Fujitsu Corporation

Takeshi Asahina

Takashi Kaku

Ryoji Okita

Toyomi Obikawa

Hideo Miyazawa

Shigeru Hashimoto

Noboru Kawada

Tohru Ogawa

Masaru Yasunaga

A limiter is connected with the output of a PLL to limit the amplitude of the output from the PLL. The output from limiter is supplied to a voltage-controlled oscillator (VCXO). The limiter determines the difference between the input signal and the output signal. If the difference exceeds a predetermined value, the change in the output from the limiter is limited to the predetermined value. If the difference does not exceed the predetermined value, the change in the output is considered to be a difference value.

PLL controller, method of PLL control, and limiter

A transmission apparatus such as a modem has a receiving unit which receives information and a clock-supplying unit which supplies a clock signal to the receiving unit. It further has an instantaneous dropout detection unit which detects the occurrence of an instantaneous dropout on the receiving circuit and a clock supply control unit which stops the supply of a clock to the receiving unit for a prescribed amount of time when the instantaneous dropout detection unit detects an instantaneous dropout, the stopping of the clock supply causing holding of receiving parameters and the restarting of clock supply causing restarting of the receiving operation.

Transmission apparatus and control method therefor

A non-interrupted operation control apparatus for a modem is provided for the purpose of preventing communications errors caused by the corruption of control parameter data stored within the modem, and circuit hangs, wherein an initialization unit is provided for the purpose of periodically initializing the modem at prescribed time intervals during a period of no communications via the modem. The initialization unit performs resetting of the hardware and setting of control parameters anew at prescribed time intervals.

Non-interrupted operation control apparatus for a modulator-demodulator

A transmission apparatus, connected via a hybrid circuit to a line, such as a modulator-demodulator which can perform stable echo cancellation, whether the level of the far-end echo is high or not, provided with a transmission unit which generates a transmission signal to be transmitted to the line via the hybrid circuit, a reception unit which receives the reception signal supplied from the line via the hybrid circuit, and a superimposing means for superimposing the reception signal applied to the hybrid circuit onto the transmission signal. The transmission signal onto which the reception signal is superimposed by the superimposing means is transmitted to the line via the hybrid circuit.

Transmission apparatus having echo cancellation facility

A communication network includes a first communication device (10, 64), a second communication device (14, 66) connected through a switched network (12, 68) to the first communication device (10, 64), in order to carry out a communication with the first communication device (10, 64), and a monitor/management device (16, 60) for performing a monitoring and/or management of the first and the second communication devices. In a first embodiment of the present invention, a disconnection factor requiring a disconnection between the first and the second communication devices is detected in the second communication device, and is transmitted to the first communication device, and thereafter, a connection between the first and the second communication devices is disconnected. In a second embodiment of the present invention, monitor/management information from the monitor/management device to the second communication device is once retained in the first communication device and is transmitted to the second communication device while both are connected to thereby carry out a user communication. Monitor/management information from the second communication device to the monitor/management device is transmitted to the first communication device while both are connected, and once retained in the first communication device.

Growing community of inventors

Kawasaki, Japan

Takeshi Asahina