Side tone correction circuit
June 26, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesTest apparatus for obtaining impedance settings for hybrid balance networks Automatic cable balancing network Automatically adjustable bidirectional-to-unidirectional transmission network Automatically adjustable bidirectional-to-unidirectional transmission network Hybrid circuit Balancing impedance included in a fork Method for adjusting the balancing impedance of a hybrid junction Universal channel unit switchable between two wire and four wire configurations Circuit for maintaining hybrid cancellation of signals in a communication system Patent #: 5054062 InventorAssigneeApplicationNo. 543432 filed on 06/26/1990US Classes:379/405, Electronic noninductive379/391, Sidetone control or hybrid circuit (e.g., induction coil)379/392, Suppression (e.g., antisidetone)379/398, LINE EQUALIZATION OR IMPEDANCE MATCHING379/402Hybrid circuitExaminersPrimary: Dwyer, James L.Assistant: Augustus, Jhancy Attorney, Agent or FirmInternational ClassH04M 001/00Foreign Application Priority Data1989-10-26 JPAbstractA conversion circuit for connecting a two-wire circuit and a four-wire circuit to each other comprises a transformer having a primary side and a secondary side, the primary side being connected to a two-wire circuit having a variable impedance, a first amplifying circuit having a first input terminal connected to the secondary side of the transformer for receiving an audio frequency signal from the two-wire circuit and a second input terminal, the first amplifying circuit having an output terminal connected to a reception-side line of a four-wire circuit, a second amplifying circuit having an input terminal connected to a transmission-side line of the four-wire circuit and an output terminal connected to the secondary side of the transformer for sending out an audio signal on the transmission-side line to the two-wire circuit, a plurality of impedance matching circuits having respective impedances each determined so as to simulate one state of the variable impedance of the two-wire circuit, and a switch for selectively connecting one of the plurality of impedance matching circuits to the second input terminal of the first amplifying circuit. | |
