Patents by Inventor Kazuo Shirakawa

Kazuo Shirakawa 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).

  • Patent number: 10852410
    Abstract: A receiving circuit uses a weight set by calibration to weight signals incident to receiving elements. A storing unit stores a measured value of a mode vector reflecting characteristics of the receiving circuit in an error-free state of the weight for the receiving circuit characteristics and further correlates and stores an incident signal angle estimated by an estimating unit, and for the error-free state, a calculation result of an evaluation value by an evaluation function capable of calculating the evaluation value, which varies according to the incident signal angle and error. A detecting unit calculates the evaluation value based on the stored measured value of the mode vector and the evaluation function and detects an occurrence of the error based on comparison of the calculated evaluation value and the stored evaluation value, when the estimated incident signal angle corresponds to a value close to the stored incident signal angle.
    Type: Grant
    Filed: October 8, 2015
    Date of Patent: December 1, 2020
    Assignee: DENSO TEN LIMITED
    Inventors: Kazuo Shirakawa, Yasuhiro Kurono
  • Patent number: 9645230
    Abstract: A detection and ranging apparatus includes a probe signal generating unit that generates a probe signal according to a first modulation method, a transmitting unit that transmits the generated probe signal, a receiving unit that receives a signal including at least one of a reflection signal and an interference signal according to a second modulation method, a demodulating unit that demodulates the reception signal according to a method corresponding to at least one of the first modulation method and the second modulation method, an interference signal detecting unit that detects the interference signal from the demodulated signal, an interference signal identifying unit that identifies specifications and a delay amount of the interference signal from the demodulated signal, and an interference signal removing unit that removes the interference signal within the reception signal by using the identified specifications and the identified delay amount of the interference signal.
    Type: Grant
    Filed: August 20, 2014
    Date of Patent: May 9, 2017
    Assignee: FUJITSU LIMITED
    Inventor: Kazuo Shirakawa
  • Patent number: 9575170
    Abstract: In an in-vehicle radar device, as a vertical azimuth which is an azimuth of a target in a direction perpendicular to a ground surface, a real image vertical azimuth which is an azimuth of a real image existing above ground is calculated from a reflected wave generated when a transmission signal transmitted from a transmission antenna is reflected from the target, and a virtual image vertical azimuth which is an azimuth of a virtual image existing underground is calculated from a reflected wave generated when the transmission signal transmitted from the transmission antenna is reflected from the target and reflected again from the ground surface. Next, in the in-vehicle radar device, an angle difference between the real image vertical azimuth and the virtual image vertical azimuth is calculated, and a height of the target from the ground surface is calculated using the calculated angle difference.
    Type: Grant
    Filed: September 3, 2013
    Date of Patent: February 21, 2017
    Assignees: FUJITSU TEN LIMITED, FUJITSU LIMITED
    Inventors: Yasuhiro Kurono, Kazuo Shirakawa, Yoji Ohashi
  • Patent number: 9507018
    Abstract: An apparatus includes a first array including sensors; a second array including sensors that are not collinear with the sensors of the first array except for a sensor that defines the origin of a spatial phase; and a signal processing unit that generates covariance matrices including a first covariance matrix and a second covariance matrix based on reflected waves received by the first and second arrays from targets, estimates first angles of the targets based on the first covariance matrix, reproduces an angle matrix based on the estimated first angles, performs triangular decomposition on the product of a generalized inverse matrix of the angle matrix and the second covariance matrix to obtain a matrix, constructs a similarity transformation problem from submatrices of the obtained matrix, and estimates second angles of the targets based on the estimated first angles and solutions of the similarity transformation problem.
    Type: Grant
    Filed: April 2, 2013
    Date of Patent: November 29, 2016
    Assignee: FUJITSU LIMITED
    Inventor: Kazuo Shirakawa
  • Publication number: 20160103207
    Abstract: A receiving circuit uses a weight set by calibration to weight signals incident to receiving elements. A storing unit stores a measured value of a mode vector reflecting characteristics of the receiving circuit in an error-free state of the weight for the receiving circuit characteristics and further correlates and stores an incident signal angle estimated by an estimating unit, and for the error-free state, a calculation result of an evaluation value by an evaluation function capable of calculating the evaluation value, which varies according to the incident signal angle and error. A detecting unit calculates the evaluation value based on the stored measured value of the mode vector and the evaluation function and detects an occurrence of the error based on comparison of the calculated evaluation value and the stored evaluation value, when the estimated incident signal angle corresponds to a value close to the stored incident signal angle.
    Type: Application
    Filed: October 8, 2015
    Publication date: April 14, 2016
    Inventors: Kazuo SHIRAKAWA, Yasuhiro KURONO
  • Patent number: 9128171
    Abstract: A detection and ranging system includes: a signal generator configured to generate M probe signals having different carrier frequencies; M transmitting elements configured to transmit the M probe signals; N receiving elements configured to receive an echo signal from a target; N demodulators provided for the N receiving elements, each of the demodulators being configured to generate a demodulated echo signal by demodulating an echo signal received by a corresponding one of the receiving elements by using at least one of the M probe signals, and to generate M sets of data signals corresponding to the M probe signals by filtering the demodulated echo signal in a frequency domain; and a signal processor configured to detect the target according to M×N sets of data signals generated by the N demodulators.
    Type: Grant
    Filed: August 1, 2012
    Date of Patent: September 8, 2015
    Assignee: FUJITSU LIMITED
    Inventors: Kazuo Shirakawa, Yoji Ohashi
  • Patent number: 9091758
    Abstract: A detection and ranging system includes: M transmitting sensor elements configured to transmit a probe signal; N receiving sensor elements configured to receive an echo signal generated upon reflection of the probe signal from a target; a matrix generator configured to generate a third matrix by multiplying a first matrix by a second matrix, the first matrix including as diagonal components L received signals obtained from an effective receiving sensor array formed by synthesizing the M transmitting sensor elements and the N receiving sensor elements, the second matrix being formed of P L-dimensional vectors that are linearly independent of each other; and an estimator configured to estimate a direction of arrival of the echo signal from the target according to a pseudo covariance matrix generated by multiplying the third matrix by Hermitian conjugate transposition of the third matrix.
    Type: Grant
    Filed: November 19, 2012
    Date of Patent: July 28, 2015
    Assignees: FUJITSU LIMITED, FUJITSU TEN LIMITED
    Inventors: Kazuo Shirakawa, Yasuhiro Kurono
  • Publication number: 20150070204
    Abstract: A detection and ranging apparatus includes a probe signal generating unit that generates a probe signal according to a first modulation method, a transmitting unit that transmits the generated probe signal, a receiving unit that receives a signal including at least one of a reflection signal and an interference signal according to a second modulation method, a demodulating unit that demodulates the reception signal according to a method corresponding to at least one of the first modulation method and the second modulation method, an interference signal detecting unit that detects the interference signal from the demodulated signal, an interference signal identifying unit that identifies specifications and a delay amount of the interference signal from the demodulated signal, and an interference signal removing unit that removes the interference signal within the reception signal by using the identified specifications and the identified delay amount of the interference signal.
    Type: Application
    Filed: August 20, 2014
    Publication date: March 12, 2015
    Inventor: Kazuo Shirakawa
  • Patent number: 8928522
    Abstract: The conventional ESPRIT method is accompanied by the problem of very long signal processing time. The radar device of the invention includes a signal vector-forming unit for forming signal vectors based on waves reflected from an object and received by using a plurality of receiving antennas; a submatrix-forming unit for forming submatrices based on the signal vectors; a regular matrix operation unit for calculating a regular matrix from the submatrices; an eigenvalue decomposition unit for calculating an eigenvalue of the regular matrix; and an angle calculation unit for calculating an angle at where the object is present from the eigenvalue.
    Type: Grant
    Filed: November 4, 2011
    Date of Patent: January 6, 2015
    Assignees: Fujitsu Ten Limited, Fujitsu Limited
    Inventors: Yasuhiro Kurono, Kazuo Shirakawa
  • Patent number: 8816898
    Abstract: A radar apparatus includes: an array antenna having antenna elements having function of a transmission antenna and a reception antenna and receiving an echo signal which is a reflection of a probe signal from a target, the probe signal being radiated from the antenna elements; a converter for converting the echo signal to a baseband signal; a signal synthesizing unit which generates a synthesized baseband signal vector on the basis of aperture synthesis of the baseband signal generated from a combination of the antenna elements giving an equal spatial phase; a correction data acquiring unit which acquires correction data on the basis of coefficients of terms of a synthesized array polynomial; a correction processing unit which corrects the synthesized baseband signal vector on the basis of the correction data; and an estimating unit which performs angle estimation on the basis of the synthesized baseband signal vector.
    Type: Grant
    Filed: April 27, 2011
    Date of Patent: August 26, 2014
    Assignee: Fujitsu Limited
    Inventor: Kazuo Shirakawa
  • Patent number: 8742980
    Abstract: A radar device that detects a target includes two or more transmitting antennas and two or more receiving antennas, including a combination of two or more transmitting antennas and receiving antennas that form two or more reference paths at which spatial phases become identical; an envelope detection unit that acquires an envelope of a reception signal received by the receiving antenna in each of the reference paths; a determination unit that decides a phase correction amount between the reference paths from a delay amount that yields a minimum value of an integrated distance between envelopes of the reception signals of the reference paths; and a correction unit that aligns phases of all reception signals received by the two or more receiving antennas, using the decided phase correction amount.
    Type: Grant
    Filed: December 19, 2011
    Date of Patent: June 3, 2014
    Assignee: Fujitsu Limited
    Inventor: Kazuo Shirakawa
  • Publication number: 20140145872
    Abstract: A parameter changer changes the parameter of the complementary code input from a multiplexer. A separator separates the time-multiplexed complementary code of which parameter has been changed into the code sequences at the even numbers of the time slots and the code sequences at the odd numbers of the time slots. A demodulator demodulates the received signals using the parameter-changed complementary code in order to obtain the demodulated signal. An interference identifying unit identifies the interference signal included in the received signals using the demodulated signal from the demodulator.
    Type: Application
    Filed: September 25, 2013
    Publication date: May 29, 2014
    Applicant: FUJITSU LIMITED
    Inventor: Kazuo SHIRAKAWA
  • Publication number: 20140062762
    Abstract: In an in-vehicle radar device, as a vertical azimuth which is an azimuth of a target in a direction perpendicular to a ground surface, a real image vertical azimuth which is an azimuth of a real image existing above ground is calculated from a reflected wave generated when a transmission signal transmitted from a transmission antenna reflected from the target, and a virtual image vertical azimuth which is an azimuth of a virtual image existing underground is calculated from a reflected wave generated when the transmission signal transmitted from the transmission antenna is reflected from the target and reflected again from the ground surface. Next, in the in-vehicle radar device, an angle difference between the real image vertical azimuth and the virtual image vertical azimuth which are calculated is calculated, and a height of the target from the ground surface is calculated using the calculated angle difference.
    Type: Application
    Filed: September 3, 2013
    Publication date: March 6, 2014
    Applicants: FUJITSU LIMITED, FUJITSU TEN LIMITED
    Inventors: Yasuhiro KURONO, Kazuo SHIRAKAWA, Yoji OHASHI
  • Patent number: 8587470
    Abstract: Provided is a radar apparatus including an envelope detector unit that acquires an envelope component of a signal transmitted from a receiving antenna in at least one combination of a plurality of combinations of transmitting antennas and receiving antennas whose spatial phases become equal to each other in the array antenna; a determination unit that determines an amount of compensation in the at least one combination based on the envelope component acquired by the envelope detector unit; and a compensator unit that compensates a phase of a signal transmitted from each of the receiving antennas before aperture synthesis by using the amount of compensation determined by the determination unit, or compensates a phase of a signal radiated from the transmitting antenna in another combination.
    Type: Grant
    Filed: March 2, 2011
    Date of Patent: November 19, 2013
    Assignee: Fujitsu Limited
    Inventor: Kazuo Shirakawa
  • Publication number: 20130300596
    Abstract: An apparatus includes a first array including sensors; a second array including sensors that are not collinear with the sensors of the first array except for a sensor that defines the origin of a spatial phase; and a signal processing unit that generates covariance matrices including a first covariance matrix and a second covariance matrix based on reflected waves received by the first and second arrays from targets, estimates first angles of the targets based on the first covariance matrix, reproduces an angle matrix based on the estimated first angles, performs triangular decomposition on the product of a generalized inverse matrix of the angle matrix and the second covariance matrix to obtain a matrix, constructs a similarity transformation problem from submatrices of the obtained matrix, and estimates second angles of the targets based on the estimated first angles and solutions of the similarity transformation problem.
    Type: Application
    Filed: April 2, 2013
    Publication date: November 14, 2013
    Applicant: FUJITSU LIMITED
    Inventor: Kazuo SHIRAKAWA
  • Patent number: 8581747
    Abstract: Disclosed is a pedestrian support system that supports the movement of a pedestrian through the use of tags. This pedestrian support system comprises: a plurality of tags having an information storage unit and that are placed on a cable that extends over a traveled path; a guide device that is held by a pedestrian that is traveling along a sidewalk and that is capable of non-contact communication with the tags, and a central control device, comprising a database in which tag map information is recorded, that uses that tag map information to creates path information having tag IDs that are in the order of tags that are located along a path from a starting location to a destination location and directly or indirectly sets that path information in the guide device.
    Type: Grant
    Filed: September 10, 2009
    Date of Patent: November 12, 2013
    Assignee: Fujitsu Limited
    Inventor: Kazuo Shirakawa
  • Publication number: 20130069818
    Abstract: A detection and ranging system includes: a signal generator configured to generate M probe signals having different carrier frequencies; M transmitting elements configured to transmit the M probe signals; N receiving elements configured to receive an echo signal from a target; N demodulators provided for the N receiving elements, each of the demodulators being configured to generate a demodulated echo signal by demodulating an echo signal received by a corresponding one of the receiving elements by using at least one of the M probe signals, and to generate M sets of data signals corresponding to the M probe signals by filtering the modulated echo signal in a frequency domain; and a signal processor configured to detect the target according to M×N sets of data signals generated by the N demodulators.
    Type: Application
    Filed: August 1, 2012
    Publication date: March 21, 2013
    Applicant: FUJITSU LIMITED
    Inventors: Kazuo SHIRAKAWA, Yoji OHASHI
  • Publication number: 20120200446
    Abstract: A radar device that detects a target includes two or more transmitting antennas and two or more receiving antennas, including a combination of two or more transmitting antennas and receiving antennas that form two or more reference paths at which spatial phases become identical; an envelope detection unit that acquires an envelope of a reception signal received by the receiving antenna in each of the reference paths; a determination unit that decides a phase correction amount between the reference paths from a delay amount that yields a minimum value of an integrated distance between envelopes of the reception signals of the reference paths; and a correction unit that aligns phases of all reception signals received by the two or more receiving antennas, using the decided phase correction amount.
    Type: Application
    Filed: December 19, 2011
    Publication date: August 9, 2012
    Applicant: FUJITSU LIMITED
    Inventor: Kazuo SHIRAKAWA
  • Patent number: 8203485
    Abstract: A method includes generating a correlation vector of baseband-signal vectors based upon signals received from a plurality of sensor devices, generating a generalized Hankel matrix R representing a covariance matrix to which a spatial averaging is applied based upon the correlation vector, generating a kernel matrix ?1, which is a projection matrix onto noise subspace, by performing linear operation using submatrices R1 and R2 of the generalized Hankel matrix R, generating a kernel matrix ?2, which is orthogonal with the kernel matrix ?1, and estimating a direction of arrival of a signal based upon the kernel matrices ?1 and ?2.
    Type: Grant
    Filed: August 30, 2010
    Date of Patent: June 19, 2012
    Assignee: Fujitsu Limited
    Inventor: Kazuo Shirakawa
  • Publication number: 20120112954
    Abstract: The conventional ESPRIT method is accompanied by the problem of very long signal processing time. The radar device of the invention includes a signal vector-forming unit for forming signal vectors based on waves reflected from an object and received by using a plurality of receiving antennas; a submatrix-forming unit for forming submatrices based on the signal vectors; a regular matrix operation unit for calculating a regular matrix from the submatrices; an eigenvalue decomposition unit for calculating an eigenvalue of the regular matrix; and an angle calculation unit for calculating an angle at where the object is present from the eigenvalue.
    Type: Application
    Filed: November 4, 2011
    Publication date: May 10, 2012
    Applicants: FUJITSU LIMITED, FUJITSU TEN LIMITED
    Inventors: Yasuhiro KURONO, Kazuo SHIRAKAWA