scholarly journals A 3-D SAR Imaging Method Based on Back Projection Algorithm

2021 ◽  
Vol 2083 (3) ◽  
pp. 032050
Author(s):  
Qian Han ◽  
Pengbo Wang ◽  
Xinkai Zhou ◽  
Xinchang Hu ◽  
Yanan Guo
Keyword(s):  
3D Imaging ◽  
Bp Algorithm ◽  
Projection Algorithm ◽  
Imaging Method ◽  
Back Projection ◽  
Imaging Processing ◽  
Imaging Algorithm ◽  
Imaging Results ◽  
2D Imaging ◽  
Low Efficiency

Abstract 3D back projection (BP) algorithm is an imaging algorithm based on time domain echo data, which effectively solves the overlapping mask problem existing in 2D SAR. It can complete the imaging processing of echo signal under any geometry configuration, and has the advantages of high target focusing accuracy and high phase preservation. However, the high complexity and low efficiency of 3D BP imaging algorithm limit its application and development. In this paper, a 3d imaging method based on improved back projection algorithm is proposed. Aiming at the problem that existing imaging algorithms need 2D imaging first and then 3D imaging, an improved 3D BP algorithm is proposed to directly 3D imaging, which avoids 2d imaging processing. The proposed method simplifies the steps of the traditional 3D BP algorithm and improves the efficiency of the algorithm. The validity and effectiveness of the proposed method are verified by the 3d imaging results of simulated lattice targets.

scholarly journals Three-Dimensional Imaging of Terahertz Circular SAR with Sparse Linear Array

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2477 ◽  
Author(s):  
Jubo Hao ◽  
Jin Li ◽  
Yiming Pi
Keyword(s):  
3D Imaging ◽  
Linear Array ◽  
Ground Plane ◽  
Three Dimensional ◽  
Terahertz Waves ◽  
Recovery Method ◽  
Imaging Algorithm ◽  
Imaging Geometry ◽  
Imaging Results ◽  
Sparse Linear Array

Due to the non-contact detection ability of radar and the harmlessness of terahertz waves to the human body, three-dimensional (3D) imaging using terahertz synthetic aperture radar (SAR) is an efficient method of security detection in public areas. To achieve high-resolution and all aspect imaging, circular trajectory movement of radar and linear sensor array along the height direction were used in this study. However, the short wavelength of terahertz waves makes it practically impossible for the hardware to satisfy the half-wavelength spacing condition to avoid grating lobes. To solve this problem, a sparse linear array model based on the equivalent phase center principle was established. With the designed imaging geometry and corresponding echo signal model, a 3D imaging algorithm was derived. Firstly, the phase-preserving algorithm was adopted to obtain the 2D image of the ground plane for each sensor. Secondly, the sparse recovery method was applied to accomplish the scattering coefficient reconstruction along the height direction. After reconstruction of all the range-azimuth cells was accomplished, the final 3D image was obtained. Numerical simulations and experiments using terahertz radar were performed. The imaging results verify the effectiveness of the 3D imaging algorithm for the proposed model and validate the feasibility of terahertz radar applied in security detection.

scholarly journals Precision Imaging of Frequency Stepped SAR with Frequency Domain Extracted HRRP and Fast Factorized Back Projection Algorithm

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Can-bin Yin ◽  
Da Ran
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Single Point ◽  
Projection Algorithm ◽  
Great Promise ◽  
Back Projection ◽  
Imaging Processing ◽  
Block Partition ◽  
Range Resolution ◽  
High Range

Novel frequency domain extracted method (FDEM) to obtain high range resolution profile (HRRP) for frequency stepped synthetic aperture radar (SAR) is proposed in this paper, and the mathematical principle and formulas of this new HRRP obtaining idea combined with classical fast Fourier transform (FFT), chirp z transform (CZT), and single point Fourier transform (SPFT) are deduced, analyzed, and compared in detail. Based on the HRRP data, precision imaging processing is completed using a data block partition based fast factorized back projection algorithm. Imaging validations are executed and all results proved that the FDEM has a great capability of antijamming. It is more effective than conventional time domain IFFT method (TDM) and shows a great promise in frequency stepped radar imaging and applications.

scholarly journals Analysis of the Azimuth Ambiguity and Imaging Area Restriction for Circular SAR Based on the Back-Projection Algorithm

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4920 ◽  
Author(s):  
Bang Du ◽  
Xiaolan Qiu ◽  
Lijia Huang ◽  
Songlin Lei ◽  
Bin Lei ◽  
...  
Keyword(s):  
Beam Width ◽  
Bp Algorithm ◽  
Projection Algorithm ◽  
Parameter Design ◽  
Observation Angle ◽  
Back Projection ◽  
Theoretical Support ◽  
Relationship Of ◽  
The Relationship ◽  
Small Observation

Circular synthetic aperture radar (CSAR) has a 360° observation capability on the central observation scenario. A typical way to process CSAR imaging is to cut data into small sub-apertures because most targets are only coherent at a very small observation angle. There are many sub-aperture imaging methods after development in recent years. The back-projection algorithm is widely used because it is simple and can be applied to an arbitrary trajectory. Because of the limitation of the Nyquist sampling frequency and influence of the antenna sidelobe, azimuth ambiguity is a phenomenon that may occur in the radar imaging process. The existing researches typically choose the back-projection (BP) imaging area according to the SAR platform flight path and the antenna beam width. The limitation of the CSAR imaging area and its azimuth ambiguity region are rarely analyzed theoretically. This paper focus on the sub-aperture imaging of CSAR, based on the BP algorithm, which derives the relationship of azimuth ambiguity with CSAR parameters such as the pause repeat frequency (PRF), slant range angle, velocity of radar platform, etc. This paper proposes an equation for the calculation of the azimuth ambiguity region and analyzes the limitations, which provides theoretical support for CSAR parameter design, imaging area selection, and azimuth ambiguity analysis.

A Windowed Range Migration Imaging Algorithm for Ground Penetrating Radar Applications

2013 ◽  
Vol 477-478 ◽  
pp. 1504-1508
Author(s):  
Wen Tai Lei ◽  
Yu Jia Shi
Keyword(s):  
Ground Penetrating Radar ◽  
Imaging Method ◽  
Imaging Algorithm ◽  
Migration Imaging ◽  
Imaging Results ◽  
Radar Applications ◽  
Range Migration ◽  
Ground Penetrating ◽  
Quality Imaging

The article proposes a new imaging method for ground penetrating radar (GPR) nondestructive testing (DET). Traditional GPR range migration (RM) imaging algorithm regards all the data in GPR echo data as equally important. This assumption is always not in consistent with real GPR detection scenario and usually cannot obtain high quality imaging results. To improve the quality of GPR imaging results, a new windowed RM imaging algorithm is presented in this paper. The radar profile is processed by one-dimensional windowed Fourier transform. The central point of window function is determined by maximum intensity technique. By using windowed RM imaging algorithm, the clutter of GPR profile is suppressed and the imaging results quality is improved. The simulation of this algorithm is processed and experimental results validate the feasibility of this algorithm.

An Improved Iteration Back Projection Imaging Technique for Surface Penetrating Radar Applications

2013 ◽  
Vol 477-478 ◽  
pp. 1509-1513 ◽  
Author(s):  
Wen Tai Lei ◽  
Yu Jia Shi
Keyword(s):  
Imaging Technique ◽  
Local Maximum ◽  
Subsurface Imaging ◽  
Back Projection ◽  
Imaging Algorithm ◽  
Multi Scale ◽  
Imaging Results ◽  
Maximum Extraction ◽  
Resolution Imaging ◽  
Radar Applications

Traditional back projection(BP) imaging algorithm can be used to obtain 2-dimensional subsurface imaging results of testing materials and thus provide useful information for material nondestructive testing(NDT). But it’s restricted by heavy computation burden and cannot be widely used in surface penetrating radar(SPR) NDT area. To meet the needs of high resolution imaging and low computation burden, an improved iteration back projection imaging algorithm is presented. With the multi scale iteration processing and local maximum extraction method, it can get appropriate resolution imaging results with much lower computation. The simulation of this algorithm is processed and experimental results validate the feasibility of this algorithm.

scholarly journals A Novel Inverse Synthetic Aperture Rada Imaging Method for Maneuvering Targets Based on Modified Chirp Fourier Transform

2018 ◽  
Vol 8 (12) ◽  
pp. 2443 ◽  
Author(s):  
Yakun Lv ◽  
Yongping Wang ◽  
Yanhong Wu ◽  
Hongyan Wang ◽  
Lei Qiu ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Descent Method ◽  
Synthetic Aperture ◽  
Imaging Method ◽  
Gradient Descent Method ◽  
Minimum Entropy ◽  
Echo Signal ◽  
Maneuvering Targets ◽  
Imaging Results ◽  
Low Efficiency

When inverse synthetic aperture radar (ISAR) imaging maneuvers targets, the azimuth echo of the target scattering point causes a Doppler frequency time-varying problem, which leads to the blurring and defocusing of the imaging results. Traditional imaging methods struggle to meet the imaging requirements for maneuvering targets due to a poor imaging effect or low efficiency. Given these challenges, a modified chirp Fourier transform (MCFT) imaging method is proposed in this paper, based on the specific relationship between the target rotation parameters and the radar echo signal parameters. Firstly, discrete chirp Fourier transform is used to quickly estimate the target’s coarse rotation ratio. Then, the minimum entropy function and gradient descent method are used to calculate the target’s accurate rotation ratio. Finally, the azimuth focusing image is accomplished by performing MCFT once on the azimuth echo signal using the accurate rotation ratio. This method avoids estimating and separating the sub-echo components one-by-one, considerably improves the imaging speed, and guarantees the best imaging quality by applying the global minimum entropy principle. The experimental results show that the proposed method effectively achieves the two-dimensional, high-quality, and fast imaging of maneuvering targets.

scholarly journals A Novel Ship Imaging Method with Multiple Sinusoidal Functions to Match Rotation Effects in Geosynchronous SAR

2020 ◽  
Vol 12 (14) ◽  
pp. 2249
Author(s):  
Wei Xiong ◽  
Ying Zhang ◽  
Xichao Dong ◽  
Chang Cui ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Rotational Motion ◽  
Numerical Experiments ◽  
Projection Algorithm ◽  
Synthetic Aperture ◽  
Imaging Method ◽  
Back Projection ◽  
Rotation Effect ◽  
Signal Model ◽  
Range Migration ◽  
Sinusoidal Functions

Geosynchronous Synthetic Aperture Radar (GEO SAR) has a very long Coherent Processing Interval (in the order of hundreds of seconds) compared with other SAR platforms. Thus, the current methods of rotation effect matching and ship imaging that operate within a relatively short Coherent Processing Interval (in the order of seconds) are obviously not applicable. To address this problem, a novel ship imaging method with multiple sinusoidal functions matching for rotation effects is proposed for GEO SAR. Firstly, the influence of the rotational motion of a ship on the slant range is analyzed. It can be matched with the sum of multiple sinusoidal functions, and the signal model of a ship with rotational motion is given. Then, multiple sinusoidal functions for the matching-based ship imaging method are proposed, and their procedures are presented as follows: (1) The Generalized Keystone Transform and Generalized Dechirp Process (GKTGDP) is modified to compensate for the range migration and phase caused by the motion of GEO SAR. Then, the signal is focused at the frequencies of sinusoidal functions, and the frequencies can be matched. (2) From the matched frequencies, the other parameters of sinusoidal functions can be matched by parameter searching. (3) Based on the matched results, the Back Projection Algorithm (BPA) is used to take an image of the ship with rotational motion. Finally, the effectiveness of the proposed method is verified by numerical experiments.

scholarly journals FDBP-InSAR: An Efficient Algorithm for InSAR Imaging via Frequency Domain Back Projection

2020 ◽  
Vol 12 (21) ◽  
pp. 3527
Author(s):  
Shunjun Wei ◽  
Yue Wu ◽  
Jiadian Liang ◽  
Shan Liu ◽  
Mou Wang ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Projection Algorithm ◽  
Imaging Method ◽  
Back Projection ◽  
High Quality ◽  
Phase Compensation ◽  
Coherent Integration ◽  
Uniform Grids ◽  
Point To Point ◽  
The Time Domain

High-quality focusing with accurate phase-preserving is a significant and challenging step in interferometric synthetic aperture radar (InSAR) imaging. Compared with conventional frequency-based imaging algorithms, the time-domain back-projection algorithm (TDBPA) can greatly ensure the accuracy of imaging and phase-preserving by point-to-point coherent integration but suffers from huge computational complexity. In this paper, we propose an efficient InSAR imaging method, called a frequency-domain back-projection algorithm (FDBPA), to achieve high-resolution focusing and accurate phase-preserving of InSAR imaging. More specifically, FDBPA is utilized to replace the traditional point-to-point coherent integration of TDBPA with frequency-domain transform. It divides the echo spectrum into uniform grids and transforms the range compression data into the range frequency domain. Phase compensation and non-uniform Fourier transform of the underlying scene are implemented to achieve image focusing in the wavenumber domain. Then, the interferometric phase of the target scene can be preserved by accurate phase compensation of the target’s distance. FDBPA avoids the repetitive calculation of index values and point-to-point coherent integration which reduces the time complexity compared with TDBPA. The characteristics of focusing and phase-preserving of our method are analyzed via simulations and experiments. The results demonstrate the efficiency and high-quality imaging of the FDBPA method. It can improve the imaging efficiency by more than three times, while keeping similar imaging accuracy compared with TDBPA.

X-Ray Tomography for Electronic Packages

2000 ◽  
Author(s):  
Deepak Goyal
Keyword(s):  
3D Imaging ◽  
Development Time ◽  
Analytical Techniques ◽  
Electronic Packages ◽  
X Ray ◽  
Imaging Capability ◽  
Imaging Results ◽  
Key Drivers ◽  
Analytical Tools ◽  
Non Destructive

Abstract Next generation assembly/package development challenges are primarily increased interconnect complexity and density with ever shorter development time. The results of this trend present some distinct challenges for the analytical tools/techniques to support this technical roadmap. The key challenge in the analytical tools/techniques is the development of non-destructive imaging for improved time to information. This paper will present the key drivers for the non-destructive imaging, results of literature search and evaluation of key analytical techniques currently available. Based on these studies requirements of a 3D imaging capability will be discussed. Critical breakthroughs required for development of such a capability are also summarized.

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