Patents by Inventor John Thomas Dowdal

John Thomas Dowdal 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).

  • Calculation of clock skew using measured jitter buffer depth
    Patent number: 7177306
    Abstract: A system and method to measure the clock skew between transmitting and receiving devices operating with independent clock sources over a packet network is described. To provide adaptive playout in an IP telephony device without a sequencing scheme in the packets, the clock skew is measured and recorded. Using a PCM resampler that is implemented with an interpolation filter bank of FIR subfilters, the change in depth of the playout buffer during transmission is analyzed, and this change infers the clock rate associated with the transmission.
    Type: Grant
    Filed: September 30, 2002
    Date of Patent: February 13, 2007
    Assignee: Texas Instruments Incorporated
    Inventors: John Thomas Dowdal, Qin Su
  • Calculation of clock skew using measured jitter buffer depth
    Publication number: 20040062252
    Abstract: A system and method to measure the clock skew between transmitting and receiving devices operating with independent clock sources over a packet network is described. To provide adaptive playout in an IP telephony device without a sequencing scheme in the packets, the clock skew is measured and recorded. Using a PCM resampler that is implemented with an interpolation filter bank of FIR subfilters, the change in depth of the playout buffer during transmission is analyzed, and this change infers the clock rate associated with the transmission.
    Type: Application
    Filed: September 30, 2002
    Publication date: April 1, 2004
    Inventors: John Thomas Dowdal, Qin Su