Communications methods and apparatus
CA 2251489 C · Owner: Nortel Networks Limited · Inventors: Terry, John Brian
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Ethernet frames are communicated via a telephone line between master and slave modems using half duplex communication of data and control information to avoid collisions, data to be transmitted being buffered in each modem. Different communication modes, involving different transmitted symbol frequencies modulation, methods, and bits per symbol to provide different transmission rates can be used, depending on errors on the line. To reduce signal attenuation and interference both of which increase with increasing frequency a lowest frequency communication mode is used for transmitting control information when there is no data in the buffer for transmission, whereas a higher transmission rate …
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 October 22, 1998 and granted January 21, 2003. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 22, 2018.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 22, 2020.
- 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.