Frequency discriminator and heterodyne receiver provided with the frequency discriminator for coherent lightwave communications
CA 2071624 C · Owner: Fujitsu Limited · Inventors: Onaka, Hiroshi; Chikama, Terumi; Naito, Takao
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In a frequency discriminator in which it is adapted such that a signal to be subjected to frequency discrimination is divided into two signals and mixed together after one of the divided signals has been given a delay time, the frequency discriminator disclosed is additionally provided with a filter, of which cutoff frequency is set up according to the delay time disposed in the front stage and, thereby both, improvement of accuracy in frequency identification and expansion of the capture range can be attained.
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 18, 1992 and granted September 29, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 18, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 18, 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.