Patents by Inventor Ken Demarest

Ken Demarest 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).

  • Method and apparatus to compensate for polarization mode dispersion
    Patent number: 6647176
    Abstract: A polarization scrambler and a polarization mode dispersion (PMD) compensation system compensate for PMD on an active optic fiber. The polarization scrambler scrambles a state of polarization of an optical signal that carries user information. The PMD compensation system then receives the optical signal over the active optic fiber. The PMD compensation system measuring a differential group delay and principal states of polarization of the PMD in the active optic fiber. The PMD compensation system then determines a modification of the optical signal based on the differential group delay and the principal states of polarization of the PMD. The PMD compensation system modifies the optical signal in the active optic fiber to compensate for PMD based on the determination of the modification. The PMD compensation system then transmits the optical signal.
    Type: Grant
    Filed: August 15, 2002
    Date of Patent: November 11, 2003
    Assignee: Sprint Communications Company, L.P.
    Inventors: Hok Yong Pua, Chris Allen, Ken Demarest, Ron Hui, Kumar Vijay Peddanarappagari
  • Method and apparatus for recovering an optical clock signal
    Patent number: 6542274
    Abstract: A clock recovery system recovers an optical clock signal from an optical data signal that is wavelength and data rate independent. The system splits the optical data signal into a first optical data signal and a second optical data signal. The system then transmits the first optical data signal and the second optical data signal in opposite directions around a fiber loop. In the fiber loop, the system modulates and amplifies the first optical data signal to generate a modulated-amplified first optical data signal. The system then recovers the optical clock signal after the modulated-amplified first optical data signal and the second optical data signal interact in the fiber loop.
    Type: Grant
    Filed: October 29, 1999
    Date of Patent: April 1, 2003
    Assignee: Sprint Communications Company, LP
    Inventors: Ken Demarest, Chris Johnson, Chris Allen, Rongqing Hui, Benyuan Zhu
  • Method and apparatus to compensate for polarization mode dispersion
    Patent number: 6459830
    Abstract: A polarization scrambler and a polarization mode dispersion (PMD) compensation system compensate for PMD on an active optic fiber. The polarization scrambler scrambles a state of polarization of an optical signal that carries user information. The PMD compensation system then receives the optical signal over the active optic fiber. The PMD compensation system measuring a differential group delay and principal states of polarization of the PMD in the active optic fiber. The PMD compensation system then determines a modification of the optical signal based on the differential group delay and the principal states of polarization of the PMD. The PMD compensation system modifies the optical signal in the active optic fiber to compensate for PMD based on the determination of the modification. The PMD compensation system then transmits the optical signal.
    Type: Grant
    Filed: February 8, 2000
    Date of Patent: October 1, 2002
    Assignee: Sprint Communications Company L.P.
    Inventors: Hok Yong Pua, Chris Allen, Ken Demarest, Ron Hui, Kumar Vijay Peddanarappagari