Fujitsu Corporation

Nippon Telegraph and Telephone Public Corporation

Hirokazu Fukui

Kiichi Matsuda

Mitsuo Kakuishi

Kaoru Chujo

Jin Abe

Atsushi Iwata

Akihiko Ito

Toshitaka Tsuda

Takeshi Okazaki

Tadahiro Saito

Hirohisa Gambe

Toshi Ikezawa

Shin-ichi Maki

Takao Kaneko

Kazuhiro Kaneko

Shin-Ichi Maki

This invention relates to a functional device such as an FPGA carrying out a necessary function by programming, and provides a functional device, a function maintaining method and a function maintaining program which can maintain a function continuously. A plurality of function parts (FPGAs) is provided, and a function is maintained by switching from a function part, in which a failure is occurring, to a function part under stand-by. The plurality of function parts, a failure detection part (failure detection circuits) and a switching part (switching circuits) are provided, and a function part under operation and a function part under stand-by a reset. That is, the function part in which the failure is occurring is made into a stand-by state, and the function part which is under stand-by is made to operate. Therefore, the continuous function can be maintained without stopping the operation of a system due to the failure occurring in the function part, and the reliability of the system is heightened by the maintenance of the function.

Functional device, function maintaining method and function maintaining program

An adaptive echo canceller for suppressing an echo in an input signal by a pseudo echo, includes a pseudo echo generation filter having a predicted impulse response sequence of an echo path as filter coefficients thereof for generating a pseudo echo, a coefficient renewal part for adaptively renewing the filter coefficients of the pseudo echo generation filter, and a part for suppressing an echo by the pseudo echo which is generated by the pseudo echo generation filter. The coefficient renewal part includes a part for dividing renewed filter coefficients into a plurality of groups each having a certain number of renewed filter coefficents, and a part for successively selecting one group with a predetermined period and carrying out a correction process with respect to the renewed filter coefficients within the selected group, where the correction process corrects an accumulation of errors of renewal processes.

Adaptive echo canceller

A differential coding circuit including a subtracter, a quantizer for quantizing a differential signal from the subtracter, and a predicted signal generating circuit for generating a predicted signal on the basis of a quantized differential signal from the quantizer. The subtracter subtracts the quantized differential signal of the quantizer and the predicted signal from the sampled input signal. The critical path of the circuit is shortened, therefore the operation speed of the differential coding circuit increases.

Differential coding circuit with reduced critical path applicable to DPCM

A phase-locked loop circuit provides a phase comparator which receives input signals through a first input terminal, a loop filter which receives a first output and a second output of the phase comparator, and a voltage-controlled oscillator which produces output signals of an oscillation frequency proportional to the first output and the second output of the loop filter. The signals corresponding to the output signals produced by the voltage-controlled oscillator are supplied to a second input terminal of the phase comparator so that the phase of the signals supplied to the first input terminal of the phase comparator is compared with the phase of the signals supplied to the second input terminal. In the present invention, the loop filter comprises a first capacitor connected to the output terminal of the loop filter, second and third capacitors, each having a terminal connected to the output terminal of the loop filter, and a charging circuit for electrically charging the first, second, and third capacitors. The charging circuit is connected in parallel with the second capacitor. A discharging circuit for discharging the first, second, and third capacitors is connected in parallel with the third capacitor.

Phase-locked loop using integrated switched filter

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Kawasaki, Japan

Hirokazu Fukui