Patents by Inventor Hans Hellsten

Hans Hellsten 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: 20200408896
    Abstract: A method for detecting a horizontally buried linear object is provided, the horizontally buried linear object having a longitudinal extension. The method comprises moving, with a flying platform comprising a radar for synthetic aperture radar, SAR, vertical imaging, along a trajectory corresponding to a synthetic aperture. The method further comprises transmitting and receiving radar signals while moving along the trajectory corresponding to the synthetic aperture. The method also comprises forming a SAR image based on collected data representing radar signal reflections received from the ground. The method additionally comprises detecting one or more features in the formed SAR image relating to the horizontally buried linear object. Said trajectory is oriented in a direction substantially perpendicular to an expected orientation of the longitudinal extension of the horizontally buried object and traversing the horizontally buried object.
    Type: Application
    Filed: March 8, 2019
    Publication date: December 31, 2020
    Applicant: SAAB AB
    Inventor: Hans HELLSTEN
  • Patent number: 10788587
    Abstract: The present invention relates to a method for determining a synthetic aperture of a synthetic aperture radar, SAR, system using information from a global navigation satellite system, GNSS, which includes a plurality of satellites each transmitting a radio frequency signal comprising a unique pseudo random number, PRN.
    Type: Grant
    Filed: September 19, 2018
    Date of Patent: September 29, 2020
    Assignee: SAAB AB
    Inventors: Patrik Dammert, Hans Hellsten
  • Patent number: 10746862
    Abstract: The present invention relates to a method for a continuous arbitrary waveform radar configured for transmitting and receiving signals over a selected communication band. The method comprises: generating the radar transmit signal with a waveform having a non-monotonic frequency change, modifying the waveform to obtain at least one spectral notch and isolating reception and transmission by cancellation. Each spectral notch at a selectable frequency with a selectable bandwidth, and the waveform is modified to maintain the spectral density of the transmit radar signal.
    Type: Grant
    Filed: February 5, 2018
    Date of Patent: August 18, 2020
    Assignee: SAAB AB
    Inventors: Patrik Dammert, Hans Hellsten
  • Publication number: 20200225360
    Abstract: The present invention relates to a method for determining a synthetic aperture of a synthetic aperture radar, SAR, system using information from a global navigation satellite system, GNSS, which includes a plurality of satellites each transmitting a radio frequency signal comprising a unique pseudo random number, PRN.
    Type: Application
    Filed: September 19, 2018
    Publication date: July 16, 2020
    Inventors: Patrik DAMMERT, Hans HELLSTEN
  • Patent number: 10571560
    Abstract: A method and a device for detecting at least one target in an image, wherein the image comprises a set of pixels with a magnitude assigned to each pixel is provided. The method comprises an iterative process until the K+1th target does not show a probability increase above a predetermined threshold value. The method is performed by creating a candidate free image, calculating, for the candidate free image, the probability of there being a target at each pixel, by using Bayes theorem, determining a location of the candidate target K+1 in the image, determining the probability that there is a target at the determined location, by determining the calculated probability of there being a target at the determined location. By performing the above, the most probable locations for targets in the image are located together with the probability that the location holds a true target.
    Type: Grant
    Filed: September 21, 2015
    Date of Patent: February 25, 2020
    Assignee: SAAB AB
    Inventor: Hans Hellsten
  • Publication number: 20190391246
    Abstract: The present invention relates to a method for a continuous arbitrary waveform radar configured for transmitting and receiving signals over a selected communication band. The method comprises: generating the radar transmit signal with a waveform having a non-monotonic frequency change, modifying the waveform to obtain at least one spectral notch and isolating reception and transmission by cancellation. Each spectral notch at a selectable frequency with a selectable bandwidth, and the waveform is modified to maintain the spectral density of the transmit radar signal.
    Type: Application
    Filed: February 5, 2018
    Publication date: December 26, 2019
    Inventors: Patrik DAMMERT, Hans HELLSTEN
  • Patent number: 10416303
    Abstract: A method and system for obtaining SAR images with reduced or eliminated surface clutter to detect subsurface targets, the method comprising the following steps:—selecting a first frequency and an incidence angle for the radar signal such that the ratio of surface backscattering to subsurface target backscattering is significantly larger for vertical polarization than for horizontal—obtaining vertically and horizontally polarized SAR images based on the same SAR path exploiting the selected first frequency and viewing angle—weighting and differencing the vertically and horizontally polarized SAR images so that the surface backscattering completely cancels between the two images and only the combination of the target backscattering components remains.
    Type: Grant
    Filed: November 7, 2016
    Date of Patent: September 17, 2019
    Assignee: SAAB AB
    Inventor: Hans Hellsten
  • Publication number: 20180267163
    Abstract: A method and a device for detecting at least one target in an image, wherein the image comprises a set of pixels with a magnitude assigned to each pixel is provided. The method comprises an iterative process until the K+1th target does not show a probability increase above a predetermined threshold value. The method is performed by creating a candidate free image, calculating, for the candidate free image, the probability of there being a target at each pixel, by using Bayes theorem, determining a location of the candidate target K+1 in the image, determining the probability that there is a target at the determined location, by determining the calculated probability of there being a target at the determined location. By performing the above, the most probable locations for targets in the image are located together with the probability that the location holds a true target.
    Type: Application
    Filed: September 21, 2015
    Publication date: September 20, 2018
    Applicant: SAAB AB
    Inventor: Hans HELLSTEN
  • Publication number: 20170299716
    Abstract: A method and system for obtaining SAR images with reduced or eliminated surface clutter to detect subsurface targets, the method comprising the following steps: -selecting a first frequency and an incidence angle for the radar signal such that the ratio of surface backscattering to subsurface target backscattering is significantly larger for vertical polarization than for horizontal -obtaining vertically and horizontally polarized SAR images based on the same SAR path exploiting the selected first frequency and viewing angle -weighting and differencing the vertically and horizontally polarized SAR images so that the surface backscattering completely cancels between the two images and only the combination of the target backscattering components remains.
    Type: Application
    Filed: November 7, 2016
    Publication date: October 19, 2017
    Inventor: Hans Hellsten
  • Patent number: 9618606
    Abstract: An antenna system (100) comprising a single antenna element having first (111) and second (112) antenna ports arranged to pass a respective first and second antenna signal. The first and second antenna signals being derived from a first common antenna signal (J1) and arranged to be essentially equal in envelope. An antenna pattern of the system being arranged to be selectable between a first antenna pattern having a first polarization and a second antenna pattern having a second polarization substantially orthogonal to the first polarization. The first antenna pattern being selected by setting the first and second antenna signal to have the same polarity on first (111) and second (112) antenna ports, the second antenna pattern being selected by setting the first and second antenna signal to have substantially opposite polarities on first (111) and second (112) antenna ports.
    Type: Grant
    Filed: March 12, 2014
    Date of Patent: April 11, 2017
    Assignee: SAAB AB
    Inventor: Hans Hellsten
  • Publication number: 20170016978
    Abstract: An antenna system (100) comprising a single antenna element having first (111) and second (112) antenna ports arranged to pass a respective first and second antenna signal. The first and second antenna signals being derived from a first common antenna signal (J1) and arranged to be essentially equal in envelope. An antenna pattern of the system being arranged to be selectable between a first antenna pattern having a first polarization and a second antenna pattern having a second polarization substantially orthogonal to the first polarization. The first antenna pattern being selected by setting the first and second antenna signal to have the same polarity on first (111) and second (112) antenna ports, the second antenna pattern being selected by setting the first and second antenna signal to have substantially opposite polarities on first (111) and second (112) antenna ports.
    Type: Application
    Filed: March 12, 2014
    Publication date: January 19, 2017
    Inventor: Hans Hellsten
  • Patent number: 9519055
    Abstract: A method and system for obtaining SAR images with reduced or eliminated surface clutter to detect subsurface targets, the method comprising the following steps: —selecting a first frequency and an incidence angle for the radar signal such that the ratio of surface backscattering to subsurface target backscattering is significantly larger for vertical polarization than for horizontal—obtaining vertically and horizontally polarized SAR images based on the same SAR path exploiting the selected first frequency and viewing angle—weighting and differencing the vertically and horizontally polarized SAR images so that the surface backscattering completely cancels between the two images and only the combination of the target backscattering components remains.
    Type: Grant
    Filed: December 17, 2012
    Date of Patent: December 13, 2016
    Assignee: SAAB AB
    Inventor: Hans Hellsten
  • Publication number: 20150331097
    Abstract: A method and system for obtaining SAR images with reduced or eliminated surface clutter to detect subsurface targets, the method comprising the following steps: —selecting a first frequency and an incidence angle for the radar signal such that the ratio of surface backscattering to subsurface target backscattering is significantly larger for vertical polarization than for horizontal —obtaining vertically and horizontally polarized SAR images based on the same SAR path exploiting the selected first frequency and viewing angle —weighting and differencing the vertically and horizontally polarized SAR images so that the surface backscattering completely cancels between the two images and only the combination of the target backscattering components remains.
    Type: Application
    Filed: December 17, 2012
    Publication date: November 19, 2015
    Inventor: Hans Hellsten
  • Patent number: 9071337
    Abstract: A transmitter/receiver arrangement comprises a digital arbitrary waveform generator AWG connected to a transmitter. Said waveform generator is configured to generate an arbitrary waveform within a given bandwidth. Said transmitter/receiver arrangement further comprises an antenna arrangement configured to emit a transmitter signal, and to receive an incident signal, a receiver configured to receive a receiver signal, and an analog isolator connected to said antenna arrangement, said transmitter, and said receiver. Said analog isolator is adapted to route said transmitter signal from said transmitter to said antenna arrangement, and said incident signal from said antenna arrangement to said receiver, and to isolate said transmitter signal from said receiver signal. Said receiver is adapted to cancel any residual transmitter signal in said receiver signal by means of at least one digital model of at least said isolator, said antenna arrangement, and said transmitter.
    Type: Grant
    Filed: February 17, 2010
    Date of Patent: June 30, 2015
    Assignee: SAAB AB
    Inventor: Hans Hellsten
  • Patent number: 8947292
    Abstract: A radar system for a synthetic aperture radar including an arrangement of at least one transmitter, two receivers, two antennas and signal processing means located on a platform. The platform is arranged to move over ground and arranged to transmit a known signal shape and receive signals reflected from the ground. The received signals are used to produce a synthetic aperture radar image of the ground. The synthetic aperture radar image includes a number of resolution cells. The radar system is further arranged to operate in a frequency band with a center frequency and with a wide bandwidth of at least one octave. A first antenna and a second antenna have a length of less than half the wavelength of the center frequency. The radar system is further arranged for: a radar system transfer function to be flat over the frequency band and one-sided beam forming with wideband antenna gain. Also a corresponding method.
    Type: Grant
    Filed: February 6, 2009
    Date of Patent: February 3, 2015
    Assignee: SAAB AB
    Inventors: Lars-Gunnar Andersson, Hans Hellsten
  • Patent number: 8698668
    Abstract: A method for detecting targets including moving and stationary targets with a radar system equipped with Synthetic Aperture Radar (SAR) onboard a SAR platform including navigation equipment for accurate determination of the position of the SAR platform. The SAR platform is transversing a stationary ground region and targets in the ground region, in which the SAR platform obtains radar data utilizing at least one antenna. A SAR processor records the radar data and the position of the antenna or antennas for each transmitted radar pulse. Radar data within synthetic sub-apertures, are successively merged in N iteration steps into SAR images of increasing resolution of the surveyed region and wherein each iteration step includes forming a new SAR image at a new iteration level by a linear combination of neighboring SAR images in the previous iteration step. A radar system and a SAR processor used for calculating the detection and positioning of targets including moving and stationary targets.
    Type: Grant
    Filed: November 11, 2008
    Date of Patent: April 15, 2014
    Assignee: SAAB AB
    Inventor: Hans Hellsten
  • Publication number: 20130201050
    Abstract: A transmitter/receiver arrangement comprises a digital arbitrary waveform generator AWG connected to a transmitter. Said waveform generator is configured to generate an arbitrary waveform within a given bandwidth. Said transmitter/receiver arrangement further comprises an antenna arrangement configured to emit a transmitter signal, and to receive an incident signal, a receiver configured to receive a receiver signal, and an analogue isolator connected to said antenna arrangement, said transmitter, and said receiver. Said analogue isolator is adapted to route said transmitter signal from said transmitter to said antenna arrangement, and said incident signal from said antenna arrangement to said receiver, and to isolate said transmitter signal from said receiver signal. Said receiver is adapted to cancel any residual transmitter signal in said receiver signal by means of at least one digital model of at least said isolator, said antenna arrangement, and said transmitter.
    Type: Application
    Filed: February 17, 2010
    Publication date: August 8, 2013
    Applicant: SAAB AB
    Inventor: Hans Hellsten
  • Publication number: 20120105274
    Abstract: A radar system for a synthetic aperture radar including an arrangement of at least one transmitter, two receivers, two antennas and signal processing means located on a platform. The platform is arranged to move over ground and arranged to transmit a known signal shape and receive signals reflected from the ground. The received signals are used to produce a synthetic aperture radar image of the ground. The synthetic aperture radar image includes a number of resolution cells. The radar system is further arranged to operate in a frequency band with a center frequency and with a wide bandwidth of at least one octave. A first antenna and a second antenna have a length of less than half the wavelength of the center frequency. The radar system is further arranged for: a radar system transfer function to be flat over the frequency band and one-sided beam forming with wideband antenna gain. Also a corresponding method.
    Type: Application
    Filed: February 6, 2009
    Publication date: May 3, 2012
    Applicant: SAAB AB
    Inventors: Lars-Gunnar Andersson, Hans Hellsten
  • Publication number: 20110298654
    Abstract: A method for detecting targets including moving and stationary targets with a radar system equipped with Synthetic Aperture Radar (SAR) onboard a SAR platform including navigation equipment for accurate determination of the position of the SAR platform. The SAR platform is transversing a stationary ground region and targets in the ground region, in which the SAR platform obtains radar data utilizing at least one antenna. A SAR processor records the radar data and the position of the antenna or antennas for each transmitted radar pulse. Radar data within synthetic sub-apertures, are successively merged in N iteration steps into SAR images of increasing resolution of the surveyed region and wherein each iteration step includes forming a new SAR image at a new iteration level by a linear combination of neighboring SAR images in the previous iteration step. A radar system and a SAR processor used for calculating the detection and positioning of targets including moving and stationary targets.
    Type: Application
    Filed: November 11, 2008
    Publication date: December 8, 2011
    Applicant: SAAB AB
    Inventor: Hans Hellsten
  • Patent number: 7932852
    Abstract: A filter scheme for broadcast interference cancellation that is computationally efficient and numerically robust Airborne Low Frequency Synthetic Aperture Radar (SAR) operating in the VHF and UHF bands has been shown. At least interference Doppler filtering or interference cancellation is utilized. The interference cancellation involves prediction of the interference for each particular reception interval of mixed interference and radar ground response. This prediction is then coherently subtracted from the incoming signal.
    Type: Grant
    Filed: May 20, 2009
    Date of Patent: April 26, 2011
    Assignee: Saab AB
    Inventor: Hans Hellsten