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Reverse backprojection algorithm for the Accurate Generation of SAR Raw Data of Natural Scenes

IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2017年第11期14卷 2072-2076页

作者： Li, Dexin Rodriguez-Cassola, Marc Prats-Iraola, Pau Wu, Manqing Moreira, Alberto Natl Univ Def Technol Inst Space Elect & Informat Technol Changsha 410073 Hunan Peoples R China German Aerosp Ctr DLR Microwaves & Radar Inst D-82234 Wessling Germany

Future synthetic aperture radar (SAR) mission concepts often rely on locally nonlinear (e.g., high orbits and bistatic) surveys or acquisition schemes. The simulation of the raw data of natural scenes as acquired by future systems appears as one powerful tool in order to understand the particularities of these systems and assess the impact of system and propagation errors on their performance. We put forward, in this letter, a new formulation of the reverse backprojection algorithm for the accurate simulation of raw data of natural surfaces. In particular, the algorithm is perfectly suited to accommodate any kind (1-D/2-D) of temporal and spatial variation, e.g., in observation geometry, acquisition strategy, or atmospheric propagation. The algorithm is analyzed with respect to its SAR image formation sibling, and tested under different simulation scenarios. We expect the reverse backprojection algorithm to play a relevant role in the simulation of future geosynchronous and multistatic SAR missions.

关键词： Azimuth variation backprojection algorithm geosynchronous (GEO) SAR raw data simulation synthetic aperture radar (SAR) terrain observation with progressive scan (TOPS) tropospheric propagation

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An Improved Ultrahigh-Resolution Stepped-Frequency Spaceborne SAR Imaging algorithm

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2024年 17卷 3742-3754页

作者： Li, Zhe Ding, Zegang Zhang, Tianyi Li, Linghao Li, Han Dong, Zehua Zheng, Pengnan Beijing Inst Technol Sch Informat & Elect Radar Res Lab Beijing 100081 Peoples R China Beijing Inst Technol Sch Informat & Elect Beijing Key Lab Embedded Real Time Informat Proc T Beijing 100081 Peoples R China Beijing Inst Technol Chongqing Innovat Ctr Chongqing 401331 Peoples R China

Frequency stepping is a widely used technique for ultrahigh-resolution synthetic aperture radar (SAR). Although reducing the burden of hardware, this technique increases the complexity of imaging algorithms due to the intersubband time offsets and intersubband errors of delay, amplitude, and phase. To address the above problems, an improved ultrahigh-resolution stepped-frequency spaceborne SAR imaging algorithm is proposed in this article. By generating subband images individually, performing intersubband error estimation based on primary points, and then synthesizing the subband images in the imaging domain, the proposed algorithm effectively avoids the problem of time offsets and significantly improves intersubband error compensation accuracy benefiting from the high SNR in the imaging domain. Besides, considering the characteristics of nonideal factors in frequency-stepped SAR, a series of error compensation methods aiming at stop-and-go approximation, ionospheric error, and tropospheric delay are integrated to the proposed algorithm. The effectiveness of the proposed algorithms is verified via computer simulations, and real data experiments are also conducted based on both an X-band spaceborne SAR system, Taijing 4-01, and a Ka-band spaceborne SAR system, Luojia 2-01.

关键词： backprojection algorithm stepped-frequency synthetic aperture radar (SAR) ultrahigh-resolution imaging

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Deep learning aided determination of the optimal number of detectors for photoacoustic tomography

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BIOMEDICAL PHYSICS & ENGINEERING EXPRESS 2025年第2期11卷 025029-025029页

作者： Mondal, Sudeep Paul, Subhadip Singh, Navjot Warbal, Pankaj Khanam, Zartab Saha, Ratan K. Indian Inst Informat Technol Allahabad Dept Appl Sci Prayagraj 211015 India Indian Inst Informat Technol Allahabad Dept Informat Technol Prayagraj 211015 India

Photoacoustic tomography (PAT) is a non-destructive, non-ionizing, and rapidly expanding hybrid biomedical imaging technique, yet it faces challenges in obtaining clear images due to limited data from detectors or angles. As a result, the methodology suffers from significant streak artifacts and low-quality images. The integration of deep learning (DL), specifically convolutional neural networks (CNNs), has recently demonstrated powerful performance in various fields of PAT. This work introduces a post-processing-based CNN architecture named residual-dense UNet (RDUNet) to address the stride artifacts in reconstructed PA images. The framework adopts the benefits of residual and dense blocks to form high-resolution reconstructed images. The network is trained with two different types of datasets to learn the relationship between the reconstructed images and their corresponding ground truths (GTs). In the first protocol, RDUNet (identified as RDUNet I) underwent training on heterogeneous simulated images featuring three distinct phantom types. Subsequently, in the second protocol, RDUNet (referred to as RDUNet II) was trained on a heterogeneous composition of 81% simulated data and 19% experimental data. The motivation behind this is to allow the network to adapt to diverse experimental challenges. The RDUNet algorithm was validated by performing numerical and experimental studies involving single-disk, T-shape, and vasculature phantoms. The performance of this protocol was compared with the famous backprojection (BP) and the traditional UNet algorithms. This study shows that RDUNet can substantially reduce the number of detectors from 100 to 25 for simulated testing images and 30 for experimental scenarios.

关键词： photoacoustic tomography image reconstruction backprojection algorithm deep learning convolutional neural networks

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Translational X-Ray Tomographic Approach to Narrow-Angle Scanning of Objects

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RUSSIAN PHYSICS JOURNAL 2020年第3期63卷 345-352页

作者： Ozdiev, A. H. Lazarev, S., V Natl Res Tomsk Polytech Univ Tomsk Russia

An X-ray tomographic scanning method is proposed based on a combination of the angular and translational approaches. The reconstruction algorithms have been used for simple geometric primitives like the twodimensional Shepp-Logan phantom (standard test specimen) and a specimen in a tomographic experiment. The specimens were reconstructed using rotational, translational, and combined limited-angle tomographic scanning. The applicability and the advantages of the proposed approach have been demonstrated compared to other standard scanning approaches. In addition, it is shown that the proposed approach allows 2D and 3D objects to be reconstructed quickly and efficiently. The quality of visualization is a function of the number of angular and translational positions that determine the experimental scanning time and must be selected individually for each physical object to be scanned. This approach provides a fast and informative analysis of various objects in case of failure of standard approaches.

关键词： X-ray tomography backprojection algorithm tomographic scanning trajectory nondestructive testing

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PROCESSING OF SPACEBORNE HIGH-RESOLUTION SAR DATA WITH CURVED ORBIT 39

PROCESSING OF SPACEBORNE HIGH-RESOLUTION SAR DATA WITH CURVE...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Liang, Da Yu, Weidong Zhang, Heng Zhang, Lei Fan, Huaitao Wang, Robert Chinese Acad Sci Inst Elect Beijing 100190 Peoples R China Univ Chinese Acad Sci Beijing 100190 Peoples R China

ISBN: (纸本)9781538691540

A novel imaging algorithm is presented in this paper for focusing the very-high resolution spaceborne synthetic aperture radar (SAR) data of spotlight mode. First, the first step of two-steps processing approach (TSPA) is used to get a high azimuth sampling rate which is higher than PRF for the raw data. Then, the "fast-time" effect of stop-and-go approximation is corrected in 2-D frequency domain. Finally, the backprojection algorithm (BPA) is used to correct the error introduced by the curved orbit and the "slow-time" effect of stopand-go approximation. The simulation results confirm that the proposed method has good performance. The spaceborne SAR data acquired by Gaofen-3 SAR systems demonstrate the feasibility of the proposed method.

关键词： synthetic aperture radar spotlight two-steps processing backprojection algorithm

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Fault-Tolerant Architecture for On-board Dual-Core Synthetic-Aperture Radar Imaging 15th

Fault-Tolerant Architecture for On-board Dual-Core Synthetic...

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15th International Symposium on Applied Reconfigurable Computing

作者： Cruz, Helena Duarte, Rui Policarpo Neto, Horacio INESC ID Rua Alves Redol 9 Lisbon Portugal Univ Lisbon Inst Super Tecn Lisbon Portugal

ISBN: (纸本)9783030172268;9783030172275

In this research work, an on-board dual-core embedded architecture was developed for SAR imaging systems, implementing a reduced-precision redundancy fault-tolerance mechanism. This architecture protects the execution of the backprojection algorithm, capable of generating acceptable SAR images in embedded systems subjected to errors from the space environment. The proposed solution was implemented on a Xilinx SoC device with a dual-core processor. The present work was able to produced images with less 0.65 dB on average, than the fault-free image, at the expense of a time overhead up to 33%, when in the presence of error rates similar to the ones measured in space environment. Notwithstanding, the backprojection algorithm executed up to 1.58 times faster than its single-core version without any fault-tolerance mechanisms.

关键词： Synthetic-Aperture Radar backprojection algorithm Approximate computing FPGA Dual-core SoC

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Interpolation-free method for near-field cross MIMO array imaging

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ELECTRONICS LETTERS 2018年第14期54卷 890-891页

作者： Zhu, Rongqiang Zhou, Jianxiong Cheng, Binbin Fu, Qiang Jiang, Ge Natl Univ Def Technol ATR Lab Changsha 410073 Hunan Peoples R China China Acad Engn Phys Microsyst & Terahertz Res Ctr Chengdu 610200 Sichuan Peoples R China China Acad Engn Phys Inst Elect Engn Mianyang 621900 Peoples R China

In this Letter, an interpolation-free imaging algorithm for a near-field cross MIMO array is presented. This method transforms the measurement data into the wavenumber domain along the receiving direction or the transmitting direction for compensation. Then the imaging result is obtained by 1D inverse Fourier transform and 2D accumulation. This method has the same computational complexity as the backprojection algorithm (BPA) with better imaging quality since interpolation is avoided. The imaging performance of the proposed method, the BPA and the approximate range migration algorithm are compared by experiment.

关键词： medical image processing synthetic aperture radar radar imaging computational complexity interpolation Fourier transforms image reconstruction interpolation-free method near-field cross MIMO array imaging interpolation-free imaging algorithm measurement data wavenumber domain receiving direction transmitting direction imaging result 1D inverse Fourier backprojection algorithm imaging quality imaging performance approximate range migration algorithm

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Study of the ATI SAR Target Signature for Non-Linear Airborne Tracks 1

Study of the ATI SAR Target Signature for Non-Linear Airborn...

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1st IEEE Ukraine Conference on Electrical and Computer Engineering (UKRCON)

作者： Balaban, M. Kovorotniy, A. Gorobets, V. Kivva, F. Goncharenko, Yu. Farquharson, G. Jessup, A. NASU O Ya Usikov Inst Radiophys & Elect Kharkov Ukraine Univ Washington Appl Phys Lab Seattle WA 98105 USA

ISBN: (纸本)9781509030064

The paper shows the results of simulation and analysis of the ATI SAR signatures of the stationary and moving targets for linear and non-linear airborne tracks. Estimated azimuthal displacement of the moving target is found for some simulated and experimental RAW data. It is proposed to use a backprojection algorithm with the estimated squint angle as the digital filter for the filtering of a stationary and slow-moving targets.

关键词： LFM-CW radar synthetic aperture radar alongtrack interferometer raw data symulation backprojection algorithm

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An INS Data-based Micronavigation Method for the Imaging of Multiple Receiver Synthetic Aperture Sonar 10

An INS Data-based Micronavigation Method for the Imaging of ...

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10th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics (CISP-BMEI)

作者： Xu, Kui Tian, Zhen Tang, Jinsong Wang, Jinbo Zhang, Sen Naval Univ Engn Naval Inst Underwater Acoust Technol Wuhan Hubei Peoples R China

ISBN: (纸本)9781538619377

Motion compensation, referred to as micronavigation, is an unavoidable issue to obtain a high quality image for multiple receiver synthetic aperture sonar (SAS). A feasible micronavigation method based on the inertial navigation system (INS) data is presented in this paper. The INS data is obtained from some high-precision inertial navigation equipment, thus the accuracy of motion errors can be guaranteed. Using the back projection algorithm, some imaging results of experiment data are shown in the end of paper. Meanwhile, some imaging results focused by the conventional chirp scaling algorithm are also given, and the compared results show the effectiveness of the presented method.

关键词： imaging technology synthetic aperture sonar multiple receiver micronavigation INS data-based backprojection algorithm

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Coherent Integration with Backprojected Images for Near Field Moving Target

Coherent Integration with Backprojected Images for Near Fiel...

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IEEE Radar Conference (RadarConf)

作者： Huang, Cong Qian, Jiang Wang, Yong Jia, Yong Univ Elect Sci & Technol China Sch Resources & Environm Chengdu 611731 Sichuan Peoples R China Chengdu Univ Technol Coll Informat Sci & Technol Chengdu 611731 Sichuan Peoples R China

ISBN: (纸本)9781509008636

A signal may not be detected and identified due to the presence of serious noise. Coherent integration is an important approach for focusing the energy of the signal in pulse-Doppler radar. For moving targets, the problem of migration through range cells (MTRC) will degrade the coherent integration result. This paper presents a new coherent integration method for multi-channel radar system to focus near field moving targets. The envelope correction coupled with backprojection in spatial and fast-time domain is performed, followed with coherent integration in slow-time domain. The simulated results demonstrate the effectiveness of the method in target detection.

关键词： backprojection algorithm coherent integration multichannel

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