Self calibration arrangement for a voice switched speakerphone
CA 2004169 C · Owner: American Telephone And Telegraph Company · Inventors: Erving, Richard Henry
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An electrical calibration circuit in a voice switched adaptive speakerphone accurately determines the operating parameters of the speakerphone for optimal performance before operation. This is achieved by updating thresholds used to determine when the speakerphone should be in each of three possible operating states; transmit receive or idle. During, operation, these thresholds are compared with transmit and receive signal strength levels to determine the state of the speakerphone. The thresholds are updated to counteract the effects of variation and aging of hardware circuits inthe speakerphone and are obtained by having the calibration circuit generate a test tone signal which is passed …
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 November 29, 1989 and granted July 19, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 29, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 29, 2011.
- 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.