Method and apparatus for reducing residual far-end echo in voice communication networks
March 3, 2015. 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 ReferencesEcho canceller with adaptive residual center clipper controlled by echo estimate Echo cancelling using adaptive bulk delay and filter Echo canceller using end delay measurement Process and system for improving echo cancellation within a transmission network Process for determining an echo path flat delay and echo canceler using said process Echo suppressor Echo reduction circuit Voice controlled attenuation adjustment in telephone transmission circuits Residual echo elimination with proportionate noise injection Nonlinear processor for an echo canceller and method InventorsAssigneeApplicationNo. 398272 filed on 03/03/1995US Classes:370/289, Having residual echo cancellation or suppression379/406.07, Using attenuator379/406.12, Frequency domain analysis379/406.14Sub-band analysisExaminersPrimary: Hsu, Alpus H.Assistant: Rao, Seema S. Attorney, Agent or FirmInternational ClassH04B 003/20AbstractA method and apparatus are described for reducing, in communication signals received by a local network from a remote network (FAR-IN signals), that energy content that is attributable to echoes of signals transmitted into the local network (NEAR-IN signals). This is achieved, in part, by generating a time-varying TEMPLATE signal which represents the smoothed energy content of NEAR-IN signals delayed according to the echo path and attenuated by an estimated echo transmission loss. A non-linear processor passes the FAR-IN signal substantially without attenuation if it exceeds the threshold derived at least in part from the TEMPLATE, but attenuates the FAR-IN signal if it lies within a defined range below the threshold.Other References
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