one-half of the full scale supply voltage.

US Patent:

7113590, Sep 26, 2006

Filed:

Mar 7, 2003

Appl. No.:

10/384299

Inventors:

Russell J. Apfel - Austin TX, US

Assignee:

Legerity, Inc. - Austin TX

International Classification:

H04M 1/00

US Classification:

37939901, 37939004, 379402, 379398

Abstract:

A method and apparatus is provided for performing an active impedance differential current feedback. A signal is received. A current feedback of an output signal in an active feedback synthesis mode is performed based upon the signal. The active current feedback includes using an active feedback network for conditioning an output signal, converting the signal into a differential current signal, and summing at least two components of the differential current signal for performing a differential feedback.

US Patent:

7181002, Feb 20, 2007

Filed:

Mar 7, 2003

Appl. No.:

10/384296

Inventors:

Russell J. Apfel - Austin TX, US

Assignee:

Legerity, Inc. - Austin TX

International Classification:

H04M 19/00

US Classification:

379413, 379324

Abstract:

A method and apparatus is provided for using a single power supply in a dual mode fashion. A ringing signal is received. A waveform power supply signal based upon the ringing signal. An unbalanced output buffering function upon the signal to be conditioned using an unbalanced buffering circuit. Performing the unbalanced output buffering function includes switching between a plurality of power levels of the waveform power supply signal to maintain a predetermined maximum voltage across a plurality of devices relating to the unbalanced buffering circuit.

US Patent:

7215764, May 8, 2007

Filed:

Feb 6, 2002

Appl. No.:

10/068780

Inventors:

Russell J. Apfel - Austin TX, US

Assignee:

Legerity, Inc. - Austin TX

International Classification:

H04M 1/00
H04M 9/00

US Classification:

37939901, 379394, 379398, 37939902

Abstract:

A passive echo cancellation circuit for reducing echoes on a subscriber line includes an output driver adapted to drive a downstream signal on the subscriber line. First sensing circuitry is coupled to the output driver and adapted to sense a current on the subscriber line to generate a first voltage. A balancing network is adapted to receive at least a portion of the downstream signal. Second sensing circuitry is adapted to sense a current in the portion of the downstream signal passing through the balancing network to generate a second voltage. An upstream driver is adapted to subtract the second voltage from the first voltage to generate an upstream signal. A method for canceling echoes on a subscriber line includes driving a downstream signal on the subscriber line; sensing a current on the subscriber line to generate a first voltage; providing a portion of the downstream signal to a balancing network; sensing a current in the portion of the downstream signal passing through the balancing network to generate a second voltage; and subtracting the second voltage from the first voltage to generate an upstream signal.

US Patent:

7254229, Aug 7, 2007

Filed:

Mar 7, 2003

Appl. No.:

10/384304

Inventors:

Russell Apfel - Austin TX, US

Assignee:

Legerity, Inc. - Austin TX

International Classification:

H04M 1/00

US Classification:

379398, 379394, 37939901

Abstract:

A method and apparatus is provided for performing an active impedance feedback. A signal is received. An active feedback synthesis is performed based upon the signal. Performing the active feedback synthesis includes using an active feedback network for conditioning an output signal and performing a signal summation of at least two components of the conditioned output signal for feedback.

US Patent:

7260210, Aug 21, 2007

Filed:

Mar 7, 2003

Appl. No.:

10/384302

Inventors:

Russell Apfel - Austin TX, US

Assignee:

Legerity, Inc. - Austin TX

International Classification:

H04M 1/00

US Classification:

37939501, 379418, 37941301

Abstract:

A method and apparatus is provided for implementing an unbalanced subscriber line interface circuit with built-in ring circuit. A signal to be conditioned is received. An unbalanced output buffering function is performed upon the signal to be conditioned using an unbalanced buffering circuit. Performing the unbalanced output buffering function includes switching between a plurality of power supplies to maintain a predetermined maximum voltage across a plurality of devices relating to the unbalanced buffering circuit.