Patents by Inventor Hirohumi Masukawa

Hirohumi Masukawa 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).

  • Method and apparatus of measuring a subscriber line
    Patent number: 5073920
    Abstract: A subscriber line measuring method and apparatus can charge a line capacitance of a telephone subscriber line in a very short time as compared with a prior art by charging the line capacitance by a predetermined current without use of a high resistor (100 k.OMEGA.) in a conventional measuring apparatus, and thereby can measure an impedance of the telephone subscriber line in a very short time with high accuracy.
    Type: Grant
    Filed: August 17, 1990
    Date of Patent: December 17, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Hirohumi Masukawa, Makoto Hisamura