Patents by Inventor Kouji Tokiwa

Kouji Tokiwa 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).

  • Digital adaptive filter and method of convergence therein
    Patent number: 5007044
    Abstract: Disclosed is a digital adaptive filter and a method of cancelling an echo component generated by a partial return of a transmission signal to a receiving side. The digital adaptive filter comprises: a main memory unit for storing a first echo replica which can be stored or read by using the parallel signal from a main tap unit as an address signal, at least one submemory unit for storing a second echo replica which can be stored or read by using the parallel signal from said subtap unit as an address signal, and an adding circuit for adding the first echo replica and the second echo replica. The second echo replica stored in the at least one submemory unit has a greater precision than the precision of the first echo replica stored in the main memory unit, and thus the accumulated error due to memory division can be reduced.
    Type: Grant
    Filed: July 20, 1989
    Date of Patent: April 9, 1991
    Assignee: Fujitsu Limited
    Inventors: Seiji Miyoshi, Misao Fukuda, Seiichi Yamato, Kouji Tokiwa, Kazuyoshi Maruyama