Echo canceler having adaptive digital filter unit associated with delta-sigma modulation circuit
CA 2045250 C · Owner: Nec Corporation · Inventors: Takahashi, Yutaka
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An echo canceler comprises an adaptive digital filter circuit for producing an echo replica signal on the basis of a transmit digital signal and a first digital signal indicative of a far-end signal, and an adder for eliminating the echo signal from a received signal with reference to the echo replica signal, wherein the echo replica signal is modulated by a delta-sigma modulation circuit and, thereafter, converted into an analog signal for allowing the adder to operate on the echo replica signal and the received signal both in an analog form so that the adder with a narrow dynamic range can be available.
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 21, 1991 and granted March 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 21, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 21, 2013.
- 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.