Patents by Inventor Hitoshi Takeshita
Hitoshi Takeshita 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).
-
Publication number: 20150289036Abstract: It is difficult to increase the number of inputs and outputs of an optical switch supporting CDC functions, therefore, an optical switch according to an exemplary aspect of the present invention includes a unit optical switch inputting n optical signals and outputting n optical signals; an optical splitter inputting a single optical signal, splitting the single optical signal into k optical signals, and outputting the k optical signals; and an optical selector inputting m optical signals and outputting a single optical signal, wherein the optical splitter includes m×n pieces, the unit optical switch includes m×k pieces, the optical selector includes n×k pieces, (k×(m×n)) outputs of the optical splitter correspond to (n×(m×k)) inputs of the unit optical switch, (n×(m×k)) outputs of the unit optical switch correspond to (m×(n×k)) inputs of the optical selector, and (n×m) optical signals inputted into the optical splitter are output through the (m×k) unit optical switch from the optical selector as (n×k) opticalType: ApplicationFiled: November 12, 2013Publication date: October 8, 2015Inventors: Hitoshi Takeshita, Ryuichi Ikematsu, Akio Tajima
-
Patent number: 8639114Abstract: In the optical communication device and the optical communication system using DPSK modulation whose cost is low, whose size is small and whose power consumption is low, the N:1 multiplexer 125 generates a serial signal by multiplexing a parallel signal coded by the DPSK modulation coding units 115˜117 bit by bit on a time division basis. The electric-phase modulation optical converter 127 converts a serial signal into a phase modulation light. The N-bit delay interferometer 132 executes DPSK decoding with respect to a phase modulation light by comparison with an N-bit preceding optical signal. The optical-electric signal converter 134 converts a decoded intensity modulation light into an electric signal. The N:1 demultiplexer 136 divides an electric signal converted by the optical-electric signal converter 134 into a number N of signals bit by bit on a time division basis.Type: GrantFiled: June 28, 2006Date of Patent: January 28, 2014Assignee: NEC CorporationInventors: Satomi Shioiri, Toshiharu Itou, Kiyoshi Fukuchi, Hitoshi Takeshita
-
Patent number: 8405511Abstract: An optical signal quality monitoring apparatus includes a trajectory length acquirer measuring a Stokes vector of an optical transmission signal over an optical signal modulation frequency band and acquiring the length of a trajectory in the optical signal modulation frequency band traced out on a Poincare sphere by the measured Stokes vector as the measurement value; a DGD acquirer acquiring a DGD value of the optical transmission signal the Stokes vector of which is measured by the trajectory length acquirer; and a quality value estimator estimating a quality value by using the length of the trajectory acquired by the trajectory length acquirer and the DGD value acquired by the DGD acquirer.Type: GrantFiled: March 31, 2009Date of Patent: March 26, 2013Assignee: NEC CorporationInventor: Hitoshi Takeshita
-
Patent number: 8175455Abstract: The present invention is intended to provide an optical transmission system which is applicable not only to a known signal but also to an unknown signal, and has a high reliability at a low cost. A branching device branches an optical transmission output of a transmitter, and transmits the branched signals through different optical transmission channels. A polarization mode dispersion monitor monitors the degree of polarization mode dispersion from the optical transmission channels at the receiving end. A switch control circuit and a switch select a signal which is less affected by a deterioration in quality due to polarization mode dispersion, and outputs the selected signal to receiver 8. In this way, the probability of a deterioration in the quality of a signal due to polarization mode dispersion can be reduced for a transmission signal.Type: GrantFiled: October 4, 2007Date of Patent: May 8, 2012Assignee: NEC CorporationInventors: Hitoshi Takeshita, Toshiharu Ito
-
Patent number: 8165477Abstract: The present invention provides a light receiving apparatus using the DQPSK demodulation method. The light receiving apparatus comprises: one Mach-Zehnder interferometer for branching a received light signal into light signals at two arms to allow the branched two light signals to interfere with each other; one balanced photoelectric converter for converting the two interfered light signals, by using the Mach-Zehnder interferometer, into an electric signal corresponding to a difference between light intensities of the two light signals; and a phase adjuster for dynamically shifting the phase of a light signal passed through one of the two arms at the Mach-Zehnder interferometer.Type: GrantFiled: December 6, 2007Date of Patent: April 24, 2012Assignee: NEC CorporationInventors: Satomi Shioiri, Kiyoshi Fukuchi, Toshiharu Ito, Hitoshi Takeshita
-
Publication number: 20100021169Abstract: The present invention is intended to provide an optical transmission system which is applicable not only to a known signal but also to an unknown signal, and has a high reliability at a low cost. A branching device branches an optical transmission output of a transmitter, and transmits the branched signals through different optical transmission channels. A polarization mode dispersion monitor monitors the degree of polarization mode dispersion from the optical transmission channels at the receiving end. A switch control circuit and a switch select a signal which is less affected by a deterioration in quality due to polarization mode dispersion, and outputs the selected signal to receiver 8. In this way, the probability of a deterioration in the quality of a signal due to polarization mode dispersion can be reduced for a transmission signal.Type: ApplicationFiled: October 4, 2007Publication date: January 28, 2010Inventors: Hitoshi Takeshita, Toshiharu Ito
-
Publication number: 20090267778Abstract: An optical signal quality monitoring apparatus includes a trajectory length acquirer measuring a Stokes vector of an optical transmission signal over an optical signal modulation frequency band and acquiring the length of a trajectory in the optical signal modulation frequency band traced out on a Poincare sphere by the measured Stokes vector as the measurement value; a DGD acquirer acquiring a DGD value of the optical transmission signal the Stokes vector of which is measured by the trajectory length acquirer; and a quality value estimator estimating a quality value by using the length of the trajectory acquired by the trajectory length acquirer and the DGD value acquired by the DGD acquirer.Type: ApplicationFiled: March 31, 2009Publication date: October 29, 2009Applicant: NEC CorporationInventor: Hitoshi Takeshita
-
Publication number: 20080232815Abstract: In the optical communication device and the optical communication system using DPSK modulation whose cost is low, whose size is small and whose power consumption is low, the N:1 multiplexer 125 generates a serial signal by multiplexing a parallel signal coded by the DPSK modulation coding units 115˜117 bit by bit on a time division basis. The electric-phase modulation optical converter 127 converts a serial signal into a phase modulation light. The N-bit delay interferometer 132 executes DPSK decoding with respect to a phase modulation light by comparison with an N-bit preceding optical signal. The optical-electric signal converter 134 converts a decoded intensity modulation light into an electric signal. The N:1 demultiplexer 136 divides an electric signal converted by the optical-electric signal converter 134 into a number N of signals bit by bit on a time division basis.Type: ApplicationFiled: June 28, 2006Publication date: September 25, 2008Applicant: NEC CorporationInventors: Satomi Shioiri, Toshiharu Itou, Kiyoshi Fukuchi, Hitoshi Takeshita
-
Publication number: 20080183062Abstract: Provided is a method of distinguishing among Stanford type A acute aortic dissection, Stanford type B acute aortic dissection, and acute myocardial infarction, which are mutually similar in terms of clinical symptoms, and a kit for the distinguishment. Specifically, provided is a method of distinguishing among Stanford type A acute aortic dissection, Stanford type B acute aortic dissection, and acute myocardial infarction, which comprises detecting both D-dimer and H-FABP in blood separated from a person suspected of having acute aortic dissection and suspected of having acute myocardial infarction, and establishing the diagnosis on the basis of the concentrations detected, and a kit for the distinguishment.Type: ApplicationFiled: February 23, 2005Publication date: July 31, 2008Inventors: Hiroshi Hazui, Masayoshi Nishimoto, Hitoshi Takeshita, Yasuhiko Ohkaru
-
Publication number: 20080181616Abstract: A wavelength dispersion compensation control device includes an error correction circuit for correcting a code error of a signal from an optical transmission line, a variable wavelength dispersion compensator for changing wavelength dispersion characteristics based on this error correction information and performing a dispersion compensation of the optical transmission line, and a control circuit for performing a control of the variable wavelength dispersion compensator based on the number of error corrections that is the error correction information so that this error correction number becomes the minimum, wherein the control circuit, when scanning the dispersion at predetermined step widths in a variable range of the variable wavelength dispersion compensator, increases a dispersion setting value at the variable wavelength dispersion compensator while the step width is set as ?D1 when an error correction success and failure information that is the error correction information is failure, and increases the dType: ApplicationFiled: October 29, 2007Publication date: July 31, 2008Applicant: NEC CORPORATIONInventor: Hitoshi Takeshita
-
Publication number: 20080152359Abstract: The present invention provides a light receiving apparatus using the DQPSK demodulation method. The light receiving apparatus comprises: one Mach-Zehnder interferometer for branching a received light signal into light signals at two arms to allow the branched two light signals to interfere with each other; one balanced photoelectric converter for converting the two interfered light signals, by using the Mach-Zehnder interferometer, into an electric signal corresponding to a difference between light intensities of the two light signals; and a phase adjuster for dynamically shifting the phase of a light signal passed through one of the two arms at the Mach-Zehnder interferometer.Type: ApplicationFiled: December 6, 2007Publication date: June 26, 2008Applicant: NEC CORPORATIONInventors: Satomi SHIOIRI, Kiyoshi Fukuchi, Toshiharu Ito, Hitoshi Takeshita
-
Patent number: 7340187Abstract: In an optical signal monitoring method in wavelength multiplexing and an optical network, an area corresponding to a characteristic pattern of an eye pattern of an optical signal to be monitored, which characterizes a deterioration, is extracted from a database storing a map which associates a quality deterioration factor and deterioration amount of the optical signal with the characteristic pattern of the area of the eye pattern of the optical signal. The extracted pattern is collated with the map stored in the database to monitor the quality deterioration factor and deterioration amount of the optical signal, an occurrence time of a deterioration, duration of a deterioration, a deterioration occurrence cycle, and a deterioration duration cycle. An optical signal monitoring apparatus is also disclosed.Type: GrantFiled: December 22, 2003Date of Patent: March 4, 2008Assignee: NEC CorporationInventor: Hitoshi Takeshita
-
Patent number: 7280756Abstract: A main optical signal is wavelength-multiplexed with an optical identifier which is different in wavelength from this main optical signal, before a wavelength-demultiplexing is take place at a desired point so as to isolate the optical identifier from the main optical signal for the purpose of monitoring establishment of correct or incorrect transmission route between transmission and receiving sides based on the detected optical identifier with reference to the stored corresponding data to the relationship between the main optical signal and the optical identifier which belongs to the main optical signal, wherein the monitoring is made without any photoelectric conversion of the main optical signal and any deterioration in quality of the main optical signal.Type: GrantFiled: July 7, 2003Date of Patent: October 9, 2007Assignee: NEC CorporationInventor: Hitoshi Takeshita
-
Patent number: 7280470Abstract: Multiple working paths are established on each working rings and multiple protection paths are established on each of multiple protection rings. A working path on a first working ring spans across first and second nodes for signal transmission in a first direction of the ring, and a working path on a second working ring spans across the first and second nodes for signal transmission in a second, opposite direction of the ring. A protection path on a first protection ring spans across the first and second nodes for signal transmission in said second direction, and a protection path on a second protection ring spans across the first and second nodes for signal transmission in said first direction. The first and second nodes normally use the working paths, respectively. When one of the working paths fails, the first and second nodes use a corresponding protection path.Type: GrantFiled: September 3, 2003Date of Patent: October 9, 2007Assignee: NEC CorporationInventors: Tatsuya Shiragaki, Naoya Henmi, Makoto Nishio, Hitoshi Takeshita, Hirofumi Shimomura
-
Patent number: 6895183Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=1˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.Type: GrantFiled: April 30, 2002Date of Patent: May 17, 2005Assignee: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi, Hitoshi Takeshita
-
Patent number: 6771907Abstract: An optical ring system having: a wavelength demultiplexer to which wavelength-multiplexed optical signal to be sent through an optical fiber from a previous node of multiple nodes is input and in which optical signal with each wavelength assigned to itself is demultiplexed; an optical ring device which is disposed in a predetermined node of the multiple nodes to the each wavelength assigned and which is composed of a failure existence judging part which terminates an overhead of each optical signal with a wavelength demultiplexed by the wavelength demultiplexer and judges whether a failure occurs in regard to a wavelength in a previous section through which optical signal with the assigned wavelength is sent, and a switching part which, when the failure existence judging means determines the occurrence of failure, selects a path that allows optical signal with the wavelength to be transmitted to the previous node while avoiding the previous section incurring the failure; and a wavelength multiplexer which mulType: GrantFiled: May 24, 2000Date of Patent: August 3, 2004Assignee: NEC CorporationInventors: Yuuki Yoshifuji, Shuichi Iida, Takashi Yamazaki, Youko Nakabayashi, Shinya Nakamura, Kimio Ozawa, Naoki Ando, Hitoshi Kikuchi, Tukasa Haga, Hiromitu Watanabe, Minoru Shinta, Hitoshi Takeshita, Shinobu Sasaki, Ryou Yamada, Naoya Henmi
-
Publication number: 20040131355Abstract: In an optical signal monitoring method in wavelength multiplexing and an optical network, an area corresponding to a characteristic pattern of an eye pattern of an optical signal to be monitored, which characterizes a deterioration, is extracted from a database storing a map which associates a quality deterioration factor and deterioration amount of the optical signal with the characteristic pattern of the area of the eye pattern of the optical signal. The extracted pattern is collated with the map stored in the database to monitor the quality deterioration factor and deterioration amount of the optical signal, an occurrence time of a deterioration, duration of a deterioration, a deterioration occurrence cycle, and a deterioration duration cycle. An optical signal monitoring apparatus is also disclosed.Type: ApplicationFiled: December 22, 2003Publication date: July 8, 2004Applicant: NEC CORPORATIONInventor: Hitoshi Takeshita
-
Publication number: 20040057375Abstract: In a ring topology network, a number of nodes interconnect transmission links to form first and second working rings and first and second optical protection rings in a ring topology. Multiple working paths are established on each working ring and multiple protection paths are established on each protection ring corresponding to the working paths. A first working path spans across first and second nodes for transmission of a signal in a first direction of the ring topology, and a second working path of the second working ring spans across the first and second nodes for transmission of a signal in a second direction of the ring topology opposite to the first direction. A first protection path on the first protection ring spans across the first and second nodes for transmission of a signal in the second direction of the ring topology, and a second protection path of the second protection ring spans across the first and second nodes for transmission of a signal in the first direction of the ring topology.Type: ApplicationFiled: September 3, 2003Publication date: March 25, 2004Applicant: NEC CorporationInventors: Tatsuya Shiragaki, Naoya Henmi, Makoto Nishio, Hitoshi Takeshita, Hirofumi Shimomura
-
Publication number: 20040005150Abstract: A main optical signal is wavelength-multiplexed with an optical identifier which is different in wavelength from this main optical signal, before a wavelength-demultiplexing is take place at a desired point so as to isolate the optical identifier from the main optical signal for the purpose of monitoring establishment of correct or incorrect transmission route between transmission and receiving sides based on the detected optical identifier with reference to the stored corresponding data to the relationship between the main optical signal and the optical identifier which belongs to the main optical signal, wherein the monitoring is made without any photoelectric conversion of the main optical signal and any deterioration in quality of the main optical signal.Type: ApplicationFiled: July 7, 2003Publication date: January 8, 2004Applicant: NEC CorporationInventor: Hitoshi Takeshita
-
Patent number: 6657952Abstract: In a ring topology network, a number of nodes interconnect transmission links to form first and second working rings and first and second optical protection rings in a ring topology. Multiple working paths are established on each working ring and multiple protection paths are established on each protection ring corresponding to the working paths. A first working path spans across first and second nodes for transmission of a signal in a first direction of the ring topology, and a second working path of the second working rings spans across the first and second nodes for transmission of a signal in a second direction of the ring topology opposite to the first direction. A first protection path on the first protection ring spans across the first and second nodes for transmission of a signal in the second direction of the ring topology, and a second protection path of the second protection ring spans across the first and second nodes for transmission of a signal in the first direction of the ring topology.Type: GrantFiled: November 27, 1998Date of Patent: December 2, 2003Assignee: NEC CorporationInventors: Tatsuya Shiragaki, Naoya Henmi, Makoto Nishio, Hitoshi Takeshita, Hirofumi Shimomura