Patents by Inventor Kar B. Chan

Kar B. Chan 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: 5416778
    Abstract: A digital radio communication system (1) is known, for example based on the DECT standard, in which radio communication of digital speech or data between primary (BS1) and secondary (MS1) stations takes place via duplex FDMA/TDMA connection. Channel allocation therein is dynamic. If necessary because of the receiving conditions, the secondary station (MS1) can initiate a so-called handover by searching for a free channel offering better receiving conditions. In accordance with the invention, this handover is seamless. Digital speech bursts are exchanged via different time slots (ts) during a number of frames (fr), these being digital speech data and copy digital speech data. After verification that the copy data is valid, i.e. that communication has been established via a free channel, handover takes place. The original data and the copy data are stored in a cyclic buffer (SB5) so that the phase shift (d) between the original data and the copy data is eliminated.
    Type: Grant
    Filed: June 3, 1993
    Date of Patent: May 16, 1995
    Assignee: U.S. Philips Corporation
    Inventors: Kar B. Chan, Cornelis C. M. Schuur, Roelof J. H. De Haas
  • Patent number: 5051608
    Abstract: Circuit arrangement including a parabolic generator for supplying a periodic, substantially parabolic signal to an output terminal during a trace time and an arcuate signal generator for supplying an arcuate signal, which has the shape of, for example, a half sine wave, during a retrace time. At the start of the retrace time, the arcuate signal and its derivatives are given values which are substantially equal to the corresponding values of the parabolic signal at the end of the trace time. The arcuate signal generator is adapted to generate the arcuate signal in a time-discrete manner under the control of switching pulses supplied by a pulse circuit. The pulse circuit is adapted to supply a constant number of switching pulses for generating the arcuate signal in spite of variations in the retrace time, so that the arcuate signal and its derivative assume values which are substantially equal to the corresponding values of the parabolic signal at the start of the trace time.
    Type: Grant
    Filed: April 10, 1990
    Date of Patent: September 24, 1991
    Assignee: U.S. Philips Corporation
    Inventors: Hendrik Ten Pierick, Kar B. Chan, Steven J. Koelewijn