Article
Geochemistry & Geophysics
Xinhua Mao, Tianyue Shi, Ronghui Zhan, Yu-Dong Zhang, Daiyin Zhu
Summary: This article presents a new interpretation of the polar format algorithm for general bistatic spotlight synthetic aperture radar imaging, analyzing the roles of range and azimuth resampling on residual 2-D phase error and proposing a structure-aided 2-D autofocus approach to improve accuracy. Experimental results demonstrate the effectiveness of the proposed approach.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2021)
Article
Geochemistry & Geophysics
Hongyang An, Junjie Wu, Kah Chan Teh, Zhichao Sun, Jianyu Yang
Summary: This study proposes a new method to recover the unambiguous image of GEO-SA-BiSAR by establishing an accurate echo model and introducing a modified alternating direction method of multipliers (M-ADMM). Additionally, a multi-channel M-ADMM method combining recovery theory and multireceiving information is proposed to handle the severe sub-Nyquist sampling echo of GEO-SA-BiSAR. Simulation results show high computational efficiency and reduced number of receiving channels compared to traditional methods.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Geography, Physical
Michael Recla, Michael Schmitt
Summary: Deep learning-based single-image height estimation is of great importance in remote sensing, and can be applied to synthetic aperture radar (SAR) data with good transferability across different imaging modes and parameters.
ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING
(2022)
Article
Environmental Sciences
Hanqing Zhang, Yun Lin, Fei Teng, Wen Hong
Summary: This paper investigates the problem of obtaining dense 3D reconstruction from airborne multiaspect synthetic aperture radar (SAR) image sequences. To address the issue of anisotropic scatters, a probabilistic 3D reconstruction method is proposed based on jointly estimating the pixel's height and degree of anisotropy.
Article
Engineering, Electrical & Electronic
Manfred Zink, Alberto Moreira, Irena Hajnsek, Paola Rizzoli, Markus Bachmann, Ralph Kahle, Thomas Fritz, Martin Huber, Gerhard Krieger, Marie Lachaise, Michele Martone, Edith Maurer, Birgit Wessel
Summary: The TanDEM-X mission, launched in 2010, aimed to provide a global Digital Elevation Model with unprecedented accuracy using a formation flying radar system. In addition to DEM data, TanDEM-X also has unique capabilities that support various scientific experiments. Despite the completion of most mission objectives, the mission continues to focus on monitoring ongoing changes in Earth's topography.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2021)
Article
Environmental Sciences
Yi Li, Wenchao Li, Junjie Wu, Zhichao Sun, Huarui Sun, Jianyu Yang
Summary: This paper proposes a method for estimating and compensating the three-dimensional motion trajectory error of bistatic synthetic aperture radar (BiSAR), which solves the estimation of Doppler error and three-dimensional trajectory error through time-frequency analysis and least squares method, resulting in a clear BiSAR image.
Article
Engineering, Electrical & Electronic
Simon H. Yueh, Rashmi Shah, Xiaolan Xu, Bryan Stiles, Xavier Bosch-Lluis
Summary: The study analyzed the spaceborne aperture radar (SAR) technique based on a combination of signals from the United States Navy's Mobile User Objective System and P-hand signals of opportunity with a sparse array of receivers at low earth orbits. The design focused on forward-looking geometry near the specular direction to achieve high surface reflectivity and adequate signal-to-noise ratio. Utilizing a sparse array sharpened the resolution, reduced ambiguity, and showed promise for high-resolution remote sensing of land surfaces.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2021)
Article
Geochemistry & Geophysics
Haoyu Lin, Yunkai Deng, Heng Zhang, Jili Wang, Da Liang, Tingzhu Fang, Robert Wang
Summary: This article presents a method embedded into the focusing procedure to estimate and remove ionospheric effects on spaceborne BiSAR systems. The effectiveness of the proposed method is verified through simulations.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Environmental Sciences
Da Liang, Heng Zhang, Yonghua Cai, Kaiyu Liu, Ke Zhang
Summary: This paper addresses the issue of phase synchronization in bistatic synthetic aperture radar systems, proposing an advanced scheme based on coherent integration and waveform diversity. With the proposed scheme, the accuracy of phase synchronization can reach 1 degree, demonstrating its effectiveness through simulation experiments.
Article
Environmental Sciences
Zhichao Sun, Tianfu Chen, Huarui Sun, Junjie Wu, Zheng Lu, Zhongyu Li, Hongyang An, Jianyu Yang
Summary: This paper investigates the accurate focusing method for GEO-LEO BiSAR in sliding-spotlight mode. By proposing a new bistatic range model and a frequency-domain imaging method, the problems of curved trajectory and 'stop-and-go' assumption error can be addressed. The effectiveness of the proposed method is validated using simulated data and real data from an equivalent BiSAR experiment.
Article
Environmental Sciences
Jingwen Mou, Yu Wang, Jun Hong, Yachao Wang, Aichun Wang, Shiyu Sun, Guikun Liu
Summary: LuTan-1 (LT-1) is a bistatic synthetic aperture radar (BiSAR) system consisting of two identical L-band SAR satellites. This research establishes geometric calibration models for both SARs and demonstrates the high-precision geolocation accuracy of LT-1 in bistatic mode.
Article
Geochemistry & Geophysics
Yonghua Cai, Junfeng Li, Qingyue Yang, Da Liang, Kaiyu Liu, Heng Zhang, Pingping Lu, Robert Wang
Summary: The innovative BiSAR mission LT-1 uses a noninterrupted synchronization scheme to achieve high-precision phase synchronization. This paper presents the effect of radio frequency interference (RFI) on the synchronization phase and proposes a novel pulse-compression-based notch (PCN) method to eliminate RFI-induced phase errors. Experimental results validate the effectiveness of the proposed method.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Geochemistry & Geophysics
Ruiqing Song, Jicang Wu, Xinyou Song, Tao Li, Lei Zhang
Summary: With the use of new-generation synthetic aperture radar (SAR) satellites with well-controlled orbits and a more accurate timing system, the ability for high-precision geolocation has been confirmed using radar reflectors. This study implemented SAR absolute and differential geolocation methods to determine the coordinates of corner reflectors (CRs) and multidirectional dihedral reflectors (MDRs). Experimental results showed that decimeter- or even centimeter-level positioning accuracy can be achieved using SAR stereo geolocation based on multiaspect SAR acquisitions from RadarSAT-2 (RS-2), COSMO-SkyMed (CSK), Sentinel-1 (S1), and TerraSAR-X (TSX).
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2023)
Article
Geochemistry & Geophysics
Qing Yang, Zhongyu Li, Junao Li, Yahui Wang, Jie Long, Junjie Wu, Yiming Pi, Jianyu Yang
Summary: To address the imaging problem of ship targets in BiSAR under the disturbance of sea waves, this article proposes a distortion-free 3-D image reconstruction method. By analyzing parameters such as bistatic range, Doppler centroid, and Doppler frequency rate, a 3-D domain is constructed to separate scatterers of the ship target's 2-D echoes. By mapping to the local Cartesian coordinate and selecting the rotation parameters with the highest similarity, the image distortion caused by the unknown projection plane is removed, enabling distortion-free 3-D image reconstruction of ship targets in the local Cartesian coordinate.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Engineering, Electrical & Electronic
Paola Rizzoli, Luca Dell'Amore, Jose-Luis Bueso-Bello, Nicola Gollin, Daniel Carcereri, Michele Martone
Summary: This article aims to assess the impact of different decorrelation sources in detail and provide a practical procedure for accurately calculating the volume decorrelation from TanDEM-X bistatic data. By analyzing factors such as noise equivalent sigma naught, backscatter, and quantization rate, we provide corresponding numerical tables and polynomial coefficients for calculating the decorrelation in coherence.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2022)
Article
Geochemistry & Geophysics
Chuang Li, Heng Zhang, Yunkai Deng, Robert Wang, Kaiyu Liu, Dacheng Liu, Guodong Jin, Yanyan Zhang
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2020)
Article
Chemistry, Analytical
Yuanbo Jiao, Da Liang, Kaiyu Liu, Yafeng Chen, Huaizu Wang, Robert Wang
Article
Environmental Sciences
Pengfei Zhao, Yunkai Deng, Wei Wang, Dacheng Liu, Robert Wang
Article
Environmental Sciences
Yao Gao, Xiuqing Liu, Wentao Hou, Yonghui Han, Robert Wang, Heng Zhang
Summary: This study analyzed the characteristics of saline soil in extremely arid regions using dual-band quadrature-polarimetric SAR images, discussed potential relationships between polarimetric parameters and salinity, and established a regression model for monitoring salt content.
Article
Environmental Sciences
Rong Yang, Robert Wang, Yunkai Deng, Xiaoxue Jia, Heng Zhang
Summary: The random cropping data augmentation method is widely used to expand the dataset scale and enhance model robustness, but directly introducing it into training of CNN-based SAR image ship detector may introduce gradient noise and hurt detection performance. A training method based on feature map mask is proposed to effectively eliminate gradient noise, significantly improve detection performance, and without increasing inference cost.
Article
Environmental Sciences
Yanyan Zhang, Sheng Chang, Robert Wang, Peng Li, Yongwei Zhang, Yunkai Deng
Summary: This paper proposes a spaceborne weighted amplitude modulation full-polarimetric SAR system, which can effectively suppress the azimuth ambiguity of hybrid quad-pol SAR.
Article
Environmental Sciences
Haoyu Lin, Yunkai Deng, Heng Zhang, Dacheng Liu, Da Liang, Tingzhu Fang, Robert Wang
Summary: This paper investigates the impacts of two methods for preprocessing dual-channel radar signals in terms of system performance and imaging quality in the LuTan-1 mission. A quantitative comparison is provided.
Article
Environmental Sciences
Wentao Hou, Fengjun Zhao, Xiuqing Liu, Dacheng Liu, Yonghui Han, Yao Gao, Robert Wang
Summary: This paper proposes two new calibration schemes that can simultaneously estimate traditional distortion parameters and amplitude/phase coefficients, addressing the inconsistency issue between measured scattering vectors of different corner reflectors. Simulation and measured data results demonstrate the accuracy of these schemes in estimating the distortion parameters of hybrid compact polarimetric SAR systems.
Article
Environmental Sciences
Hongying Jia, Yingjie Wang, Daqing Ge, Yunkai Deng, Robert Wang
Summary: In this paper, a systematic workflow for landslide study using Interferometric Synthetic Aperture Radar (InSAR) technique is designed. The workflow is applied to the Xiaojiang River Basin, China, and successfully detects new landslides and expansion of existing landslide boundaries. A Total Least Squares-Kalman Filter-based approach is presented for spatial-temporal pattern analysis of a detected landslide. The study provides insights into landslide characteristics and dynamic evolution.
Article
Environmental Sciences
Yanyan Zhang, Fei Zhao, Sheng Chang, Mingliang Liu, Robert Wang
Summary: Due to the rough surface of the Moon, there is a controversy over the existence of water ice in the lunar permanently shadowed regions (PSRs) with a high circular polarization ratio (CPR). To further detect water ice on the Moon, an innovative design method for the spaceborne synthetic aperture radar (SAR) system is proposed. The results of simulation experiments demonstrate the potential of the presented SAR design method for lunar water ice exploration.
Article
Environmental Sciences
Congrui Yang, Fengjun Zhao, Chunle Wang, Mengmeng Wang, Xiuqing Liu, Robert Wang
Summary: This article proposes a novel topography retrieval algorithm based on the Lambertian backscatter model using PolSAR data, which improves the vertical precision of DEM generation. Experimental results show that PolSAR data can be used as a reliable information source for DEM fusion under certain conditions.
Article
Environmental Sciences
Yonghua Cai, Robert Wang, Weidong Yu, Da Liang, Kaiyu Liu, Heng Zhang, Yafeng Chen
Summary: In this study, a phase denoising approach based on compressive sensing is proposed to improve the accuracy of synchronization phase in the bistatic synthetic aperture radar system. The approach eliminates the noise in the synchronization compensation phase through maximum a posteriori estimation, achieving higher phase synchronization accuracy.
Article
Environmental Sciences
Zongxiang Xu, Pingping Lu, Yonghua Cai, Junfeng Li, Tianyuan Yang, Yirong Wu, Robert Wang
Summary: Azimuth multichannel (AMC) technology is widely used in synthetic aperture radar (SAR) satellites for high-resolution wide-swath (HRWS) imaging. However, channel imbalance can negatively impact the azimuth reconstruction spectrum and degrade image quality. This paper proposes a channel imbalance estimation method based on minimizing the sum of the sub-band norm (MSSBN) for the reconstructed azimuth spectrum. Experimental results with simulated and actual SAR data validate the accuracy and efficiency of the proposed algorithm.
Article
Environmental Sciences
Zongxiang Xu, Pingping Lu, Yonghua Cai, Yirong Wu, Robert Wang
Summary: The LuTan-1(LT-1) is an important piece of civil infrastructure in China, providing extensive applications such as surface deformation monitoring and topographic mapping. The LT-1 system uses the dual receiving antenna (DRA) imaging mode to achieve high-resolution and wide-swath observation abilities. However, amplitude and phase errors between channels affect the final imaging quality. In this paper, an advanced channel consistency correction method is proposed and experimental results show its effectiveness.
Article
Environmental Sciences
Yonghui Han, Pingping Lu, Wentao Hou, Yao Gao, Robert Wang
Summary: During the process of the airborne SAR system, platform attitude deflection occurs and affects the calibration accuracy. This paper proposes a novel point target compensation method based on electromagnetic wave reflection theory, which outperforms the conventional POA method in terms of reliability.
