scholarly journals Comparison of Raw Data-Based and Complex Image-Based Sparse SAR Imaging Methods

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 320 ◽  
Author(s):  
Zhilin Xu ◽  
Bingchen Zhang ◽  
Hui Bi ◽  
Chenyang Wu ◽  
Zhonghao Wei
Keyword(s):  
Imaging Method ◽  
Signal Ratio ◽  
Raw Data ◽  
Imaging Model ◽  
Complex Image ◽  
Sar Imaging ◽  
Imaging Performance ◽  
The Relationship ◽  
Suppress Noise ◽  
Image Performance

Sparse signal processing has already been introduced to synthetic aperture radar (SAR), which shows potential in improving imaging performance based on raw data or a complex image. In this paper, the relationship between a raw data-based sparse SAR imaging method (RD-SIM) and a complex image-based sparse SAR imaging method (CI-SIM) is compared and analyzed in detail, which is important to select appropriate algorithms in different cases. It is found that they are equivalent when the raw data is fully sampled. Both of them can effectively suppress noise and sidelobes, and hence improve the image performance compared with a matched filtering (MF) method. In addition, the target-to-background ratio (TBR) or azimuth ambiguity-to-signal ratio (AASR) performance indicators of RD-SIM are superior to those of CI-SIM in down-sampling data-based imaging, nonuniform displace phase center sampling, and sparse SAR imaging model-based azimuth ambiguity suppression.

scholarly journals Three-Dimensional Imaging Method for Array ISAR Based on Sparse Bayesian Inference

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3563
Author(s):  
Zekun Jiao ◽  
Chibiao Ding ◽  
Longyong Chen ◽  
Fubo Zhang
Keyword(s):  
Bayesian Inference ◽  
3D Imaging ◽  
Three Dimensional ◽  
Super Resolution ◽  
Information Criterion ◽  
Radar Data ◽  
Imaging Method ◽  
Model Order Selection ◽  
Imaging Model ◽  
Imaging Performance

The problem of synthesis scatterers in inverse synthetic aperture radar (ISAR) make it difficult to realize high-resolution three-dimensional (3D) imaging. Radar array provides an available solution to this problem, but the resolution is restricted by limited aperture size and number of antennas, leading to deterioration of the 3D imaging performance. To solve these problems, we propose a novel 3D imaging method with an array ISAR system based on sparse Bayesian inference. First, the 3D imaging model using a sparse linear array is introduced. Then the elastic net estimation and Bayesian information criterion are introduced to fulfill model order selection automatically. Finally, the sparse Bayesian inference is adopted to realize super-resolution imaging and to get the 3D image of target of interest. The proposed method is used to process real radar data of a Ku band array ISAR system. The results show that the proposed method can effectively solve the problem of synthesis scatterers and realize super-resolution 3D imaging, which verify the practicality of our proposed method.

scholarly journals Efficient Parameter Estimation for Sparse SAR Imaging Based on Complex Image and Azimuth-Range Decouple

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4549
Author(s):  
Mingqian Liu ◽  
Bingchen Zhang ◽  
Zhongqiu Xu ◽  
Yirong Wu
Keyword(s):  
Parameter Estimation ◽  
Large Scale ◽  
Regularization Parameter ◽  
Estimation Method ◽  
Imaging Method ◽  
Adaptive Parameter ◽  
Processing Theory ◽  
Complex Image ◽  
Sar Imaging ◽  
Observation Matrix

Sparse signal processing theory has been applied to synthetic aperture radar (SAR) imaging. In compressive sensing (CS), the sparsity is usually considered as a known parameter. However, it is unknown practically. For many functions of CS, we need to know this parameter. Therefore, the estimation of sparsity is crucial for sparse SAR imaging. The sparsity is determined by the size of regularization parameter. Several methods have been presented for automatically estimating the regularization parameter, and have been applied to sparse SAR imaging. However, these methods are deduced based on an observation matrix, which will entail huge computational and memory costs. In this paper, to enhance the computational efficiency, an efficient adaptive parameter estimation method for sparse SAR imaging is proposed. The complex image-based sparse SAR imaging method only considers the threshold operation of the complex image, which can reduce the computational costs significantly. By utilizing this feature, the parameter is pre-estimated based on a complex image. In order to estimate the sparsity accurately, adaptive parameter estimation is then processed in the raw data domain, combining with the pre-estimated parameter and azimuth-range decouple operators. The proposed method can reduce the computational complexity from a quadratic square order to a linear logarithm order, which can be used in the large-scale scene. Simulated and Gaofen-3 SAR data processing results demonstrate the validity of the proposed method.

scholarly journals Geosynchronous Spaceborne-Airborne Bistatic Moving Target Indication System: Performance Analysis and Configuration Design

2020 ◽  
Vol 12 (11) ◽  
pp. 1810
Author(s):  
Xichao Dong ◽  
Chang Cui ◽  
Yuanhao Li ◽  
Cheng Hu
Keyword(s):  
Design Method ◽  
Configuration Design ◽  
Moving Target ◽  
Maximum Output ◽  
Sar Imaging ◽  
Long Time ◽  
Bistatic Synthetic Aperture Radar ◽  
Indication System ◽  
Imaging Performance ◽  
The Relationship

Geosynchronous spaceborne-airborne bistatic synthetic aperture radar (GEO SA-BSAR), consisting of GEO transmitter and airborne receiver, has stable coverage for a long time and benefits moving target detection. However, the performance of GEO SA-BSAR moving target indication (MTI) system varies widely between bistatic configurations. The traditional configuration design for GEO SA-BSAR system only considers the imaging performance, which may cause the poor MTI performance. In this paper, we propose a bistatic configuration design method to jointly optimize the MTI and SAR imaging performance for GEO SA-BSAR MTI system. The relationship between the MTI performance and bistatic configuration parameters is derived analytically and analyzed based on the maximum output signal to clutter and noise ratio (SCNR) criterion. Then, the MTI performance and SAR imaging performance are jointly considered to model the configuration design problem as a multi-objective optimization problem under the constrained condition. Finally, the optimal configuration for GEO SA-BSAR MTI system is given.

scholarly journals End-to-End SAR Deep Learning Imaging Method Based on Sparse Optimization

2021 ◽  
Vol 13 (21) ◽  
pp. 4429
Author(s):  
Siyuan Zhao ◽  
Jiacheng Ni ◽  
Jia Liang ◽  
Shichao Xiong ◽  
Ying Luo
Keyword(s):  
Deep Learning ◽  
Sparse Optimization ◽  
Complex Signal ◽  
Imaging Method ◽  
Two Dimensional ◽  
Imaging Algorithm ◽  
Imaging Model ◽  
Sar Imaging ◽  
Observation Matrix ◽  
End To End

Synthetic aperture radar (SAR) imaging has developed rapidly in recent years. Although the traditional sparse optimization imaging algorithm has achieved effective results, its shortcomings are slow imaging speed, large number of parameters, and high computational complexity. To solve the above problems, an end-to-end SAR deep learning imaging algorithm is proposed. Based on the existing SAR sparse imaging algorithm, the SAR imaging model is first rewritten to the SAR complex signal form based on the real-value model. Second, instead of arranging the two-dimensional echo data into a vector to continuously construct an observation matrix, the algorithm only derives the neural network imaging model based on the iteration soft threshold algorithm (ISTA) sparse algorithm in the two-dimensional data domain, and then reconstructs the observation scene through the superposition and expansion of the multi-layer network. Finally, through the experiment of simulation data and measured data of the three targets, it is verified that our algorithm is superior to the traditional sparse algorithm in terms of imaging quality, imaging time, and the number of parameters.

scholarly journals The relationship between the Municipal Human Development Index and rates of violent death in Brazilian Federal Units

2016 ◽  
Vol 26 (2) ◽  
pp. 211 ◽  
Author(s):  
Lylla Winzer
Keyword(s):  
Human Development ◽  
Human Development Index ◽  
Violent Death ◽  
Raw Data ◽  
Development Index ◽  
The Relationship

Because countries with the highest Human Development Index (HDI) have low rates of violence, it is common to assume that the increase of HDI may correspond with lower rates of violence in a country. This study examined the relationship between the Municipal Human Development Index (MHDI) and violent deaths in the Brazilian States between 1991 and 2010. We tested whether the increase of MHDI indirectly reduces violence or whether the reduction of violence predicts higher MHDI in later years. The raw data were obtained from three sources online, Atlasbrasil, IPEAdata and Map of violence. The analyses do not support the assumption that the increase of MHDI leads to a reduced level of violence. However, there are indications that the decrease of homicides over the years results in improved MHDI rates in 2010. The results suggest that taking measures aimed at development does not automatically imply a lower level of violence, but fi ghting against violence may increase MHDI.

TOPS Mode Raw Data Generation From Wide-Beam SAR Imaging Modes

2012 ◽  
Vol 9 (4) ◽  
pp. 720-724 ◽  
Author(s):  
Wei Xu ◽  
Yunkai Deng ◽  
Fan Feng ◽  
Yue Liu ◽  
Guangting Li
Keyword(s):  
Data Generation ◽  
Raw Data ◽  
Wide Beam ◽  
Sar Imaging

Leadership for the Christian Empire: Emperors and Bishops in theEcclesiastical Historyof Philostorgius

2018 ◽  
Vol 87 (3) ◽  
pp. 684-717
Author(s):  
Anna Lankina
Keyword(s):  
Late Antiquity ◽  
Early Christianity ◽  
Fifth Century ◽  
Raw Data ◽  
Ecclesiastical History ◽  
Theory Of History ◽  
The Relationship

The fifth-centuryEcclesiastical Historyof Philostorgius is an unusual example of a surviving minority source. Although scholars have mined his work for raw data on events between 320 and 425c.e., in contrast to other contemporary ecclesiastical historians, Philostorgius has received little attention. His work has suffered derision, being seen as nothing more than “Arian” polemic and thus as more partisan than its pro-Nicene counterparts. This essay analyzes Philostorgius's role as one of many competitive voices participating in the composition of historical works for the elite readership of Constantinople in the fifth century. Philostorgius'sEcclesiastical Historyconstituted an integral part of the historiography of late antiquity and early Christianity. His representation of the relationship between bishops and emperors reveals a distinctive theory of history which informs his entire work.

A SAR Imaging Method for Walking Human Based on m ωka-FrFT-mmGLRT

2021 ◽  
pp. 1-12
Author(s):  
Shuliang Gui ◽  
Jin Li ◽  
Yue Yang ◽  
Feng Zuo ◽  
Yiming Pi
Keyword(s):  
Imaging Method ◽  
Sar Imaging
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