Patents by Inventor Hans Drenkelfort

Hans Drenkelfort 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).

  • Echo-sounding apparatus
    Patent number: 4504931
    Abstract: Echo-sounding apparatus with circuitry for achieving enhanced recording on electrically sensitive paper is disclosed in which the gain of a variable gain amplifier is reduced exponentially depending on the input signal amplitude as soon as this amplitude exceeds a predetermined level. The signal generated by the variable gain amplifier is supplied to low pass and high pass filters which are connected to two inputs of a differential amplifier which controls the recording element.
    Type: Grant
    Filed: August 20, 1982
    Date of Patent: March 12, 1985
    Assignee: Honeywell-Elac-Nautik GmbH
    Inventor: Hans Drenkelfort