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Asia-Pacific Microwave Conference

作者： Shuang Liu Shiyong Li Guoqiang Zhao Houjun Sun Beijing Key Laboratory of Millimeter Wave and Terahertz Technology Beijing Institute of Technology

ISBN: (纸本)9781479987689

The single-input multiple-output (SIMO) array based imaging system has been applied for remote sensing and concealed weapon detection. In this paper, comparisons of the back-projection (BP) algorithm and wavenumber domain (ωk) algorithm applied to SIMO imaging are provided both in the near-field case and far-field case. Simulations demonstrate that the BP algorithm performs better in the near-field case. For the ωk algorithm, there would appear deviation and slight defocusing of the target due to the Taylor approximation in the near-field case. In the far-field case, the imaging result of BP algorithm is almost identical with that of ωk algorithm but the former would need more operation time.

关键词： Single input multiple output (SIMO) Wavenumber domain algorithm back-projection algorithm Two dimensional imaging

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Tomography on Continuous Variable Quantum States

Tomography on Continuous Variable Quantum States

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作者： Ludmila Augusta Soares Botelho UNIVERSIDADE FEDERAL DE MINAS GERAIS - UFMG

学位级别：硕士

In this work we have explored few tools in Quantum State Tomography for Continuous Variable Systems. The concept of quantum states in phase space representation is introduced in a simple manner by using a few statistical concepts. Unlike most texts of Quantum information in which the Wigner function for a single mode is often more used, in this text the multi-modes state Wigner function is also developed. Our numerical investigations indicate that the reconstructed method using back-projection add some error due the choice of cutoff frequency, therefore it is necessary to use data post-processing, like the semi-definite programs, which provides sufficient conditions correctly estimate the state. Once the information about the state is recovered, important features such as entanglement can also be investigated.

关键词： Wigner function quadrature continuous variable Gaussian state coherent state squeezed state Fock state single mode state multi mode state homodyne detection tomography Radon transform inverse Radon back-projection algorithm kernel cutoff characteristic function fidelity semi-definite programs SDP entanglement

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On the Time-Domain Airborne SAR Focusing in the Presence of Strong Azimuth Variations of the Squint Angle

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2023年 61卷 1页

作者： Berardino, Paolo Natale, Antonio Esposito, Carmen Lanari, Riccardo Perna, Stefano Inst Elect Sensing Environm Natl Res Council IREA Naples Italy Univ Napoli Parthenope Dipartimento Ingn DI I-80133 Naples Italy

Airborne synthetic aperture radar (SAR) data focusing in the presence of highly variable squint angles is addressed in this work. To do this, a time-domain SAR focusing algorithm has been developed to account for the target-dependent nature of the acquisition squint angle. For comparison purposes, we have considered also a SAR processor based on the use of an azimuth-invariant processing squint angle. Moreover, real data acquired by two different X-band airborne SAR systems have been analyzed. The aims of the work are twofold. First, we show that the adoption of an azimuth-invariant processing squint angle, typically pursued by computationally efficient focusing strategies, may become inappropriate in several airborne missions, which are typically corrupted by motion errors induced by atmospheric turbulence. On the contrary, these problems are circumvented through the developed time-domain focusing strategy, which exploits a target-dependent processing squint angle that is coincident with the acquisition one. Second, we show that the proposed focusing strategy must be properly revised in the case of interferometric processing. In particular, we show that if the (target-dependent) acquisition squint angle is different for the two interferometric channels used, we have to move toward a different focusing paradigm, say, an interferometric focusing solution. This is again based on considering a target-dependent processing squint angle, but for each target, this processing angle should be equal neither to the acquisition squint angle of the "main" acquisition nor to that of the "secondary" one: it must instead lie halfway between them. We prove that this approach is appropriate to obtain high interferometric coherence, and it is suboptimal to separately focus the interferometric channels.

关键词： Airborne synthetic aperture radar (SAR) back-projection algorithm squint

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A New Synthetic Aperture Radar (SAR) Imaging Method Combining Match Filter Imaging and Image Edge Enhancement

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SENSORS 2018年第12期18卷 4133-4133页

作者： Sun, Bing Fang, Chuying Xu, Hailun Gao, Anqi Beihang Univ Sch Elect & Informat Engn Beijing 102200 Peoples R China

In general, synthetic aperture radar (SAR) imaging and image processing are two sequential steps in SAR image processing. Due to the large size of SAR images, most image processing algorithms require image segmentation before processing. However, the existence of speckle noise in SAR images, as well as poor contrast and the uneven distribution of gray values in the same target, make SAR images difficult to segment. In order to facilitate the subsequent processing of SAR images, this paper proposes a new method that combines the back-projection algorithm (BPA) and a first-order gradient operator to enhance the edges of SAR images to overcome image segmentation problems. For complex-valued signals, the gradient operator was applied directly to the imaging process. The experimental results of simulated images and real images validate our proposed method. For the simulated scene, the supervised image segmentation evaluation indexes of our method have more than 1.18%, 11.2% and 11.72% improvement on probabilistic Rand index (PRI), variability index (VI), and global consistency error (GCE). The proposed imaging method will make SAR image segmentation and related applications easier.

关键词： imaging edge detection image segmentation back-projection algorithm differential operation

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Analysis of a Bistatic Ground-Based Synthetic Aperture Radar System and Indoor Experiments

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REMOTE SENSING 2021年第1期13卷 63-63页

作者： Lee, Hoonyol Moon, Jihyun Kangwon Natl Univ Dept Geophys Chunchon 24341 Kangwon Do South Korea

Recent advancement of satellite synthetic aperture radar (SAR) techniques require more sophisticated system configurations such as the use of bistatic antennas or multi-frequencies. A ground-based experiment is a cost-effective and efficient way to evaluate those new configurations especially in the early stage of the system development. In this paper, a ground-based synthetic aperture radar (GB-SAR) system was constructed and operated in a bistatic mode at Ku-band where a receiving antenna (Rx) follows a transmitting antenna (Tx) separated by a baseline B. A new bistatic GB-SAR focusing algorithm was developed by modifying a conventional range-Doppler algorithm (RDA), and its performance has been evaluated by comparing the results with those from a back-projection algorithm (BPA). The results showed good performance of RDA at far range approaching nominal resolutions of 9.4 cm in range and 4.5 cm in azimuth, but limited quality at near range due to the approximation used in RDA. Signals from three trihedral corner reflectors (CR) reduced with increasing B, showing a typical bidirectional scattering behavior of CR. This GB-SAR system will be a testbed for new SAR imaging configurations with variations in antenna positions and target properties.

关键词： bistatic GB-SAR Ku-band back-projection algorithm range-Doppler algorithm

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Particle-filter-based human target tracking in image domain for through-wall imaging radar

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JOURNAL OF ENGINEERING-JOE 2019年第20期2019卷 6549-6553页

作者： Chen, Guohao Cui, Guolong Kong, Lingjiang Guo, Shisheng Cao, Lingxiao Univ Elect Sci & Technol China Sch Informat & Commun Engn Dept Elect Engn Chengdu Sichuan Peoples R China

This study deals with a tracking problem for hidden human targets using time-division multiple-input-multiple-output through-wall imaging radar (TWIR). An efficient image-domain tracking algorithm is proposed. Specifically, the authors first utilise back-projection algorithm and the phase coherence factor (PCF) to obtain multi-frame high quality images. Then a tracking algorithm via amplitude-distribution-based particle filter is proposed. Experimental data validates that this algorithm has a commendable effectiveness for hidden target tracking.

关键词： target tracking ultra wideband radar particle filtering (numerical methods) radar imaging particle-filter-based human target tracking image domain through-wall imaging radar tracking problem hidden human targets time-division multiple-input-multiple-output efficient image-domain tracking algorithm back-projection algorithm phase coherence factor multiframe high quality images amplitude-distribution-based particle filter hidden target tracking

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A Data Standardization and Reconstruction Method for Magnetic Induction Tomography 1

A Data Standardization and Reconstruction Method for Magneti...

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2012 International Conference on Biomaterial and Bioengineering(ICBB 2012)

作者： Qiang Du Baodong Bai Li Ke Institute of Biomedical and Electromagnetic Engineering Shenyang University of Technology

Magnetic induction tomography(MIT) is a biologic tomography technology, which is to obtain the conductivity distribution by detecting the data on the boundary of the imaging area based on the eddy current principle. The small impedance difference between biological tissues makes the eddy current weak, and it leads to a direct effect on the biological impedance measurement and imaging sensitivity. A measured data standardization method is presented in this paper for enhancing the measured data sensitivity, and combined with the back-projection reconstruction algorithm to get reconstruction image. It is applied to a variety of measurement and the simulation experiment based on the calculation results of finite-element methods. The reconstructed images indicate that the method can improve the image resolution and sensitivity, and which provides an effective data standardization and reconstruction algorithm for the magnetic induction tomography.

关键词： Magnetic Induction Tomography(MIT) Reconstruction algorithm back-projection algorithm Standardization Method

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Wide-field circular SAR imaging: 2D imaging results for simulation data

Wide-field circular SAR imaging: 2D imaging results for simu...

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International Conference on Recent Advances in Space Technologies

作者： Sevket Demirci Enes Yigit Caner Ozdemir The Department of Electrical and Electronics Engineering Mersin University

ISBN: (纸本)9781467363952

Circular synthetic aperture radar (CSAR) systems collect data over circular trajectories. Due to the curved, wide-angle geometry, focusing of CSAR data is known to be a difficult process. Additionally, when the spatial extent of the scene to be imaged is a significant fraction of the SAR path radius (i.e. in wide-field scenarios), layover phenomenon occurs which may further limit successful imaging of targets. In this paper, to characterize these layover effects, various simulation results for wide-field single-pass CSAR geometry are presented under point scattering assumption.

关键词： Circular synthetic aperutre radar (CSAR) Synthetic aperture radar (SAR) Near-field scattering back-projection algorithm

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Spaceborne-airborne SAR interferometry based on BP algorithm

Spaceborne-airborne SAR interferometry based on BP algorithm

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IET International Radar Conference 2015

作者： Xinxin Tang Xiaoling Zhang Shunjun Wei Jianing Liu University of Electronic Science and Technology of China

ISBN: (纸本)9781510822023

In this paper, an interferometric synthetic aperture radar (InSAR) technique based on spaceborne-airborne bistatic SAR interferometry (SA-BiInSAR) is presented, in which the transmitter and receivers are mounted on the spacecraft and aircraft respectively. Due to the separated transmitter and receivers, and also the common non-ideal trajectory of the airborne received platform, the conventional frequency-domain SAR imaging approaches, such as range-doppler algorithm and chirp scaling algorithm, are very difficult for SA-BiInSAR imaging processing directly. To obtain high-quality of SA-BiInSAR image formation and interferogram, in this paper a back-projection algorithm, based on time-domain coherent integration of target signals, is developed for SA-BiInSAR imaging and phase extraction in the case of non-ideal trajectory. In this scheme, the echoes of SA-BiInSAR master and slave channels are projected into the same imaging space, and the interferometric phase of SA-BiInSAR is derived utilizing the principle of BP algorithm. Simulation results demonstrate the performances of SA-BiInSAR, and verify the effectiveness of the presented BP algorithm for SA-BiInSAR image formation and phase extraction in the case of non-ideal trajectory.

关键词： SA-BiInSAR SAR Interferometry back-projection algorithm Interferometric phase Synthetic aperture radar projection algorithms Receivers algorithms interferometry interference pattern Transmitters Image formation trajectory Spacecraft

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3D Contour Reconstruction of Convex Object Based on Fluorescence Molecular Tomography

3D Contour Reconstruction of Convex Object Based on Fluoresc...

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第23届过程控制会议

作者： Li Qi-An Zhou Yun Li Yue School of Information and Control Engineering Liaoning Shihua University Fushun 113001

Fluorescence molecular tomography (FMT) based on CCD is developing rapidly these years. In order to get the density of forward model of fluorophore, we need to reconstruct the contour of target object. A new three-dimensional modeling method based on CT back-projection algorithm with few-views is proposed in this paper. Binary pictures is captured by 180° scanning with the help of CCD camera, and then filtering and fitting is operated. Ultimately, surface fitting in three-dimensional modeling is completed by least-squares method. Traditional method of 3D contour reconstruction needs to scan for 360° while this new method needs only 180°, and modeling could be completed even if the projection angle is fewer. Moreover, this method provide a reference to combine FMT and CT into one system.

关键词： FMT back-projection algorithm Least-squares method Three-dimensional modeling

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