Patents by Inventor Tom M. Luk

Tom M. Luk has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6871304
    Abstract: Methods and apparatus are provided for adjusting slicing parameters, such as a voltage threshold and a phase sampling point, used in recovering 1's and 0's from a signal so as to reduce a bit error rate (BER) of the signal. The BER is modelled as a second order polynomial of the slicing parameters. The BER is repeatedly determined from a Forward Error Correction corrected bits counter. For each BER measurement the model is updated, using for example a recursive least squares fit. New values of the slicing parameters are then determined by carrying out an iteration of an optimization, such as a Levenberg-Marquardt optimization, using the model. The new values of the slicing parameters are passed to a Clock and Data Recovery module. Various conditions are checked before updating the model or determining the new values of the slicing parameters, such as changes in signal power or high BERs which exceed the error correction capabilities of the forward error correction.
    Type: Grant
    Filed: August 12, 2002
    Date of Patent: March 22, 2005
    Assignee: Nortel Networks Limited
    Inventors: Sevgui Hadjihassan, Tom M. Luk
  • Patent number: 6785308
    Abstract: A system and method for spectral conditioning an optical signal. An optical filter has an input for receiving an emitted optical signal and an output providing a filtered optical signal. The filter has a corresponding filter profile which includes a high wavelength skirt at an upper wavelength region of the filter profile. A laser is optically coupled to the optical filter input and emits the emitted optical signal. The laser is controllable to emit the optical signal at a wavelength proximate to the optical filter high wavelength skirt.
    Type: Grant
    Filed: March 28, 2002
    Date of Patent: August 31, 2004
    Assignee: Nortel Networks Limited
    Inventors: Peter J. Dyer, Tom M. Luk, Jean-Philippe Martel
  • Publication number: 20040030965
    Abstract: Methods and apparatus are provided for adjusting slicing parameters, such as a voltage threshold and a phase sampling point, used in recovering 1's and 0's from a signal so as to reduce a bit error rate (BER) of the signal. The BER is modelled as a second order polynomial of the slicing parameters. The BER is repeatedly determined from a Forward Error Correction corrected bits counter. For each BER measurement the model is updated, using for example a recursive least squares fit. New values of the slicing parameters are then determined by carrying out an iteration of an optimization, such as a Levenberg-Marquardt optimization, using the model. The new values of the slicing parameters are passed to a Clock and Data Recovery module. Various conditions are checked before updating the model or determining the new values of the slicing parameters, such as changes in signal power or high BERs which exceed the error correction capabilities of the forward error correction.
    Type: Application
    Filed: August 12, 2002
    Publication date: February 12, 2004
    Inventors: Sevgui Hadjihassan, Tom M. Luk
  • Publication number: 20030185258
    Abstract: A system and method for spectral conditioning an optical signal. An optical filter has an input for receiving an emitted optical signal and an output providing a filtered optical signal. The filter has a corresponding filter profile which includes a high wavelength skirt at an upper wavelength region of the filter profile. A laser is optically coupled to the optical filter input and emits the emitted optical signal. The laser is controllable to emit the optical signal at a wavelength proximate to the optical filter high wavelength skirt.
    Type: Application
    Filed: March 28, 2002
    Publication date: October 2, 2003
    Applicant: Nortel Networks Limited
    Inventors: Peter J. Dyer, Tom M. Luk, Jean-Philippe Martel
  • Patent number: 6519302
    Abstract: The invention provides a method and apparatus for efficiently regenerating an incoming data signal at a sampling point which is continually optimized independently of the regeneration process. While the incoming data signal is being regenerated in a regeneration unit, the invention uses a monitoring unit for concurrently optimizing the slicing threshold and sampling phase used in the regeneration unit without disturbing the on-going data regeneration. The invention uses a master-slave arrangement to regenerate the incoming data signal whereby the regenerating unit is updated with a new slicing threshold and sampling phase only after the new slicing threshold and sampling phase are fully optimized by the monitoring unit. In this way, the data regeneration can proceed unaffected by the optimization of the slicing threshold and sampling phase which, as a result can be continuously optimized without inducing any errors into the regenerated data.
    Type: Grant
    Filed: October 18, 2000
    Date of Patent: February 11, 2003
    Assignee: Nortel Networks Limited
    Inventors: Paul A. Bruce, Tom M. Luk
  • Patent number: 6188737
    Abstract: The invention provides a method and apparatus for efficiently regenerating an incoming data signal at a sampling point which is continually optimized independently of the regeneration process. While the incoming data signal is being regenerated in a regeneration unit, the invention uses a monitoring unit for concurrently optimizing the slicing threshold and sampling phase used in the regeneration unit without disturbing the on-going data regeneration. The invention uses a master-slave arrangement to regenerate the incoming data signal whereby the regenerating unit is updated with a new slicing threshold and sampling phase only after the new slicing threshold and sampling phase are fully optimized by the monitoring unit. In this way, the data regeneration can proceed unaffected by the optimization of the slicing threshold and sampling phase which, as a result can be continuously optimized without inducing any errors into the regenerated data.
    Type: Grant
    Filed: November 24, 1999
    Date of Patent: February 13, 2001
    Assignee: Nortel Networks Limited
    Inventors: Paul A. Bruce, Tom M. Luk