Direct modulation phase-shift-keying system and method
CA 2019178 C · Owner: Naito, Takao · Inventors: Watanabe, Shigeki; Kiyonaga, Tetsuya; Onoda, Yoshihito
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A direct modulation PSK system and method in, a coherent optical fiber transmission system in which, an injection current supplied to a laser diode is adapted to be directly varied is disclosed. In this system or method, a modulating current pulse is superposed on a bias current for the laser diode so that a specified phase condition may be satisfied. Thereby a differential coding circuit and an external modulator being indispensable for a DPSK system become unnecessary and, in addition, the system becomes less susceptible to the influence of wavelength dispersion than the DPSK system and able to reproduce the carrier.
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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 June 18, 1990 and granted May 24, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 18, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 18, 2012.
- 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.