- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA) - Coimbatore (2018.3.29-2018.3.31)] 2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA) - Analysis and Evaluation of Speckle Filters by Using Polarimetric Synthetic Aperture Radar Data Through Local Statistics
摘要： Speckle noise, a granular noise, occurs in synthetic aperture radar (SAR) data due to the interference of reflected signals with several scatterers in a resolution cell. One of the simplest techniques to suppress speckle noise from polarimetric SAR data is to use local statistics. The Lee filter employs sample mean and variance of pixels of data degraded by speckle noise, which can be multiplicative, additive, or a mixture of both, in a searching window. The refined Lee method utilizes directional windows with local minimum mean square error (LMMSE), which ensures superior maintenance of spatial resolution and features. The Lee–Sigma filter is constructed on the basis of the two-sigma probability, which effectively suppresses the speckle noise. However, insufficiencies were observed in the generation of a biased evaluation, blurring of edges, and suppression of point targets. To eliminate these insufficiencies, the improved Lee–Sigma filter was developed, which employs the minimum mean square error estimate as a priori mean. Thus, an excellent maintenance of point targets and subtle details is displayed. In this study, the Lee, refined Lee, Lee–Sigma, and improved Lee–Sigma filters were evaluated using full polarimetric data. The evaluated results indicated that the improved Lee–Sigma filter performed better than other local statistics filters.
关键词： Speckle noise,Synthetic aperture radar,Minimum mean square error,Polarimetric synthetic aperture radar
更新于2025-09-04 15:30:14
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Unmanned Aerial Vehicle Recognition Based on Clustering by Fast Search and Find of Density Peaks (CFSFDP) with Polarimetric Decomposition
摘要： Unmanned aerial vehicles (UAV) have become vital targets in civilian and military fields. However, the polarization characteristics are rarely studied. This paper studies the polarization property of UAVs via the fusion of three polarimetric decomposition methods. A novel algorithm is presented to classify and recognize UAVs automatically which includes a clustering method proposed in "Science", one of the top journals in academia. Firstly, the selection of the imaging algorithm ensures the quality of the radar images. Secondly, local geometrical structures of UAVs can be extracted based on Pauli, Krogager, and Cameron polarimetric decomposition. Finally, the proposed algorithm with clustering by fast search and find of density peaks (CFSFDP) has been demonstrated to be better than the original methods under the various noise conditions with the fusion of three polarimetric decomposition methods.
关键词： synthetic aperture radar (SAR),unmanned aerial vehicle,inverse synthetic aperture radar (ISAR),man-made targets,clustering methods,polarimetric decomposition
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Backprojection Autofocus of Moving Ships for Synthetic Aperture Radar
摘要： In this paper, we present a backprojection autofocus method to image moving ships in high resolution very precisely. This technique might make an automatic ship classification based on Synthetic Aperture Radar (SAR) images without using additional information from the Automated Identification System (AIS) possible. We use a Constant False Alarm Rate (CFAR) detector to estimate the coarse position of a ship in a preview SAR image. A second high resolution image of the ship is generated by the proposed backprojection autofocus algorithm. Our autofocus estimates the time depending distance between the sensor and every pixel in the SAR image, which includes the rotation and the translation of the ship. This estimated relative distance is used to compute a high quality autofocused SAR image of the considered moving ship.
关键词： radar imaging,Synthetic aperture radar,inverse synthetic aperture radar,autofocus,radar detection,airborne radar
更新于2025-09-04 15:30:14
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Range- and Aperture-dependent Motion Compensation based on Precise Frequency Division and Chirp Scaling for Synthetic Aperture Radar
摘要： The complicated vibrations of the radar sensor, referred to as motion error, generally produce extra range cell migration (RCM) along range direction as well as spectral replicas along azimuth direction, which severely impairs the quality of a focused synthetic aperture radar (SAR) image. This paper concerns the compensation of motion error which is deemed to be range- and aperture-dependent. To this end two pairs of relations: shift-range and angle-frequency, are analyzed. Based on the derived relations, we propose a chirp scaling based range envelope correction (CS-REC) to cope with the range-dependent position shifts (i.e., RCM) and a precise frequency division (PFD) approach to account for the residual aperture-dependent motion error. The proposed algorithm can compensate bulk and complicated motion error completely before range cell migration correction and ensure the focusing-quality of a SAR image without autofocus. Both simulated and real data experiments validate the effectiveness of the proposed algorithm.
关键词： chirp scaling,synthetic aperture radar,Range- and aperture-dependent motion compensation,precise frequency division
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Mechatronics and Automation (ICMA) - Changchun (2018.8.5-2018.8.8)] 2018 IEEE International Conference on Mechatronics and Automation (ICMA) - Status and Trends of the Large Aperture Space Optical Remote Sensor
摘要： Aiming at catching up with the leading countries, this paper gives the right development direction of large aperture optical remote sensor in China. Firstly, we introduced the current situation of large aperture remote sensors using traditional and new imaging systems. Then we summarized the monolithic and deployable remote sensors with full range spectra and high spectrum resolution are the future main development trends. Furthermore, we discussed the key technologies include large aperture lightweight monolithic reflective mirror, active support, precise deployment, co-phasing in orbit, fabrication of large aperture membrane diffractive optics element (DOE) and high performance imaging processing technology of interferometric imaging system. Finally, we conclude China should give more attention to the large aperture monolithic and deployable optical remote sensors, and tackle the key technology in 1.5m~3m aperture monolithic remote sensors at first step and 4m aperture monolithic and the deployable remote sensors next.
关键词： large aperture space optical remote sensor,interference imaging,optical synthetic aperture diffraction imaging,imaging,space deployable segmented imaging
更新于2025-09-04 15:30:14
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Remote Sensing Image Fusion Using Hierarchical Multimodal Probabilistic Latent Semantic Analysis
摘要： The generative semantic nature of probabilistic topic models has recently shown encouraging results within the remote sensing image fusion field when conducting land cover categorization. However, standard topic models have not yet been adapted to the inherent complexity of remotely sensed data, which eventually may limit their resulting performance. In this scenario, this paper presents a new topic-based image fusion framework, specially designed to fuse synthetic aperture radar (SAR) and multispectral imaging (MSI) data for unsupervised land cover categorization tasks. Specifically, we initially propose a hierarchical multi-modal probabilistic latent semantic analysis (HMpLSA) model that takes advantage of two different vocabulary modalities, as well as two different levels of topics, in order to effectively uncover intersensor semantic patterns. Then, we define an SAR and MSI data fusion framework based on HMpLSA in order to perform unsupervised land cover categorization. Our experiments, conducted using three different SAR and MSI data sets, reveal that the proposed approach is able to provide competitive advantages with respect to standard clustering methods and topic models, as well as several multimodal topic model variants available in the literature.
关键词： Image fusion,probabilistic latent semantic analysis (pLSA),synthetic aperture radar (SAR),multispectral imaging (MSI)
更新于2025-09-04 15:30:14
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A Novel Channel Calibration Method for Bistatic ISAR Imaging System
摘要： In practical bistatic inverse synthetic aperture radar (ISAR) imaging systems, the echo signals are modulated by non-ideal amplitude and phase characteristics of the transmitting and receiving channels, which seriously distorts image quality. However, the conventional channel calibration method based on a transponder is not applicable to bistatic ISAR imaging systems, since the baseline of the system is up to hundreds of kilometers. A channel calibration method only using calibration satellite echo information is proposed for the system, with a linear frequency modulation (LFM) waveform. Firstly, echoes of the calibration satellite are collected by tracking the satellite and multi-period echoes are aligned in the time domain, according to the pulse compression result. Then, the signal to noise ratio (SNR) is improved by accumulating multi-period echoes coherently in the time domain and the calibration coef?cient is constructed based on the accumulated signal. Finally, spectrum of the echo signal is multiplied with the calibration coef?cient to compensate the in?uence of channel characteristics. The effectiveness of the proposed method is veri?ed by the simulation experiment with real satellite echoes.
关键词： channel calibration,bistatic inverse synthetic aperture radar,external calibration,coherent accumulation
更新于2025-09-04 15:30:14
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Fabrication of GaOx Confinement Structure for InGaN Light Emitter Applications
摘要： An indium gallium nitride (InGaN) light-emitting diode (LED) with an embedded porous GaN reflector and a current confined aperture is presented in this study. Eight pairs of n+-GaN:Si/GaN in stacked structure are transformed into a conductive, porous GaN/GaN reflector through an electrochemical wet-etching process. Porous GaN layers surrounding the mesa region were transformed into insulating GaOx layers in a reflector structure through a lateral photoelectrochemical (PEC) oxidation process. The electroluminescence emission intensity was localized at the central mesa region by forming the insulating GaOx layers in a reflector structure as a current confinement aperture structure. The PEC-LED structure with a porous GaN reflector and a current-confined aperture surrounded by insulating GaOx layers has the potential for nitride-based resonance cavity light source applications.
关键词： insulating GaOx,current confinement aperture structure,porous GaN,InGaN
更新于2025-09-04 15:30:14
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Coupling Scattering Characteristic Analysis of Dihedral Corner Reflectors in SAR Images
摘要： The scattering mechanisms of dihedral corner reflectors have attracted great attention in the past decades. However, the scattering centers of dihedral corners are not discussed systematically. In this paper, the multi-bouncing scattering mechanism of dihedral corners is analyzed in detail based on the scattering characteristics of polygon plates and ray-tracing technique. Furthermore, the coupling scattering center (CSC) is proposed as a detailed explanation of the multi-bouncing scattering mechanism of dihedral corners and the locations of CSCs in the high-resolution range profile (HRRP) are deduced based on the monostatic-and-bistatic equivalence theorem (MBET). CSCs give a precise description of target structures and can improve the ability of radar target recognition. Finally, simulation results via electromagnetic computation validate the theoretical analysis.
关键词： coupling scattering center (CSC),dihedral corner reflector,Auto Target Recognition (ATR),Synthetic Aperture Radar (SAR)
更新于2025-09-04 15:30:14
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - SAR Image Restoration via a NL Approach Based on the KS Test
摘要： Synthetic Aperture Radar (SAR) image despeckling is still an open issue. Several approaches have been proposed in the last decades. The recently proposed NonLocal approaches are often considered as the state of art of SAR despeckling. The difference between the NL algorithms presented in literature is mainly related to the adopted distance metric between patches and on the rule used for averaging the selected pixels. Within this manuscript a new metric for selecting similar patches is presented. The metric is based on the statistical distribution of the complex noisy image. The Kolmogorov-Smirnov (KS) test is adopted to compare the statistical distribution and to select similar patches. The approach has been tested and validate on real data, showing interesting performances.
关键词： NonLocal Filters,Synthetic Aperture Radar,Speckle
更新于2025-09-04 15:30:14