Feedback level estimator between loudspeaker and microphone
CA 2129102 C · Owner: Chu, Peter L. · Inventors: Chu, Peter L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An improved echo cancelling device (18) for reducing the effects of acoustic feedback between a loudspeaker and microphone in a communication system. The device includes an adjustable filter (50) for receiving a loudspeaker signal and generating in response thereto an echo estimation signal. The device subtracts (54) the echo estimation signal from the microphone signal to produce an echo corrected microphone signal. During periods of time when the microphone signal is substantially derived from acoustic feedback between the loudspeaker and the microphone the device , adjusts (58) transfer characteristics of the filter (52) to reduce the echo corrected microphone signal. The improvement …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed January 8, 1993 and granted September 14, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 8, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 8, 2015.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.