Telephonic communications – Subscriber line or transmission line interface – Hybrid circuit
Reexamination Certificate
2005-11-29
2005-11-29
Tran, Sinh (Department: 2644)
Telephonic communications
Subscriber line or transmission line interface
Hybrid circuit
C379S394000, C379S398000, C379S399010, C379S413020, C379S413030, C379S413040, C379S413010
Reexamination Certificate
active
06970557
ABSTRACT:
A cordless telephone-to-sound card interface adapter provides a connection between any standard cordless telephone system and a sound card of a computer for PC-to-PC or PC-to-telephone voice communications over the Internet. The interface adapter includes a hybrid transformer circuit for interfacing a two-wire circuit of the cordless telephone and a four-wire circuit of the computer sound card. This hybrid transformer circuit cancels out the voice echo that would otherwise exist due to mismatched impedances between the two media and/or from leakage of the signal being transmitted and received on the same pair of telephone lines. A Universal Serial Bus (USB) plug may be provided to receive a bias voltage from the PC for biasing circuits of the cordless telephone system through the interface adapter. Advantageously, the preferred interface adapter utilizes 100% passive components for a low-cost yet effective means to provide mobility for an end user during voice communications over the Internet.
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NVG, Inc.
Oskorep, Esq. John J.
Singh Ramnandan
Tran Sinh
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