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Expired Canadian patentCanada

Channel selection in an optical tdma network

CA 2247189 C · Owner: British Telecommunications Public Limited Company · Inventors: Widdowson, Terence; Pitcher, Danny Robert; Moodie, David Graham

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Abstract From the Canadian patent

A receiver at a node in an optical network receives an optical clock signal and a OTDM datastream. A detector converts the clock signal to the electrical domain. A variable delay stage applies a selected delay to the clock signal in the electrical domain. A non-linear electro-optic modulator which may be an electro-absorption modulator, receives the OTDM datastream at its optical input. An electrical control input of the modulator is connected to the output of the variable delay stage. The electro-optic modulator outputs an OTDM channel selected by setting the delay of the variable delay stage. The variable delay stage may comprise a number of logic gates particularly AND , gates, …

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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 February 14, 1997 and granted June 25, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 14, 2017.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 14, 2019.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledFebruary 14, 1997
GrantedJune 25, 2002
Term endedFebruary 14, 2017
Patent numberCA 2247189 C
Classification (IPC)H04J14/08 +2 more

Timeline

Timeline From CIPO dates

1998200020022004200620082010201220142016Application filedFeb 14, 1997Patent grantedJune 25, 2002Term endedFeb 14, 2017

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.