Patents by Inventor David D. Casey

David D. Casey 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: 5812591
    Abstract: A GPS frequency converter is provided, according to the present invention, to down-convert the frequency of an incoming GPS signal. The converter includes first and second mixers, the former of which receives the incoming RF signal and a signal from a local oscillator. The local oscillator signal is increased by a factor of 98 and then subtracted from the incoming RF signal to produce a first intermediate frequency signal (IF). The first IF signal is then passed to the second mixer which subtracts the frequency of the local oscillator therefrom to produce a second intermediate frequency signal (IF). The second IF signal is passed through a limiter and output as the frequency converted signal.
    Type: Grant
    Filed: September 23, 1994
    Date of Patent: September 22, 1998
    Assignee: Garmin Corporation
    Inventors: Paul K. Shumaker, David D. Casey, Gary L. Burrell
  • Patent number: 5111150
    Abstract: A precision phase shift system presents advantageous utility in navigation systems using signals from global positioning satellites. In particular, the system hereof provides precise control over successive phase-shifting steps of output signals which allows precise matching with corresponding object signals for subsequent decoding thereof.
    Type: Grant
    Filed: September 26, 1990
    Date of Patent: May 5, 1992
    Assignee: Garmin Corporation
    Inventor: David D. Casey