Patents by Inventor Xiaofen Chen

Xiaofen Chen 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).

  • Measurement test set and method for in-service measurements of phase noise
    Patent number: 6246717
    Abstract: A system and method for in-service transmitter phase noise measurements determines phase nonlinearity by way of comparing unfiltered signal samples and regenerated reference signal samples to calculate phase nonlinearity error. Linear distortion is removed from the received signal samples in order to truly characterize nonlinear behavior of the transmitter. The unfiltered signal samples are generated without applying the receiver shaping filtering. Reference signal samples are regenerated from estimated transmitted symbols derived from the unfiltered signal samples. The transmitted symbols are estimated using a segmented slicer which dynamically estimates constellation decision levels from the unfiltered signal samples. A weighted, least-square based polynomial regression is performed on phase error samples of the unfiltered signal samples to estimate a phase nonlinear error function while suppressing the impact of other non-systematic distortions.
    Type: Grant
    Filed: November 3, 1998
    Date of Patent: June 12, 2001
    Assignee: Tektronix, Inc.
    Inventors: Xiaofen Chen, Linley F. Gumm, Dana E. Whitlow, Larry R. Lockwood