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  • 1. Pettersson, Mats
    Detection of Moving Targets in Wideband SAR2004In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 40, no 3, p. 780-796Article in journal (Refereed)
    Abstract [en]

    A likelihood ratio is proposed for moving target detection in a wideband (WB) synthetic aperture radar (SAR) system. WB is defined here as any systems having a large fractional bandwidth, i.e., an ultra wide frequency band combined with a wide antenna beam. The developed method combines time-domain fast backprojection SAR processing methods with moving target detection using space-time processing. The proposed method reduces computational load when sets of relative speeds can be tested using the same clutter-suppressed subaperture beams. The proposed method is tested on narrowband radar data.

  • 2.
    Pettersson, Mats
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Sjögren, Thomas K.
    Vu, Viet T.
    Performance of Moving Target Parameter Estimation Using SAR2015In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 51, no 2, p. 1191-1202Article in journal (Refereed)
    Abstract [en]

    Synthetic aperture radar (SAR) gives not only the opportunity to image targets with high resolution but also to measure their position and velocity. Without acceleration (constant speed), the position and velocity both in range and azimuth can be estimated using a multichannel SAR system. This paper introduces a method to find the lower bound on variance of estimate of position and velocity for targets. The method is based on the assumptions needed for the Cramer-Rao lower bound (CRLB). The method works for both narrowband (NB) and ultrawideband (UWB) SAR systems. For demonstration, a monostatic single-channel UWB SAR system operating at low frequency is used. Thus, only lower bounds for estimate variance of azimuth, range, and relative speed are derived.

  • 3.
    Sjögren, Tomas
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Vu, Viet
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Pettersson, Mats
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Gustavsson, Anders
    Ulander, Lars
    Moving Target Relative Speed Estimation and Refocusing in Synthetic Aperture Radar Images2012In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 48, no 3, p. 2426-2436Article in journal (Refereed)
    Abstract [en]

    In this paper, a method for moving target relative speed estimation and refocusing based on synthetic aperture radar (SAR) images is derived and tested in simulation and on real data with good results. Furthermore, an approach on how to combine the estimation method with the refocusing method is introduced. The estimation is based on a chirp estimator that operates in the SAR image and the refocusing of the moving target is performed locally using subimages. Focusing of the moving target is achieved in the frequency domain by phase compensation, and therefore makes it even possible to handle large range cell migration in the SAR subimages. The proposed approach is tested in a simulation and also on real ultrawideband (UWB) SAR data with very good results. The estimation method works especially well in connection with low frequency (LF) UWB SAR, where the clutter is well focused and the phase of the smeared moving target signal becomes less distorted. The main limitation of the approach is target accelerations where the distortion increases with the integration time.

  • 4.
    Vu, Viet Thuy
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Dämmert, Patrik
    SAAB Surveillance, SWE.
    Hellsten, Hans
    SAAB Surveillance, SWE.
    Two-Dimensional Data Conversion for One-Dimensional Adaptive Noise Canceler in Low Frequency SAR Change Detection2018In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 54, no 5, p. 2611-2618Article in journal (Refereed)
    Abstract [en]

    One-dimensional (1-D) adaptive noise canceler (ANC) has been used for false alarm reduction in low frequency SAR change detection. The paper presents possibilities to process two-dimensional (2-D) data by an 1-D ANC. Beside concatenating the rows of 2-D data in a matrix form to convert it to 1-D data in a vector form, two conversion approaches are considered: concatenating the columns of 2-D data and local concatenation, i.e., the conversion to 1-D is performed locally on each block of the 2-D data. A ground object can occupy more than one row and/or more than one column of 2-D data. In addition, the properties in cross-range and range of an image are not the same. Thus, different conversion approaches may lead to different performance of an 1-D ANC and hence different change detection results. Among the considered approaches, the local concatenating approach is shown to provide slightly better performance in terms of probability of detection and false alarm rate. IEEE

  • 5.
    Vu, Viet Thuy
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Blekinge Institute of Technology, School of Engineering, Department of Signal Processing. Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences. Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    thomas, Sjögren
    Swedish Defence Research Agency, SWE.
    Moving Target Focusing in SAR Image with Known Normalized Relative Speed2017In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 53, no 2, p. 854-861Article in journal (Refereed)
    Abstract [en]

    This paper presents the moving target focusing method, whichallows focusing moving targets in complex synthetic aperture radar(SAR) images without raw data. The method is developed on the rangemigration algorithm, where focusing moving target is an interpolationstep in the wave domain. The simulated results are provided in thepaper to illustrate the proposed method whereas the experimentalresults show its practicality. The method can be flexibly applied fromsmall area to the whole SAR scene.

  • 6.
    Vu, Viet Thuy
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Sjögren, Thomas
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Pettersson, Mats
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Fast Time-Domain Algorithms for UWB Bistatic SAR Processing2013In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 49, no 3, p. 1982-1994Article in journal (Refereed)
    Abstract [en]

    Two fast time-domain algorithms are introduced for ultrawideband-ultrawidebeam (UWB) bistatic synthetic aperture radar (SAR) processing; they are bistatic fast backprojection (BiFBP) and bistatic fast factorized backprojection (BiFFBP). Both algorithms process radar echoes on a subaperture and subimage basis in order to minimize processing time. They are shown to work with any configuration of bistatic SAR. They also own time-domain characteristics, which are essential for UWB radar signal processing. BiFBP and BiFFBP are experimented successfully on the CARABAS-II simulated data.

  • 7.
    Vu, Viet Thuy
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences.
    Sjögren, Thomas
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences.
    Pettersson, Mats
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences.
    On Synthetic Aperture Radar Spatial Azimuth and Range Resolution Equations2012In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 48, no 2, p. 1764-1769Article in journal (Refereed)
    Abstract [en]

    This paper discusses spatial resolutions for narrowband narrowbeam (NB) synthetic aperture radar (SAR) as well as for ultrawideband ultrawidebeam (UWB) SAR. The similarity and difference between the impulse response function in NB SAR imaging (IRF-NSAR) - sinc function - and the impulse response function in UWB SAR imaging (IRF-USAR) is investigated and the result of this investigation shows that in the intensity interval from −6 dB to 0 dB, the behavior of IRF-NSAR and IRF-USAR in azimuth and range are similar. This is the basis for a derivation of new spatial resolution equations for UWB SAR based on −3 dB width or half power beamwidth (HPBW). The investigated result also shows that there exists the so-called HPBW narrowing/broadening factor in an IRF-USAR.

  • 8.
    Vu, Viet Thuy
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Sjögren, Thomas
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Pettersson, Mats
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Phase Error Calculation for Fast Time-Domain Bistatic SAR Algorithms2013In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 49, no 1, p. 631-639Article in journal (Refereed)
    Abstract [en]

    In synthetic aperture radar (SAR) processing, there is a trade-off between accuracy and speed. The approximations in an algorithm help to increase the algorithm’s speed but cause deterministic phase errors which directly affect the SAR image quality. This paper discusses the phase error calculations for bistatic fast backprojection (BiFBP) and bistatic fast factorized backprojection (BiFFBP) which are essential for setting their parameters. The phase error calculation principle for bistatic SAR in comparison to monostatic SAR is presented. This principle is used to derive the maximum phase error equation.

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