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  • Artikel  (1.467)
  • 2015-2019  (1.467)
  • Geologie und Paläontologie  (1.467)
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  • Artikel  (1.467)
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  • 11
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    Human Target Localization Algorithm Using Energy Operator and Doppler Processing (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: In this letter, a localization algorithm, which combines energy operator with Doppler processing, is proposed for Doppler radar human sensing applications. For this algorithm, the energy operator is first used to extract the target components of interest from radar echoes and estimate their instantaneous frequencies (IFs). Then, on the basis of the IF estimation result, Doppler processing is applied to synthesize the target movement trajectories. Compared with the traditional localization methods, the proposed algorithm can more precisely estimate the target movement trajectory. Besides, it can further avoid the frequency ambiguity issue, and thus can be very promising for multitarget sensing applications. Experimental results are shown to demonstrate the performance of the proposed algorithm.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 12
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    Knowledge-Aided Covariance Matrix Estimation via Kronecker Product Expansions for Airborne STAP (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: This letter proposes a new approach for knowledge-aided estimation of structured clutter covariance matrices (CCMs) in airborne radar systems with limited training data. First, we model the CCM in space–time adaptive processing (STAP) as a sum of low-rank Kronecker products. We then apply a permutation operation to convert the Kronecker factors into linear structures and propose a novel CCM estimation method under the maximum-likelihood framework. Employing a proximal gradient algorithm, the proposed method simultaneously exploits the knowledge about the clutter and the Kronecker structure of the CCM. We finally evaluate the performance of the proposed method using real data from airborne STAP.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 13
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    Brewster Angle Damping Observed in the TerraSAR-X Synthetic Aperture Radar Images of Man-Made Targets (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: This letter shows the phenomena of Brewster angle damping and its implication observed in the synthetic aperture radar (SAR) images of concrete constructions, such as a bridge and seawalls over the sea. The Fresnel reflection coefficient of concrete material is close to zero at the Brewster angle for X-band V-polarization microwave. The TerraSAR-X images of Tokyo Bay, Japan, at small incidence angles (20.1°–21.4°) showed strong double-bounce reflection between the sea surface and coastal structure with HH-polarization, whereas very little radar backscatter was observed with VV-polarization. The same little radar backscatter was seen in the images of concrete walls on ground and swamp areas covered with reeds. This effect is illustrated with HH/VV intensity and phase difference images, and ground survey data; its implication is also suggested for a better understanding of polarimetric SAR images.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 14
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    Quantitative Stability Analysis of Ground Penetrating Radar Systems (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: The hardware instability of a ground penetrating radar (GPR) system has a severe impact on the quantitative analysis of GPR data, which is aimed for material characterization and subsurface monitoring. In this letter, an instability index is proposed to quantify the stability performance of a GPR system and the influences of the GPR system type, warm-up time, environmental noise, and the antenna vibration on it are evaluated through a series of laboratory experiments on a sandbox model. It is found that the GPR signal recorded by a stepped-frequency GPR system based on a vector network analyzer is much more stable than that by a commercial impulse GPR system at a cost of more sweep time. A warm-up time of several minutes is enough for an impulse GPR system. Environmental noise has a negligible influence on the stability performance of a GPR system. Mechanical vibrations of GPR antennas have a severe impact on the stability performance of the GPR system, and the instability index and timing jitter can be increased by more than one order of magnitude in a vibrating condition over those in a static condition. The instability index of the direct signal has a negligible difference with that of the reflection signal from a metal plate; thus, a simple measurement of direct signal on the ground surface is suggested for the evaluation of the instability of a GPR system in field in the future.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 15
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    An Image Transform Based on Temporal Decomposition (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: Today, very dense synthetic aperture radar (SAR) time series are available through the framework of the European Copernicus Programme. These time series require innovative processing and preprocessing approaches including novel speckle suppression algorithms. Here we propose an image transform for hypertemporal SAR image time stacks. This proposed image transform relies on the temporal patterns only, and therefore fully preserves the spatial resolution. Specifically, we explore the potential of empirical mode decomposition (EMD), a data-driven approach to decompose the temporal signal into components of different frequencies. Based on the assumption that the high-frequency components are corresponding to speckle, these effects can be isolated and removed. We assessed the speckle filtering performance of the transform using hypertemporal Sentinel-1 data acquired over central Germany comprising 53 scenes. We investigated speckle suppression, ratio images, and edge preservation. For the latter, a novel approach was developed. Our findings suggest that EMD features speckle suppression capabilities similar to that of the Quegan filter while preserving the original image resolution.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 16
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    Tensorization of Multifrequency PolSAR Data for Classification Using an Autoencoder Network (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: A novel tensorization framework is proposed, which utilizes the Kronecker product to combine multifrequency polarimetric synthetic aperture radar data in conjunction with an artificial neural network (ANN) for classification. The ANN comprises of two stages, where an unsupervised stochastic sampling autoencoder learns an efficient representation and a supervised feed forward network performs classification. The proposed framework is demonstrated using multifrequency (C-, L-, and P-bands) data sets collected by the AIRSAR system. The classification performance of single tensor product of dual- and triple-band combinations is evaluated. It is observed that the classification accuracy of the tensor products outperforms single, as well as, the simple augmentation of the frequency bands.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 17
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    Adaptive Probability Thresholding in Automated Ice and Open Water Detection From RADARSAT-2 Images (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: In this letter, we introduce adaptive probability thresholding in addition to our previously developed technique for automated detection of ice and open water from RADARSAT-2 ScanSAR dual-polarization HH–HV images. Situations where the probability threshold needs to be modified were identified based on the analysis of misclassified ice and water samples when the static probability threshold of 0.95 is applied. We found that with the use of the proposed approach, the fraction of misclassified ice samples decreased from 0.98% to 0.24% and the fraction of misclassified water samples decreased from 0.35% to 0.09% in the most clean verification scenario against Canadian Ice Service Image Analysis pure ice and water data, while the fraction of correctly classified ice and water samples did not decrease appreciably, from 72.2% to 65.4%. The developed approach will be implemented as a part of the data assimilation component of the operational Environment and Climate Change Canada Regional Ice-Ocean Prediction System.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 18
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    SAR Focus Theory of Complicated Range Migration Signatures Due to Moving Targets (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: Recent studies have revealed that the residual range migration effects of synthetic aperture radar (SAR) imagery smears induced by moving targets can exhibit complicated shapes that are not limited to that of parabolas. This letter demonstrates that automatic focusing methods can remove such range migration effects by estimating and compensating for phase errors directly in the radar video phase history domain. This approach is validated using measured Ku-band SAR clutter data containing buildings and foliage.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 19
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    Focus High-Resolution Highly Squint SAR Data Using Azimuth-Variant Residual RCMC and Extended Nonlinear Chirp Scaling Based on a New Circle Model (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: The combination of linear range walk correction and keystone transform is a good choice to focus high-resolution highly squint synthetic aperture radar (SAR) data because it is an effective way to remove linear range cell migration (RCM) completely and mitigate range–azimuth coupling. However, the results of this kind of imaging algorithm produce 2-D-variant residual RCM and variant-dependence Doppler phases. To obtain high-quality SAR image, an improved imaging algorithm using an azimuth-variant residual RCM correction (RCMC) and an extended nonlinear chirp scaling (ENLCS) is proposed in this letter. A new circle model is constructed to analyze the azimuth-variant properties of the residual high-order RCM and the Doppler phases. Based on this circle model, an azimuth-variant residual RCMC is implemented by multiplying a fourth-order phase function, and an improved ENLCS is derived to accomplish the azimuth equalization for azimuth compression. Simulation results validate the excellent performance of the proposed algorithm.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 20
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    Target Detection by Exploiting Superpixel-Level Statistical Dissimilarity for SAR Imagery (2018)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publikationsdatum: 2018-03-28
    Beschreibung: In this letter, we propose a superpixel-level target detection approach for synthetic aperture radar (SAR) images. With superpixel segmentation, SAR image is divided into meaningful patches and more statistical information can be provided in superpixels compared with single pixels. The statistical difference between target and clutter superpixels can be measured with the intensity distributions of pixels in them. With the assumption of SAR data obeying Gamma distribution, the superpixel dissimilarity is defined. With this basis, the global and local contrast can be obtained and integrated to enhance target and suppress clutter simultaneously. Thus, better target detection performance can be achieved. Different from traditional target detection schemes based on backscattering difference between target and clutter pixels, the proposed method relies on the statistical difference of superpixels. The effectiveness of the proposed method can be demonstrated with experimental results on real SAR images.
    Print ISSN: 1545-598X
    Digitale ISSN: 1558-0571
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie , Geologie und Paläontologie
    Publiziert von Institute of Electrical and Electronics Engineers (IEEE)
    Standort Signatur Einschränkungen Verfügbarkeit
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