Patents by Inventor David A. Tofte

David A. Tofte 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).

  • Three-track sterophonic system
    Patent number: 4747142
    Abstract: In a stereophonic reproduction system, a true center-channel signal is derived by combining the left and right signals into a monophonic signal, and canceling and overriding this monophonic signal with a second modified monophonic signal, the latter derived by combining properly bandpassed left and right signals that have been compressed, combined, and expanded. True left-and true right-channel signals are subsequently derived by subtracting the true center-channel signal voltage from the left and right signal voltages.
    Type: Grant
    Filed: July 25, 1985
    Date of Patent: May 24, 1988
    Inventor: David A. Tofte