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  • 101.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    On Apodization Techniques for Ultra-wideband SAR Imaging2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ultra-wideband (UWB) SAR imaging suffers from a number of inherent problems in which the apodization has not been investigated appropriately. This paper presents a discussion on apodization techniques and possibilities to apply these techniques in UWB SAR imaging.

  • 102.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    On Synthetic Aperture Radar Spatial Azimuth and Range Resolution Equations2012Ingår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 48, nr 2, s. 1764-1769Artikel i tidskrift (Refereegranskat)
    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.

  • 103.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Phase Error Calculation for Fast Time-Domain Bistatic SAR Algorithms2013Ingår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 49, nr 1, s. 631-639Artikel i tidskrift (Refereegranskat)
    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.

  • 104.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    SAR Imaging in Ground Plane Using Fast Backprojection for Mono- and Bistatic Cases2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper discusses the possibilities to reconstruct an illuminated Synthetic Aperture Radar (SAR) scene in a ground plane instead of a slant-range plane using Fast Backprojection (FBP) algorithm. Hence, two methods to reconstruct a SAR scene in a ground plane are introduced in this paper. The methods are then considered to be extended for bistatic cases where the formation of a SAR scene in a ground plane is highly recommended. The proposals are examined with simulated SAR data and the simulation results indicate that rebuilding a SAR scene in a ground plane using FBP is possible.

  • 105. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Space time adaptive processing for moving target detection and imaging in bistatic SAR2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    A combination of space time adaptive processing (STAP) and bistatic SAR seems to bring a promising technique of moving target detection and imaging. Moving target detection based on STAP is the most advanced and reliable detection method and mainly used in multichannel monostatic SAR whereas bistatic SAR has shown unique advantages such as the flexibility in design and the ability to observe a target with different angles. The paper investigates the possibility to employ STAP for detection and imaging of moving targets in bistatic SAR.

  • 106. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Ultrawideband Chirp Scaling Algorithm2010Ingår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 7, nr 2, s. 281-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new version of chirp scaling (CS), the so-called ultrawideband (UWB) CS (UCS), is proposed in this letter. UCS aims at UWB synthetic aperture radar (SAR) systems utilizing large fractional bandwidth and wide antenna beamwidth associated with a wide integration angle. Furthermore, it is also valid for SAR systems with special characteristics such as ground moving target indication SAR systems with a very high pulse repetition frequency.

  • 107.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Dahl, Mattias
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Measurement of traffic flows with SAR: Field test on the swedish road network2017Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS), Institute of Electrical and Electronics Engineers Inc. , 2017, s. 3321-3324Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper reports the measurement campaign Blekingetraffic that was performed by Blekinge Institute of Technology with collaboration with the partners. The measurements are part of a case study to evaluate the feasibility of spaceborne SAR for measuring traffic flow change before and after toll charge introduced in Sweden. The radar measurements were conducted around Pukavik, western of Karlshamn, Sweden in the end of 2015 and in the beginning of 2016. In this paper, the results of one of the controlled measurements performed in the first week of February 2016 is presented. In the ground scene, some trucks tracked with GPS were deployed in European route E22 and local roads. The trucks have either cabinets or food tankers resulting in different radar cross sections. The data acquisition is with TanDEM-X using two satellites giving up to 6 data channels. Since the measurements were performed at 5:00 pm there were unknown traffic i.e. trucks and cars that were not controlled. Therefore, the traffic on the roads was recorded by cameras next to the road and on a drone. The initial analysis of the measured data shows the possibilities to apply available processing techniques such as ground moving target indication and change detection to obtain the knowledge of traffic flow change. © 2017 IEEE.

  • 108. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Gustavsson, Anders
    Definition on SAR image quality measurements for UWB SAR2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Analyses in this study show that measurements under currently used definitions on SAR image quality measurement may be unsuitable for UWB SAR. The main objective of this paper is therefore to propose a definition based on the shape of a single point target in a SAR image which is more suitable for UWB SAR. We use both real and simulated data based on the airborne UWB low frequency SAR CARABAS-II in experiments. The time-domain algorithm Global Backprojection (GBP) is selected for the image formation in this study.

  • 109. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Gustavsson, Anders
    Ulander, Lars
    Detection of Moving Targets by Focusing in UWB SAR—Theory and Experimental Results2010Ingår i: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 48, nr 10, s. 3799-3815Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Moving-target detection in ultrawideband (UWB) synthetic aperture radar (SAR) is associated with long integration time and must accommodate azimuth focusing for reliable detection. This paper presents the theory on detection of moving targets by focusing and experimental results on single-channel SAR data aimed at evaluating the detection performance. The results with respect to both simulated and real data show that the ability to detect moving targets increases significantly when applying the proposed detection technique. The improvement in signal-to-clutter noise ratio, which is a basic requisite for evaluating the performance, reaches approximately 20 dB, using only single-channel SAR data. This gain will be preserved for the case of multichannel SAR data. The reference system for this study is the airborne UWB low-frequency SAR Coherent All RAdio BAnd Sensing II.

  • 110. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Hellsten, Hans
    An Impulse Response Function for Evaluation of UWB SAR Imaging2010Ingår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 58, nr 7, s. 3927-3932Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on analysis of a point target imaged by different synthetic aperture radar (SAR) systems, the commonly used impulse response function in SAR Imaging (IRF-SAR)—a two-dimensional (2-D) sinc function—is shown to be inappropriate for ultrawideband-ultrawidebeam (UWB) SAR systems utilizing a large fractional signal bandwidth and a wide antenna beamwidth. As a consequence, the applications of the 2-D sinc function such as image quality measurements and spatial resolution estimations are limited to narrowband-narrowbeam (NB) SAR systems exploiting a small fractional signal bandwidth and a narrow antenna beamwidth. In this paper, a more general IRF-SAR, which aims at UWB SAR systems, is derived with an assumption of flat two-dimensional (2-D) Fourier transform (FT) of a SAR image and called IRF-USAR. However, the derived IRF-USAR is also valid for NB SAR systems.

  • 111. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Håkansson, Lars
    An Approach to Suppress RFI in Ultrawideband Low Frequency SAR2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper proposes an approach for the Radio Frequency Interference (RFI) suppression in ultrawideband (UWB) low frequency Synthetic Aperture Radar (SAR). The basis of the approach is an Adaptive Line Enhancer (ALE) controlled by the Normalized Least Mean Square (NLMS) algorithm. The proposal is tested successfully on the simulated CARABAS-II data.

  • 112. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Håkansson, Lars
    Gustavsson, Anders
    Ulander, Lars
    RFI Suppression in Ultrawideband SAR Using an Adaptive Line Enhancer2010Ingår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 7, nr 4, s. 694-698Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, we propose an approach to suppress radio-frequency interference (RFI) in ultrawideband (UWB) low-frequency synthetic aperture radar (SAR). According to the proposal, RFI is suppressed by using an adaptive line enhancer controlled by the normalized least mean square algorithm. The approach is tested successfully on real UWB low-frequency SAR data. In order to keep the computational burden down, possible ways to integrate the RFI suppression approach into SAR imaging algorithms are also suggested.

  • 113. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Marques, Paulo
    Application of Moving Target Detection by Focusing Technique in Civil Traffic Monitoring2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an application of the detection of moving target by focusing technique (DMTF) in civil traffic monitoring. With an assumption of known moving directions of vehicles, DMTF allows first detecting these vehicles, then estimating their speed and finally imaging the vehicles of interest. With DMTF, the civil traffic monitoring requires only a singlechannel airborne SAR system.

  • 114.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Minardi, Michael
    The Availability ff Fast Time-Domain Algorithms for Circular Sar Data Processing2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper shows an investigation of the availability of the fast time-domain algorithms to process data collected by synthetic aperture radar systems with circular apertures (CSAR). In the investigation, the reconstruction of CSAR images from data is suggested to be in a ground plane instead of a slant-range plane. The Fast Backprojection (FBP) algorithms are considered to examine the availability of time-domain algorithms for CSAR data processing. However, the availability is also applied to the Fast Factorized Backprojection (FFBP) algorithms. The simulated CSAR data with respect to the CARABAS-II parameters is used.

  • 115. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Zepernick, Hans-Jürgen
    Gustavsson, Anders
    Experimental Results on Moving Targets Focusing in UWB Low Frequency SAR2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main objective of this paper is to present and evaluate a method to detect moving targets in Ultra Wideband (UWB) low frequency Synthetic Aperture Radar (SAR). Moving target detection at low radar frequencies is associated with long integration time and has to handle azimuth focusing for reliable detection. The examined method tests different hypotheses on relative speeds in the area of interest. The optimum step size between the hypotheses is found from a point target approximation. Experimental results show that the ability to detect moving targets increases significantly. In this study, the improvement of the Signal-to-Clutter Noise Ratio (SCNR) is up to approximately 20dB using a single antenna. The focusing method allows initial estimates in speed of moving targets. The SAR data, which is used in our experiments, was collected by the airborne UWB low frequency CARABAS-II system.

  • 116.
    Zepernick, Hans-Jürgen
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Quality of Experience Based Cross-Layer Design of Mobile Video Systems2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper introduces and discusses quality of experience based cross-layer design of mobile video systems as a means of providing technologies for jointly analyzing, adopting, and optimizing system quality. The many benefits of our novel approaches over traditional concepts will range from efficient video processing techniques over advanced real-time scheduling algorithms, to networking and service level management techniques. This will lead to better service quality and resource utilization in mobile video systems.

  • 117. Zetterberg, Viktoria
    et al.
    Pettersson, Mats
    Claesson, Ingvar
    Acoustic passive 3D imaging method for scattered array2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    An acoustic passive positioning/image method using widely distributed sensors in a network is shown. Previous studies have shown that, despite decreased coherence (due to the larger sensor separation) between sensor signals, a scattered array can give a better positioning capabillity. The positioning method divides the water into volumes and uses a weighting of each sensor pair’s correlation (Generalized Cross Correlation) result to test each volume individually. Various aspects can govern the weight assigned to a sensor pair and we have in this paper used distance from sensor to target. By projecting the correlation results over the map an intersection point is found. By looking at different depths the intersection point is found at the layer where the sound source is located. 3D positioning though requires an end fire sensor pair close to the sound source. The more pairs of that kind, the better the position in 3D will be. The developed method is tested on both simulations and real measurement data from a measurement campaign along the Swedish coastline. In order to image moving targets by scattered sensors it is also important to Doppler compensate.

  • 118. Zetterberg, Viktoria
    et al.
    Pettersson, Mats
    Claesson, Ingvar
    Comparison between whitened generalized cross correlation and adaptive filter for time delay estimation with scattered arrays for passive positioning of moving targets in Baltic Sea shallow waters2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Results from an acoustic measurement campaign in shallow waters (at 22 meters depth) are given. Eight hydrophones, placed at the seabed, were used simultaneously to investigate how different distances between hydrophones affect the Time Delay Estimation (TDE). In order to position targets two TDE methods were applied. The used methods were the Generalized Cross Correlation (GCC) function weighted by the Phase Transform (PHAT) and an adaptive Normalized Least Mean Square (NLMS) filter estimating the TDE between pairs of sensors. The two methods gave approximately the same result, except for the largest baseline where the GCC PHAT performed better. In the study we found that increasing separation distance decrease the bandwidth of coherence between the signals, however the study also indicated that scattered arrays with large baselines has better positioning capability than those with small baselines.

  • 119. Zetterberg, Viktoria
    et al.
    Pettersson, Mats
    Tegberg, Lars
    Claesson, Ingvar
    Passive scattered array positioning method for underwater acoustic source2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper considers large scattered arrays for 3D underwater acoustic positioning and imaging, where the hydrophone sensors, in the array, form a network over the total area of interest. A method where the Generalized Cross Correlation (GCC) function is projected over the volume is being used, and 3D images are formed. In this paper we determine the discretization of these images so they fulfill the Nyqvist criteria. In order to detect and position targets by scattered sensors it is important to Doppler compensate and weight the different sensor pair results. In this paper we divide the water into volumes where Doppler compensation and pair weights are implemented for each volume individually. Various aspects can govern the weights assigned to a sensor pair and in this paper we have used opening angle between sensor pair and target. The baseline of the sensor pairs varies from 17 – 181 meters, therefore different frequency bandwidths for each sensor pair is used. The developed method is tested on both simulations and real measurement for a surface target.

123 101 - 119 av 119
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Permanent länk
Referera
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  • apa
  • ieee
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  • vancouver
  • Annat format
Fler format
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  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
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Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf