Patents by Inventor Seiji Okamoto
Seiji Okamoto 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).
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Publication number: 20220416890Abstract: An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.Type: ApplicationFiled: December 16, 2019Publication date: December 29, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo SASAI, Fukutaro HAMAOKA, Masanori NAKAMURA, Seiji OKAMOTO
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Patent number: 11463169Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.Type: GrantFiled: January 15, 2020Date of Patent: October 4, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Horikoshi, Masanori Nakamura, Yoshiaki Kisaka, Seiji Okamoto, Fukutaro Hamaoka
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Publication number: 20220303003Abstract: A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an LO norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.Type: ApplicationFiled: September 17, 2019Publication date: September 22, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Seiji OKAMOTO, Hideki NISHIZAWA, Etsushi YAMAZAKI
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Patent number: 11444699Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps.Type: GrantFiled: January 15, 2020Date of Patent: September 13, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira Masuda, Fukutaro Hamaoka, Shuto Yamamoto, Seiji Okamoto, Kengo Horikoshi, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
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Publication number: 20220224415Abstract: An electric digital received signal obtained from a received optical signal is segmented into blocks of a certain length with an overlap of a length determined in advance with an adjacent block. Fourier transformation is performed for each of the blocks. The blocks subjected to the Fourier transformation are stored consecutively in time series, a coefficient determined based on a wavelength dispersion compensation amount according to one of frequency positions and a delay amount according to one of the frequency positions and one of time positions is applied to each of frequency component values included in a plurality of the stored blocks, and the blocks to which the coefficient has been applied and which are obtained by adding up the frequency component values to which the coefficient has been applied for each of the frequency positions are generated. Inverse Fourier transformation is performed on the generated blocks to which the coefficient has been applied.Type: ApplicationFiled: June 6, 2019Publication date: July 14, 2022Inventors: Masanori NAKAMURA, Seiji Okamoto, Kengo HORIKOSHI, Shuto YAMAMOTO, Takayuki KOBAYASHI, Yoshiaki KISAKA, Masahito TOMIZAWA
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Patent number: 11381317Abstract: An optical receiving device that divides receive signals obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands, matches timing of the receive signals along a time axis between the frequency bands resulting from the division, performs a combining process of combining the receive signals contained in the plurality of frequency bands, and compensates the receive signals for waveform distortion either before or after the combining process, includes: a first wavelength dispersion compensation unit adapted to compensate the receive signals for waveform distortion in each of the frequency bands resulting from the division; a first nonlinear compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and timed with each other in a time domain for a nonlinear optical effect; and a second wavelength dispersion compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and compensateType: GrantFiled: January 6, 2020Date of Patent: July 5, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji Okamoto, Yoshiaki Kisaka, Masanori Nakamura
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Patent number: 11349572Abstract: An optical communication system is provided in which a serial/parallel converting unit outputs bit sequences of sequence groups a number of which is determined by a logarithmic value and a bit sequence of a highest-order sequence group, a converting unit converts the bit sequence of the sequence group input to the converting unit into a bit sequence for which a probability of occurrence of 0 or a probability of occurrence of 1 is a predetermined probability of occurrence, a selecting unit acquires a bit sequence for which the probability of occurrence is converted by a converting unit higher in order than the converting unit for the selecting unit, and selects an order of output of a symbol to other selecting units in the sequence groups higher in order than the selecting unit in accordance with the acquired bit sequence, a multiplication unit multiplies a value representing the symbol selected by a highest-order selecting unit, by a number in accordance with the bit sequence of the highest order sequence groType: GrantFiled: May 8, 2019Date of Patent: May 31, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masanori Nakamura, Seiji Okamoto, Etsushi Yamazaki, Yoshiaki Kisaka
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Patent number: 11342990Abstract: A state estimating device includes a pre-processing unit and an estimating unit. The pre-processing unit acquires data representing at one or more of a phase of a signal transmitted from a transmission unit of a transmission device and received at a reception unit of another transmission device via a transmission path, a reception strength, a reception quality, a voltage after conversion into an electric signal, and a signal processing parameter used in reception processing, and processes the acquired data into feature data to be used for state estimation. The estimating unit estimates a state of the transmission path, an abnormal state of the transmission unit, or an abnormal state of the reception unit, on the basis of the feature data.Type: GrantFiled: February 13, 2019Date of Patent: May 24, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiki Kuwabara, Wataru Kawakami, Hideki Nishizawa, Seiji Okamoto, Akira Hirano, Shokei Kobayashi, Tetsuro Inui, Takuya Oda, Fumikazu Inuzuka, Takafumi Tanaka
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Publication number: 20220158731Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.Type: ApplicationFiled: January 15, 2020Publication date: May 19, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Yoshiaki KISAKA, Seiji OKAMOTO, Fukutaro HAMAOKA
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Publication number: 20220130361Abstract: A musical tone generating device includes: a nonvolatile storage device that stores musical tone waveform data; a volatile storage device; and a control means that, when a power supply is turned on, performs control to transfer musical tone waveform data to the volatile storage device from the nonvolatile storage device, in the case where an instruction to reproduce a musical tone is given, the control means to read musical tone waveform data from the volatile storage device, and in the case where an error in the read musical tone waveform data is detected, the control means to perform control to overwrite musical tone waveform data obtained by correcting the musical tone waveform data including the detected error to the volatile storage device or transfer normal musical tone waveform data corresponding to the musical tone waveform data including the detected error to the volatile storage device from the nonvolatile storage device.Type: ApplicationFiled: October 27, 2021Publication date: April 28, 2022Applicant: KABUSHIKI KAISHA KAWAI GAKKI SEISAKUSHOInventors: Seiji OKAMOTO, Tetsuya HIRANO
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Patent number: 11316588Abstract: Provided is a chromatic dispersion compensation method including: dividing a reception signal obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands; adjusting a timing on a time axis of the reception signal for each of the divided frequency bands; performing combination processing for combining the reception signals included in the plurality of frequency bands; performing chromatic dispersion compensation on the reception signal at any timing before or after the combination processing; selecting, before the combination processing, sections in which overlapping parts determined based on lengths of overlap parts are generated; outputting the reception signal for each of the selected sections as a division processing block; and removing the overlap parts from both ends of a processing block generated by combination of the division processing blocks in the combination processing so as to be continuous on a frequency axis.Type: GrantFiled: August 27, 2019Date of Patent: April 26, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kyo Minoguchi, Etsushi Yamazaki, Seiji Okamoto, Yoshiaki Kisaka
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Publication number: 20220114085Abstract: A digital signal processing device includes: a delay means that delays audio data in units of sampling periods; and a control means that writes audio data to a first buffer memory one word at a time in sequence at a sampling period, performs control to burst transfer burst length audio data to a DRAM from the first buffer memory, performs control to burst transfer the burst length audio data to a second buffer memory from the DRAM, and outputs audio data to the delay means from the second buffer memory one word at a time in sequence at the sampling period, in which a delay time of audio data output by the delay means is determined by a combination of a delay time of multiple sampling period units depending on a burst length of the DRAM and a delay time of a sampling period unit of the delay means.Type: ApplicationFiled: October 12, 2021Publication date: April 14, 2022Applicant: KABUSHIKI KAISHA KAWAI GAKKI SEISAKUSHOInventors: Seiji OKAMOTO, Tetsuya HIRANO
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Patent number: 11303359Abstract: There is provided a communication system, wherein: an optical transmission apparatus has: a first storage unit that stores amplitude distribution information, which is information representing a distribution of occurrence probabilities of symbols of an optical signal, in association with a modulation rate of an optical signal; a control unit that selects the modulation rate based on a signal band that is a band determined by the modulation rate and a device band that is a band in which a transmission path and the like allow passage of an optical signal, and controls an occurrence probability of a symbol of an optical signal based on the amplitude distribution information; and an optical transmitter that transmits an optical signal of a symbol of which the occurrence probability is controlled; and an optical reception apparatus has: an optical receiver that receives an optical signal of a symbol; a second storage unit that stores the amplitude distribution information in association with the modulation rate; aType: GrantFiled: July 2, 2019Date of Patent: April 12, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji Okamoto, Fukutaro Hamaoka, Masanori Nakamura, Yoshiaki Kisaka
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Publication number: 20220100458Abstract: A digital signal processing device includes a control unit that performs control to alternately burst transfer burst length audio data in a first half area of a first buffer memory and burst length audio data in a second half area of the first buffer memory to a DRAM, in which the control unit performs control to burst transfer the burst length audio data in the first half area of the first buffer memory to the DRAM while writing audio data one word at a time to the second half area of the first buffer memory in sequence and performs control to burst transfer the burst length audio data in the second half area of the first buffer memory to the DRAM while writing audio data one word at a time to the first half area of the first buffer memory in sequence.Type: ApplicationFiled: July 14, 2021Publication date: March 31, 2022Applicant: KABUSHIKI KAISHA KAWAI GAKKI SEISAKUSHOInventor: Seiji OKAMOTO
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Publication number: 20220094440Abstract: An optical receiving device that divides receive signals obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands, matches timing of the receive signals along a time axis between the frequency bands resulting from the division, performs a combining process of combining the receive signals contained in the plurality of frequency bands, and compensates the receive signals for waveform distortion either before or after the combining process, includes: a first wavelength dispersion compensation unit adapted to compensate the receive signals for waveform distortion in each of the frequency bands resulting from the division; a first nonlinear compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and timed with each other in a time domain for a nonlinear optical effect; and a second wavelength dispersion compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and compensateType: ApplicationFiled: January 6, 2020Publication date: March 24, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji OKAMOTO, Yoshiaki KISAKA, Masanori NAKAMURA
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Patent number: 11283528Abstract: A digital coherent receiver includes: an adaptive equalizer configured to execute, using a first tap coefficient, adaptive equalization processing on a digital signal that corresponds to a signal; a first coefficient updating unit configured to update the first tap coefficient based on the digital signal on which the adaptive equalization processing has not been executed, the digital signal on which the adaptive equalization processing has been executed, and a first step size; a second coefficient updating unit configured to update a second tap coefficient based on the digital signal on which the adaptive equalization processing has not been executed, the digital signal on which the adaptive equalization processing has been executed, and a second step size; and a control unit configured to detect a fluctuation speed of a state of polarization of the digital signal based on the second tap coefficient, and change the first tap coefficient to the updated second tap coefficient if it is determined that the fluctuType: GrantFiled: August 27, 2019Date of Patent: March 22, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira Masuda, Seiji Okamoto, Shuto Yamamoto, Fukutaro Hamaoka, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
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Publication number: 20220069921Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps.Type: ApplicationFiled: January 15, 2020Publication date: March 3, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira MASUDA, Fukutaro HAMAOKA, Shuto YAMAMOTO, Seiji OKAMOTO, Kengo HORIKOSHI, Masanori NAKAMURA, Asuka MATSUSHITA, Yoshiaki KISAKA
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Patent number: 11258512Abstract: A reception apparatus includes a dispersion compensation unit configured to acquire an electrical signal resulting from conversion of an optical signal and perform, on the electrical signal, dispersion compensation with a predetermined compensation amount, a clip rate measurement unit configured to measure a clip rate for the electrical signal subjected to the dispersion compensation, and a control unit configured to detect the compensation amount that minimizes the clip rate.Type: GrantFiled: May 8, 2019Date of Patent: February 22, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji Okamoto, Masanori Nakamura, Kengo Horikoshi
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Patent number: 11245487Abstract: An optical transmission system includes an optical transmitter, an optical receiver, and a control apparatus. The control apparatus repeatedly performs an adjustment process for adjusting power of an optical signal of a frequency band to be adjusted while switching the frequency band to be adjusted between at least two frequency bands including at least a frequency band where stimulated Raman scattering occurs among frequency bands that are multiplexed in a multiplexed optical signal transmitted by the optical transmission system. In the adjustment process, when power of an optical signal of the frequency band to be adjusted transmitted from the optical transmitter has been changed, the control apparatus determines the power of the optical signal of the frequency band to be adjusted on the basis of a signal quality measured by the optical receiver that has received the optical signal.Type: GrantFiled: May 20, 2019Date of Patent: February 8, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Fukutaro Hamaoka, Kyo Minoguchi, Seiji Okamoto, Yoshiaki Kisaka
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Publication number: 20220038180Abstract: Provided is a chromatic dispersion compensation method including: dividing a reception signal obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands; adjusting a timing on a time axis of the reception signal for each of the divided frequency bands; performing combination processing for combining the reception signals included in the plurality of frequency bands; performing chromatic dispersion compensation on the reception signal at any timing before or after the combination processing; selecting, before the combination processing, sections in which overlapping parts determined based on lengths of overlap parts are generated; outputting the reception signal for each of the selected sections as a division processing block; and removing the overlap parts from both ends of a processing block generated by combination of the division processing blocks in the combination processing so as to be continuous on a frequency axis.Type: ApplicationFiled: August 27, 2019Publication date: February 3, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kyo MINOGUCHI, Etsushi YAMAZAKI, Seiji OKAMOTO, Yoshiaki KISAKA