Patents by Inventor Dan R. F. Oprea

Dan R. F. Oprea 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).

  • Digitally controlled ringer signal generation
    Patent number: 5323456
    Abstract: A method and apparatus, of producing an alarm or ringing signal by providing a first pulse signal having a predetermined pulse width to define an alarm or ringing signal amplitude, and modulating the pulse signal with a second pulse signal having a pulse rate at least an order lower than the frequency of the first pulse signal to define the alarm or ringing signal frequency, averaging the modulated first pulse signal in a loudspeaker voice coil and reproducing the result in the loudspeaker to provide the alarm or ringing signal.
    Type: Grant
    Filed: June 5, 1992
    Date of Patent: June 21, 1994
    Assignee: Mitel Corp.
    Inventor: Dan R. F. Oprea