Patents by Inventor Shigeyuki Akagi

Shigeyuki Akagi 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 for carrying out loopback test
    Patent number: 4271513
    Abstract: The present invention discloses a method for carrying out a loopback test in a data communication system having a first data communication station, a second data communication station and a transmission line connected therebetween. The first data communication station transmits a succession of a first pseudo-random noise signal, a loopback test signal and a second pseudo-random noise signal to the second data communication station by utilizing a usual information data channel, and requires no special channel for carrying out the loopback test. When the second data communication station detects the first pseudo-random noise signal, it transmits the loopback test signal to the first data communication station in order to check the coincidence of the transmitted and the received loopback test signals. The second pseudo-random noise signal denotes the end of the loopback test.
    Type: Grant
    Filed: May 9, 1979
    Date of Patent: June 2, 1981
    Assignees: Nippon Telegraph and Telephone Public Corporation, Fujitsu Limited, Oki Electric Industry Co., Ltd., Nippon Electric Co., Ltd.
    Inventors: Hiroshi Maejima, Noriaki Fujimura, Takahiro Shibuya, Shigeyuki Akagi