Fujitsu Corporation

Masato Oota

Nobukazu Koizumi

Kazuhiko Hatae

Masashi Sato

Yasuo Ohtomo

Daisuke Sasaki

Manabu Yamazaki

Tomoki Katou

Yohei Koganei

Koji Migita

Nobuaki Kawasoe

Akiko Furuya

Yuya Imoto

Hisao Nakashima

A signal processing circuit includes: a processor configured to adjust phases of reception samples which is supplied at a supply interval, according to a phase adjustment amount; and a processing circuit including a finite impulse response (FIR) filter with taps and configured to process, by the FIR filter, each of the reception samples and output output symbols at an output interval different from the supply interval, the processor is configured to: derive initial values of tap coefficients for the respective taps; and derive the phase adjustment amount such that a center of centroids of the tap coefficients at respective output time points of the output symbols coincides with a center of a number of taps of the FIR filter, the tap coefficients at respective output time points of the output symbols being set according to a deviation between the supply interval and the output interval and the initial values.

Signal processing circuit and optical receiving device

An amplitude adjustment circuit includes a memory that stores correspondence information between frequency distributions of an amplitude and adjustment coefficients, a processor configured to generate a frequency distribution of amplitude of data for which adaptive equalization processing has been executed, acquire the correspondence information between frequency distributions of the amplitude and adjustment coefficients from the memory, select the adjustment coefficient based on a result of comparison between the frequency distributions included in the correspondence information acquired by the acquiring unit and the frequency distribution generated by the generating unit, and adjust a gain of the data based on the adjustment coefficient selected by the selecting unit.

Amplitude adjustment circuit, digital coherent receiver, and amplitude adjustment method

A circuit includes a calculation circuit configured to calculate a noise power of a predetermined-training-sequence pattern repeatedly included in a first signal input into an adaptive equalizer, based on a second signal obtained by compensating the first signal by a compensation circuit, a channel-estimation value based on the second signal, and the predetermined-training-sequence pattern; and an average circuit configured to obtain an average value of estimation values of frequency offsets based on the predetermined-training-sequence pattern having the noise power equal to or smaller than a predetermined power, among estimation values of frequency offsets based on the predetermined-training-sequence pattern, wherein the compensation circuit is configured to compensate a frequency offset of the predetermined-training sequence pattern based on the average value and thereby obtain the second signal, and the adaptive equalizer is configured to perform adaptive-equalization processing of the first signal with a setting value based on the second signal.

Adaptive equalization circuit, digital coherent receiver, and adaptive equalization method

A signal processing apparatus includes: a filter; and a filter control circuit, wherein the filter control circuit is configured to: detect a power of signals output from the filter; determine one of a plurality of numerical ranges to which the power belongs; update a filter coefficient of the filter according to a determination result; count a number of the signals having the power of a first value or more; set an invalid area which becomes a target not to be determined for each of one or more boundaries between the plurality of numerical ranges when the number of the signals becomes a second value or more; and control a width of the invalid area based on the number of signals.

Signal processing apparatus, signal processing method, and signal processing system

An optical receiving device includes: an adaptive equalizer that includes a position estimation unit configured to estimate, based on a first signal component and a second signal component of a reception signal generated by reception of a training sequence pattern transmitted from an optical transmitter, a symbol position of the reception signal, and generates an estimated symbol position, a delay unit configured to provide a delay difference between the first signal component and the second signal component, a control unit configured to set a plurality of symbol displacement amount candidates of displacement amounts for the estimated symbol position, causes the delay unit to generate a plurality of delay differences, and generates a channel estimation symbol position used for channel estimation, and an error rate calculation unit configured to calculate an error rate of the signal restored by an adaptive equalization unit.

Optical receiving device

A wiring inspection apparatus includes a first calculating unit, a second calculating unit, and an output unit. The first calculating unit calculates the number of components arranged along two sides, one of which extends in a first direction and the other one of which extends in a second direction, of a minimum rectangle including a transmission component and a reception component. The second calculating unit calculates the number of the components arranged along the two sides at a predetermined arrangement density of relay components. When the number of the relay components is greater than the number of the components calculated by the second calculating unit, the output unit outputs information indicating the presence of a wiring extending in a direction opposite to a direction from the transmission component to the reception component among wirings connecting the transmission component, the reception component, and the relay components.

Wiring inspection apparatus and wiring inspection method

A wiring inspection apparatus includes a dividing unit, a calculating unit, and an output unit. The dividing unit draws a boundary line in a predetermined area between a transmission component and a reception component, to divide the predetermined area into a first area containing the transmission component and a second area containing the reception component. The transmission component transmits a signal to the reception component via relay components. The calculating unit calculates a number of wirings that connect the components across the boundary line, based on positions of the transmission component, the reception component, and the relay components in the predetermined area. The output unit outputs information indicating the presence of a wiring extending in a direction opposite to a direction from the transmission component to the reception component, when the number of the wirings calculated by the calculating unit is equal to or greater than a predetermined value.

An arctangent calculation apparatus includes a phase angle memory unit in which a phase angle is stored in advance, the phase angle corresponding to a two-dimensional vector value corresponding to in a range of 0&#xb0; to substantially 22.5&#xb0;; a vector rotation unit that performs a vector rotation operation on a two-dimensional vector value corresponding to in a range of 0&#xb0; to 360&#xb0; and converts the two-dimensional vector value corresponding to in a range of 0&#xb0; to 360&#xb0; into a two-dimensional vector value corresponding to in a range of 0&#xb0; to substantially 2.5&#xb0;; an arctangent calculation unit that outputs, from the phase angle memory unit, a phase angle that corresponds to the two-dimensional vector value corresponding to in a range of 0&#xb0; to substantially 22.5&#xb0;; and a phase angle conversion unit that converts the phase angle into a phase angle in a range of 0&#xb0; to 360&#xb0;.

Apparatus and program for arctangent calculation

An optical amplification device is disclosed that performs feedback control to maintain an amplification gain to be a constant based on measured power of input light and power of output light. The device includes a feedback control coefficient switching unit configured to, when performing the feedback control on a difference from an object amplification gain, distinguish a state of increasing or decreasing the number of frequencies of the input light and a steady state by making comparison and determination whether an amplitude of at least one of the power of the input light and the power of the output light is in a predetermined range, and switch the feedback control coefficient. Therefore, it is possible to reduce variation of the power of the output light caused by noise in the steady state without affecting operations of increasing and decreasing a number of frequencies of a light signal.

Optical amplification device

An optical amplifier is provided with a controlling unit for controlling a gain of the optical amplifier based on input light power and output light power of the optical amplifier, as well as a gain control amount variable unit for changing the gain control amount of the optical amplifier by the controlling unit according to at least one of the input light power and the output light power. Thereby, optical communication, which can follow the change in the input power of the optical amplifier in high speed and also is stable, can be realized, without causing the occurrence of an oscillation phenomenon, the large size of the optical amplifier, and the increase in power consumption and heating.

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Atsugi, Japan

Masato Oota