公开(公告)号：US20250096919A1

公开(公告)日：2025-03-20

申请号：US18727823

申请日：2022-09-28

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akira KAWAI ,  Masanori NAKAMURA ,  Takayuki KOBAYASHI ,  Yutaka MIYAMOTO

IPC: H04J14/02 ,  H04J14/06

Abstract: A characteristic measurement device that measures a characteristic between lanes of a transmitter and a receiver connected via an optical fiber transmission path, the characteristic measurement device including an adaptive equalization unit that uses a polarization multiplexed reception signal and a phase conjugate signal of the polarization multiplexed reception signal or a plurality of signals mathematically equivalent to the reception signal and the phase conjugate signal of the reception signal as input signals and performs equalization processing on the input signals, and a characteristic function derivation unit that calculates a first inverse characteristic representing an inverse characteristic of the transmitter and a second inverse characteristic representing an inverse characteristic of the receiver on the basis of a filter coefficient obtained at the time of the equalization processing performed by the adaptive equalization unit and a frequency offset.

公开(公告)号：US20240413922A1

公开(公告)日：2024-12-12

申请号：US18695580

申请日：2021-09-29

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akira KAWAI ,  Takayuki KOBAYASHI ,  Masanori NAKAMURA ,  Shimpei SHIMIZU ,  Yutaka MIYAMOTO

IPC: H04J14/04 ,  H04B10/2581 ,  H04B10/516

Abstract: One aspect of the present invention is an optical transmission system including a transmitter connected to a transmission line having M spatial channels, and a receiver that receives a signal transmitted from the transmitter via the transmission line, wherein the transmitter includes: an allocator that allocates a transmission bit string transmitted to the transmission line into a bit string serving as a basic signal and a bit string serving as spatial channel information; a generator that generates N (M>N) signals from the bit string serving as the basic signal allocated by the allocator; and a selector that selects N spatial channels, through which the N signals generated by the generator are transmitted, from the M spatial channels on the basis of the bit string serving as the spatial channel information allocated by the allocator.

公开(公告)号：US20240259095A1

公开(公告)日：2024-08-01

申请号：US18290350

申请日：2021-05-18

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akira KAWAI ,  Takayuki KOBAYASHI ,  Masanori NAKAMURA ,  Shimpei SHIMIZU ,  Yutaka MIYAMOTO

IPC: H04B10/079

CPC classification number: H04B10/0795

Abstract: A waveguide estimation device includes: a time window processing unit that multiplies time-series tap coefficients of an adaptive filter by a time window function; and an estimation unit that estimates at least one of a differential group delay in a frequency series or a time series and a polarization dependent loss in a frequency series or a time series based on the time-series tap coefficients in a time window. The estimation unit may estimate at least one of the differential group delay in a frequency series or a time series and the polarization dependent loss in a frequency series or a time series based on a tap coefficient exceeding a lower limit threshold value or falling below an upper limit threshold value among the time-series tap coefficients in a time window. The estimation unit may estimate the average value of the differential group delays in a frequency series or a time series. The time window processing unit may determine the length of the time window based on a constant multiple of the average value.