Patent ReferencesAutomatic loss control circuit Ring tone detection for a telephone system Automatic impedance matching with potential monitoring means Digital line card having universal port for upgrading electronic messaging system Modem having an improved line interface circuit, in particular for a computer Circuit for a line simulating device Signal interface circuit with selectable signal interface parameters IC card-type modem and method for communicating data by IC card-type modem Patent #: 5623514 InventorsAssigneeApplicationNo. 629840 filed on 04/11/1996US Classes:379/398, LINE EQUALIZATION OR IMPEDANCE MATCHING375/222, Modems (data sets)379/394, Impedance matching or line equalizing379/399.01, SUBSCRIBER LINE OR TRANSMISSION LINE INTERFACE379/402Hybrid circuitExaminersPrimary: Matar, Ahmad F.Assistant: Saint-Surin, Jacques M. Attorney, Agent or FirmInternational ClassesH04M 007/04H04B 001/38 AbstractA system and method having automatic selection of impedance values for matching against unknown line impedances. The method stores an expected set of desired return loss measurements at given frequencies and matches the calculated set against the actual measured return losses to arrive at a close approximation of the line impedance. The system is then adjusted based upon this determined close approximation. The starting point for the stored set are standard models established for each network. In situations where the actual varies greatly from the predicted, a different model is selected and the expected scores for that model are used. | |