The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 08, 2007
Filed:
Feb. 06, 2002
Russell J. Apfel, Austin, TX (US);
Russell J. Apfel, Austin, TX (US);
Legerity, Inc., Austin, TX (US);
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.