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Reference BookDOI

Through-the-Wall Radar Imaging

01 Jan 2011-
TL;DR: In this article, through-the-wall radar images are used to detect and detect targets behind walls. But the authors focus on the detection of targets behind the walls and do not consider the detection and identification of targets in front of the walls.
Abstract: Wall Attenuation and Dispersion, A. Hussein Muqaibel, M.A. Alsunaidi, Nuruddeen M. Iya, and A. Safaai-Jazi Antenna Elements, Arrays, and Systems for Through-the-Wall Radar Imaging, A. Hoorfar and A. Fathy Beamforming for Through-the-Wall Radar Imaging, G. Alli and D. DiFilippo Image and Localization of Behind-the-Wall Targets Using Collocated and Distributed Apertures, Y.D. Zhang and A. Hunt Conventional and Emerging Waveforms for Detection and Imaging of Targets behind Walls, F. Ahmad and R.M. Narayanan Inverse Scattering Approaches in Through-the-Wall Imaging, K. Sarabandi, M. Thiel, M. Dehmollaian, R. Solimene, and F. Soldovieri Through-the-Wall Microwave Building Tomography, P.B. Weichman, E.M. Lavely, E.H. Hill III, and P. Zemany Analytical Ray Methods for Through-the-Wall Radar Imaging, R.J. Burkholder, R.J. Marhefka, and J.L. Volakis Synthetic Aperture Radar Techniques for Through-the-Wall Imaging, T. Dogaru and C. Le Impulse SAR and Its Application for Through-the-Wall Detection and Identification of People and Weapons, J.Z. Tatoian Through-the-Wall SAR for Characterization of Building Interior Structure Using Attributed Scattering Center Features, E. Ertin and R.L. Moses Detection Approaches in Through-the-Wall Radar Imaging, C. Debes and A.M. Zoubir Detection of Concealed Targets in Through-the-Wall Imaging, L. Crocco Fast Acquisition and Compressive Sensing Techniques for Through-the-Wall Radar Imaging, M. Amin, Y-S. Yoon, and S. Kassam Radar Micro-Doppler Signatures for Characterization of Human Motion, V.C. Chen, G.E. Smith, K. Woodbridge, and C.J. Baker Index
Citations
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Journal ArticleDOI
TL;DR: The results presented show the first through-the-wall (TTW) detections of moving personnel using passive WiFi radar, and it is shown that a new interference suppression technique based on the CLEAN algorithm can improve the SIR by approximately 19 dB.
Abstract: In this paper, we investigate the feasibility of uncooperatively and covertly detecting people moving behind walls using passive bistatic WiFi radar at standoff distances. A series of experiments was conducted which involved personnel targets moving inside a building within the coverage area of a WiFi access point. These targets were monitored from outside the building using a 2.4-GHz passive multistatic receiver, and the data were processed offline to yield range and Doppler information. The results presented show the first through-the-wall (TTW) detections of moving personnel using passive WiFi radar. The measured Doppler shifts agree with those predicted by bistatic theory. Further analysis of the data revealed that the system is limited by the signal-to-interference ratio (SIR), and not the signal-to-noise ratio. We have also shown that a new interference suppression technique based on the CLEAN algorithm can improve the SIR by approximately 19 dB. These encouraging initial findings demonstrate the potential for using passive WiFi radar as a low-cost TTW detection sensor with widespread applicability.

240 citations


Cites background from "Through-the-Wall Radar Imaging"

  • ...BOTH passive radar and through-the-wall (TTW) imaging systems have been the focus of growing interest in recent years [1], [2] for applications in the security and defense industries....

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  • ...These capabilities make TTW RF systems most suitable for applications in covert surveillance, urban warfare, and search and rescue [2]....

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Journal ArticleDOI
TL;DR: A low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces is demonstrated and computational methods and calibration approaches that enable rapid and accurate imaging performance are introduced.
Abstract: We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements of spatially-diverse field patterns, diffraction-limited images of human-sized subjects are reconstructed. The system is driven by a single microwave source swept over a band of frequencies (17.5–26.5 GHz) and switched between a collection of transmit and receive metasurface panels. High fidelity image reconstruction requires a precise model for each field pattern generated by the aperture, as well as the manner in which the field scatters from objects in the scene. This constraint makes scaling of computational imaging systems inherently challenging for electrically large, coherent apertures. To meet the demanding requirements, we introduce computational methods and calibration approaches that enable rapid and accurate imaging performance.

228 citations

Journal ArticleDOI
TL;DR: A multipath model for sensing through walls using radars is derived, which improves the radar system performance by aiding in ameliorating the false positives in the original SAR image, as well as increasing the signal-to-clutter ratio at the target locations, culminating in enhanced behind the wall target detection and localization.
Abstract: We derive a multipath model for sensing through walls using radars. The model considers propagation through a front wall and specular reflections at interior walls in an enclosed room under surveillance. The model is derived such that additional eigenrays can be easily accommodated. A synthetic aperture radar (SAR) system is considered, and stationary or slowly moving targets are assumed. The focused downrange and crossrange locations of multipath ghosts are established and validated using numerical, as well as experimental data. The multipath model permits an implementation of a multipath exploitation algorithm, which associates, as well as maps, each target ghost back to its corresponding true target location. In doing so, the proposed algorithm improves the radar system performance by aiding in ameliorating the false positives in the original SAR image, as well as increasing the signal-to-clutter ratio at the target locations, culminating in enhanced behind the wall target detection and localization.

162 citations

Journal ArticleDOI
TL;DR: An effective wall clutter mitigation approach is proposed for TWRI that does not require knowledge of the background scene nor does it rely on accurate modeling and estimation of wall parameters, and is comparable to that of background subtraction, which requires knowledge of a reference background scene.
Abstract: One of the main challenges in through-the-wall radar imaging (TWRI) is the strong exterior wall returns, which tend to obscure indoor stationary targets, rendering target detection and classification difficult, if not impossible. In this paper, an effective wall clutter mitigation approach is proposed for TWRI that does not require knowledge of the background scene nor does it rely on accurate modeling and estimation of wall parameters. The proposed approach is based on the relative strength of the exterior wall returns compared to behind-wall targets. It applies singular value decomposition to the data matrix constructed from the space-frequency measurements to identify the wall subspace. Orthogonal subspace projection is performed to remove the wall electromagnetic signature from the radar signals. Furthermore, this paper provides an analysis of the wall and target subspace characteristics, demonstrating that both wall and target subspaces can be multidimensional. While the wall subspace depends on the wall type and building material, the target subspace depends on the location of the target, the number of targets in the scene, and the size of the target. Experimental results using simulated and real data demonstrate the effectiveness of the subspace projection method in mitigating wall clutter while preserving the target image. It is shown that the performance of the proposed approach, in terms of the improvement factor of the target-to-clutter ratio, is better than existing approaches and is comparable to that of background subtraction, which requires knowledge of a reference background scene.

137 citations


Cites background from "Through-the-Wall Radar Imaging"

  • ...2355211 rescue missions, behind-wall target detection, and surveillance and reconnaissance in urban environments [1]–[5]....

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Journal ArticleDOI
TL;DR: This work develops effective methods for the reconstruction of stationary scenes, which employ a group sparse CS approach joining wall and target models, which allows suppression of the ghosts and increased signal-to-clutter ratio (SCR) at the target locations.
Abstract: Multipath exploitation and compressive sensing (CS) have both been applied independently to through-the-wall radar imaging (TWRI). Fast and efficient data acquisition is desired in scenarios where multipath effects cannot be neglected. Hence, we combine the two methods to achieve good image reconstruction in multipath environments from few spatial and frequency measurements. Ghost targets appear in the scene primarily due to specular reflections from interior walls and multiple reflections within the front wall. Assuming knowledge of the room geometry, we can invert the multipath model and eliminate ghosts by means of CS. We develop effective methods for the reconstruction of stationary scenes, which employ a group sparse CS approach. Additionally, we separate the target and wall contributions to the image by a sparse reconstruction approach joining wall and target models, which allows suppression of the ghosts and increased signal-to-clutter ratio (SCR) at the target locations. Effectiveness of the proposed approach is demonstrated using both simulated and real data.

130 citations