The Experts below are selected from a list of 5619 Experts worldwide ranked by ideXlab platform
Lawrence Carin - One of the best experts on this subject based on the ideXlab platform.
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optimal time domain detection of a deterministic Target Buried under a randomly rough interface
IEEE Transactions on Antennas and Propagation, 2001Co-Authors: Traian Dogaru, Leslie M Collins, Lawrence CarinAbstract:We consider pulsed plane-wave scattering from Targets Buried under a rough air-ground interface. The properties of the interface are parametrized as a random process with known statistics, and therefore the fields scattered from a particular surface constitute one realization of an ensemble, characterized by corresponding statistics. Moreover, since the fields incident upon a Buried Target must first penetrate the rough interface, they and the subsequent scattered fields are random processes as well. Based on this understanding, an optimal detector is formulated, accounting for the clutter and Target-signature statistics (the former due to scattering at the rough surface, and the latter due to transmission); the statistics of these two processes are in general different. The detector performance is compared to that of a matched filter, which assumes the Target signature is known exactly (i.e., nonrandom). The results presented here, as a function of angle and polarization, demonstrate that there is often a significant gain in detector performance if the Target signature is properly treated as a random process.
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Ultra-wideband, short-pulse ground-penetrating radar: simulation and measurement
IEEE Transactions on Geoscience and Remote Sensing, 1997Co-Authors: Stanislav Vitebskiy, Lawrence Carin, Marc A. ResslerAbstract:Ultra-wideband (UWB), short-pulse (SP) radar is investigated theoretically and experimentally for the detection and identification of Targets Buried in and placed atop soil. The calculations are performed using a rigorous, three-dimensional (3D) method of moments algorithm for perfectly conducting bodies of revolution. Particular Targets investigated theoretically include anti-personnel mines, anti-tank mines, and a 55-gallon drum, for which the authors model the time-domain scattered fields and the Buried-Target late-time resonant frequencies. With regard to the latter, the computed resonant frequencies are utilized to assess the feasibility of resonance-based Buried-Target identification for this class of Targets. The measurements are performed using a novel UWB, SP synthetic aperture radar (SAR) implemented on a mobile boom. Experimental and theoretical results are compared.
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resonances of perfectly conducting wires and bodies of revolution Buried in a lossy dispersive half space
IEEE Transactions on Antennas and Propagation, 1996Co-Authors: Stanislav Vitebskiy, Lawrence CarinAbstract:The method of moments (MoM) is utilized to compute the complex resonant frequencies and modal currents of perfectly conducting wires and bodies of revolution Buried in a lossy dispersive half space. To make such an analysis tractable computationally, the half-space Green's function is computed via the method of complex images, with appropriate modifications made to account for the complex frequencies characteristic of resonant modes. Results are presented for wires and bodies of revolution Buried in lossy soil using frequency-dependent measured parameters for the complex permittivity, and we demonstrate that the resonant frequencies generally vary with Target depth. In addition to presenting results, relevant issues are addressed concerning the numerical computation of Buried-Target resonant frequencies.
Traian Dogaru - One of the best experts on this subject based on the ideXlab platform.
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investigation of airborne synthetic aperture radar parameters for Buried Target detection
Radar Sensor Technology XXIII, 2019Co-Authors: Colin D Kelly, Brian R Phelan, Traian Dogaru, Kelly D Sherbondy, Ram M NarayananAbstract:Explosive hazards pose a threat to both civilians and warfighters in areas of current and past conflict. The U.S. Army Combat Capabilities Development Command (CCDC) has been exploring the use of an unmanned aerial vehicle (UAV)-mounted ultra-wideband (UWB) radar to image and detect obscured explosive hazards. In a stripmap modality, a synthetic aperture radar system travels in a straight line and takes measurements perpendicular to the platform’s direction of travel. The large angular diversity provided by the platform motion yields a fine cross-range resolution of the imaged scene. This problem space is being simulated in MATLAB to determine the feasibility of Buried Target detection and to identify the optimal parameters of operation on a UAV. Parameters such as platform height, incident angle, and bandwidth are investigated. It is shown that performance at different platform heights is determined by the dependence of the signal-to-noise ratio (SNR) on elevation. Furthermore, a minimum platform height is required to meet the minimum requirements of the time-bandwidth product for pulsed waveforms. An optimal transmit angle can be found by maximizing the Target-to-clutter ratio (TCR). The Target radar cross section (RCS) is taken from finite-difference time-domain (FDTD) models of Targets of interest, and the clutter is simulated using the small perturbation method (SPM) for distributed clutter. Finally, the required resolution and bandwidth of the system are presented.
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Imaging of Buried Targets using UAV-based, ground penetrating, synthetic aperture radar
Radar Sensor Technology XXIII, 2019Co-Authors: Traian Dogaru, Brian R Phelan, Dahan LiaoAbstract:This paper investigates the possible configurations of a ground penetrating radar (GPR) system installed on a small UAV platform and used for Buried Target imaging. After discussing the advantages of this type of platform as compared to existing designs, we proceed to analyzing the imaging performance of the proposed system. This is done first by simulating the point spread function of the system, then by using realistic radar models involving a Buried antitank landmine. The study has the following objectives: finding the best sensing geometry for this type of Targets; optimizing the frequency band, polarization, and synthetic aperture length, position and sampling rate for best imaging performance; and developing SAR image formation algorithms for this GPR system. Both 2-D and 3-D GPR imaging systems are considered in this work, emphasizing the advantages of certain sensing modalities over the others. Image attributes such as resolution, grating lobes, signal strength, ground bounce separation and surface clutter sensitivity are used in the performance comparison.
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performance of free space tomographic imaging approximation for shallow Buried Target detection
IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing, 2017Co-Authors: Davide Comite, Fauzia Ahmad, Traian DogaruAbstract:Forward-looking ground penetrating radar (FL-GPR) is an emerging modality that permits standoff sensing of Targets Buried at shallow depths in the ground. Most FL-GPR imagery is obtained using free-space approximation, neglecting the presence of the air-to-ground interface and assuming the propagation as occurring in a homogeneous dielectric medium. In this paper, we compare the performance of the approximate free-space tomographic imaging with that of a tomographic algorithm which accounts for the presence of the actual halfspace geometry. The half-space approach implements the spectral representation of the dyadic Green's function. Using numerical electromagnetic FL-GPR data, we investigate the impact of the free-space approximation on the image quality as well on the image-domain statistics of the Targets and rough surface clutter.
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Buried Target radar imaging with an ultra wideband vehicle mounted antenna array
Proceedings of SPIE, 2013Co-Authors: Kenneth I Ranney, Dahan Liao, Traian Dogaru, Chi Tran, Lam H NguyenAbstract:The problem of detecting Buried objects has engaged radar system developers for quite some time. Many systems—both experimental and commercial—have been developed, including vehicle-mounted systems that look beneath road surfaces. Most of these downward-looking systems exploit multiple transmit and receive channels to enhance resolution in the final radar imagery used for Target detection. In such a system, the configuration and operation of the various transmit and receive elements play a critical role in the quality of the output imagery. In what follows, we leverage high-fidelity electromagnetic model data to examine a multistatic downward-looking radar system. We evaluate the signatures produced by various Targets of interest and describe, both qualitatively and quantitatively, the variations in Target signatures produced by different system configurations. Finally, we analyze the underlying physics of the problem to explain certain characteristics in the observed Target signatures.
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optimal time domain detection of a deterministic Target Buried under a randomly rough interface
IEEE Transactions on Antennas and Propagation, 2001Co-Authors: Traian Dogaru, Leslie M Collins, Lawrence CarinAbstract:We consider pulsed plane-wave scattering from Targets Buried under a rough air-ground interface. The properties of the interface are parametrized as a random process with known statistics, and therefore the fields scattered from a particular surface constitute one realization of an ensemble, characterized by corresponding statistics. Moreover, since the fields incident upon a Buried Target must first penetrate the rough interface, they and the subsequent scattered fields are random processes as well. Based on this understanding, an optimal detector is formulated, accounting for the clutter and Target-signature statistics (the former due to scattering at the rough surface, and the latter due to transmission); the statistics of these two processes are in general different. The detector performance is compared to that of a matched filter, which assumes the Target signature is known exactly (i.e., nonrandom). The results presented here, as a function of angle and polarization, demonstrate that there is often a significant gain in detector performance if the Target signature is properly treated as a random process.
Stanislav Vitebskiy - One of the best experts on this subject based on the ideXlab platform.
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Ultra-wideband, short-pulse ground-penetrating radar: simulation and measurement
IEEE Transactions on Geoscience and Remote Sensing, 1997Co-Authors: Stanislav Vitebskiy, Lawrence Carin, Marc A. ResslerAbstract:Ultra-wideband (UWB), short-pulse (SP) radar is investigated theoretically and experimentally for the detection and identification of Targets Buried in and placed atop soil. The calculations are performed using a rigorous, three-dimensional (3D) method of moments algorithm for perfectly conducting bodies of revolution. Particular Targets investigated theoretically include anti-personnel mines, anti-tank mines, and a 55-gallon drum, for which the authors model the time-domain scattered fields and the Buried-Target late-time resonant frequencies. With regard to the latter, the computed resonant frequencies are utilized to assess the feasibility of resonance-based Buried-Target identification for this class of Targets. The measurements are performed using a novel UWB, SP synthetic aperture radar (SAR) implemented on a mobile boom. Experimental and theoretical results are compared.
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resonances of perfectly conducting wires and bodies of revolution Buried in a lossy dispersive half space
IEEE Transactions on Antennas and Propagation, 1996Co-Authors: Stanislav Vitebskiy, Lawrence CarinAbstract:The method of moments (MoM) is utilized to compute the complex resonant frequencies and modal currents of perfectly conducting wires and bodies of revolution Buried in a lossy dispersive half space. To make such an analysis tractable computationally, the half-space Green's function is computed via the method of complex images, with appropriate modifications made to account for the complex frequencies characteristic of resonant modes. Results are presented for wires and bodies of revolution Buried in lossy soil using frequency-dependent measured parameters for the complex permittivity, and we demonstrate that the resonant frequencies generally vary with Target depth. In addition to presenting results, relevant issues are addressed concerning the numerical computation of Buried-Target resonant frequencies.
Keith Morrison - One of the best experts on this subject based on the ideXlab platform.
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verification of the virtual bandwidth sar scheme for centimetric resolution subsurface imaging from space
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: Alexander Edwardssmith, Keith Morrison, Simon Zwieback, Irena HajnsekAbstract:This paper presents the first experimental demonstration of the virtual bandwidth synthetic aperture radar (VB-SAR) imaging scheme. VB-SAR is a newly developed subsurface imaging technique which, in stark contrast to traditional close proximity ground penetrating radar schemes, promises imaging from remote standoff platforms such as aircraft and satellites. It specifically exploits the differential interferometric SAR (DInSAR) phase history of a radar wave within a drying soil volume to generate high-resolution vertical maps of the scattering through the soil volume. For this study, a stack of C-band vertically polarized DInSAR images of a sandy soil containing a Buried Target was collected in the laboratory while the soil moisture was varied—first during controlled water addition, and then during subsequent drying. The wetting image set established the moisture-phase relationship for the soil, which was then applied to the drying DInSAR image set using the VB-SAR scheme. This allowed retrieval of high-resolution VB-SAR imagery with a vertical discrimination of 0.04 m from a stack of 1-m vertical resolution DInSAR images. This paper unequivocally shows that the basic principles of the VB-SAR technique are valid and opens the door to further investigation of this promising technique.
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Using DInSAR to Separate Surface and Subsurface Features
IEEE Transactions on Geoscience and Remote Sensing, 2013Co-Authors: Keith Morrison, J.c. Bennett, Matt NolanAbstract:We report on an investigation into the use of differential interferometric synthetic aperture radar (SAR) (DInSAR) for the discrimination between surface and subsurface features in a soil, undertaken at the Ground-Based SAR Microwave Measurement Facility. A temporal sequence of C-band VV SAR images of a drying soil containing a Buried Target was collected. While the phase record of the signal identified with the soil return showed almost no variation, in stark contrast, the phase from the Buried Target showed a strongly linear change with time. A model is presented, which describes the observed phase changes in terms of retardation of the signal by the soil dielectric properties, which are dependent upon the moisture content. The model confirms a strongly linear relationship between phase and volumetric soil moisture. The linearity promises to greatly simplify any exploitation scheme, and such a DInSAR scheme would be applicable at large standoff distances from airborne and spaceborne platforms, in contrast to current subsurface techniques which rely on close-in measurement to spatially isolate returns vertically in backscatter.
Irena Hajnsek - One of the best experts on this subject based on the ideXlab platform.
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verification of the virtual bandwidth sar scheme for centimetric resolution subsurface imaging from space
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: Alexander Edwardssmith, Keith Morrison, Simon Zwieback, Irena HajnsekAbstract:This paper presents the first experimental demonstration of the virtual bandwidth synthetic aperture radar (VB-SAR) imaging scheme. VB-SAR is a newly developed subsurface imaging technique which, in stark contrast to traditional close proximity ground penetrating radar schemes, promises imaging from remote standoff platforms such as aircraft and satellites. It specifically exploits the differential interferometric SAR (DInSAR) phase history of a radar wave within a drying soil volume to generate high-resolution vertical maps of the scattering through the soil volume. For this study, a stack of C-band vertically polarized DInSAR images of a sandy soil containing a Buried Target was collected in the laboratory while the soil moisture was varied—first during controlled water addition, and then during subsequent drying. The wetting image set established the moisture-phase relationship for the soil, which was then applied to the drying DInSAR image set using the VB-SAR scheme. This allowed retrieval of high-resolution VB-SAR imagery with a vertical discrimination of 0.04 m from a stack of 1-m vertical resolution DInSAR images. This paper unequivocally shows that the basic principles of the VB-SAR technique are valid and opens the door to further investigation of this promising technique.
