Patents by Inventor John D. Markus

John D. Markus 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).

  • Beacon signal receiving system
    Patent number: 5657026
    Abstract: A method and apparatus for locating and tracking a portable transmitter that may be deposited with currency or other items desired to be tracked, comprising a doppler antenna array, analog antenna switching, radio frequency and intermediate frequency circuitry and a digital signal processor, exhibiting increasing sensitivity, accuracy, and range.
    Type: Grant
    Filed: January 26, 1996
    Date of Patent: August 12, 1997
    Assignee: Electronic Tracking Systems, Inc.
    Inventors: Jerry W. Culpepper, John D. Markus, Lawrence M. Smith, Zhaoliang Chen