Fujitsu Corporation

Seiichi Yamato

Seiji Miyoshi

Misao Fukuda

Kazuyoshi Maruyama

Yutaka Awata

Tomoyuki Sakata

Katsumi Sugawa

Hironori Kadota

Shinji Ohta

Noboru Kamei

Kazuyoshi Okuma

Kouji Tokiwa

Kinji Kawada

A high-speed sprchronous multiplexing apparatus has a low-speed device and a high-speed device and employs electrical signals to interface the devices with each other. The low-speed device is connected to a low-speed digital circuit. The high-speed device is connected to a high-speed synchronous multiplexing circuit. The apparatus also has a clock supplier for supplying a reference clock signal that defines a communication rate, to each of the low- and high-speed devices. The apparatus further has an alarm processor for separating faults in the low- and high-speed devices. The low- and high-speed devices are interfaced with each other with the use of the reference clock signal and electrical STM-0/STS-1 signals that employ a frame signal synchronized with the reference clock signal.

High-speed synchronous multiplexing apparatus

Initial training apparatus for use in a transmitter and receiver

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. Instead of or accompanied by the greater precision, the contents of the main memory are updated directly based on the error between the pseudo signal and an input signal or based on a step size corresponding to the error, depending on whether the error is relatively large or relatively small, respectively.

Digital adaptive filter and method of convergence therein

Growing community of inventors

Fukuoka, Japan

Seiichi Yamato