Optical communication system
CA 2078076 C · Owner: Watanabe, Shigeki · Inventors: Watanabe, Shigeki
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An optical communication system in which light is modulated in sending equipment according to a composed signal obtained by mixing a signal frequency-multiplexed at the microwave level in a coherent SCM optical communication system with an unmodulated signal out of the frequency band of the frequency-multiplexed signal. The resultant modulated light is optical-heterodyne-detected. A demodulating unit demodulates a frequency-multiplexed signal according to an electric signal delayed by a delay unit by the time equal to the time delay in an unmodulated component extracting unit. Only the frequency components of a frequency-multiplexed signal and an unmodulated signal must be received in …
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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 September 11, 1992 and granted July 28, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 11, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 11, 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.