Method and arrangement of echo elimination in digital telecommunications system
CA 2071241 C · Owner: Nec Corporation · Inventors: Sano, Hideo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In order to reduce the complexity of an adaptive digital filter used to cancel delayed network echoes a, delay circuit is arranged in series therewith end arranged to compensate for the delay inherent with a speech codec. In the case of a variable delay circuit the degree by which the echo is delayed is detected in the adaptive digital filter and used to modify the delay time. A gain control arrangement can be provided and used to reduce the gain of the received signal when the near-end party is talking and the adaptive capacity of the adaptive digital filter is exceeded.
Read the whole patent
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 June 15, 1992 and granted April 15, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 15, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 15, 2014.
- 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.