scholarly journals A Bistatic Imaging Method for GEOSAR in the Strip Mode and UAVSAR in the Steering Beam Mode

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
W. Zhuo-qun ◽  
L. Ya-jun ◽  
S. Sheng ◽  
L. Shuang-shuang ◽  
X. Jin-guo ◽  
...  
Keyword(s):  
Earth Orbit ◽  
Imaging Method ◽  
Static State ◽  
Orbital Inclination ◽  
Imaging Algorithm ◽  
Scaling Transform ◽  
Aerial Vehicle ◽  
Frequency Aliasing ◽  
Progressive Scan ◽  
Beam Mode

The bistatic configuration with a geosynchronous orbital SAR (GEOSAR) transmitter and unmanned aerial vehicle SAR (UAVSAR) receiver can continuously image in any dangerous and interesting district. In this paper, the new imaging method in the case with the smaller orbital inclination of geosynchronous earth orbit and the steering beam working mode of UAVSAR was mainly studied and analyzed. GEOSAR can be approximately expressed as a static state, and only the receiver provides all the Doppler information. UAVSAR works in the steering beam modes, such as spotlight, sliding spotlight, and TOPS (Terrain Observation by Progressive Scan) mode. The azimuth bandwidth increased by the steering beam causes an aliasing situation in the azimuth frequency domain. To solve this problem, the proposed imaging method corrects the azimuth frequency aliasing using the scaling transform and the bulk azimuth compression. Compared with the traditional imaging method, the simulation validates perfectly the effectiveness of the bistatic imaging algorithm.

scholarly journals Link Budget Analysis for Reconfigurable Smart Surfaces in Aerial Platforms

2020 ◽  
Author(s):  
SAFWAN ALFATTANI ◽  
Wael Jaafar ◽  
Yassine Hmamouche ◽  
Halim Yanikomeroglu ◽  
Abbas Yongacoglu
Keyword(s):  
Communication Systems ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Budget Analysis ◽  
Smart Surfaces ◽  
Aerial Vehicle ◽  
Link Budget ◽  
Aerial Platforms ◽  
High Altitude Platform Station ◽  
Aerial Platform

In this paper, we derive the link budget relations for<br>communications assisted by reconfigurable smart surfaces (RSS).<br>Specifically, under specular and scattering paradigms, we provide<br>link budget expressions for an RSS-assisted communication on<br>the ground, where the RSS is either mounted on a building, or on<br>an aerial platform, such as an unmanned aerial vehicle (UAV),<br>a high altitude platform station (HAPS), or a low-earth orbit<br>satellite (LEO). The obtained numerical results provide design<br>guidelines for RSS-assisted communication systems, including the<br>recommended aerial platform to use, the size of RSS for each<br>type of the platforms, and the operating frequencies. <br>

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 MIMO-Based Forward-Looking SAR Imaging Algorithm and Simulation

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ziqiang Meng ◽  
Yachao Li ◽  
Shengqi Zhu ◽  
Yinghui Quan ◽  
Mengdao Xing ◽  
...  
Keyword(s):  
Multiple Input Multiple Output ◽  
Algorithm Design ◽  
Forward Direction ◽  
Mimo Radar ◽  
Imaging Method ◽  
Imaging Algorithm ◽  
Comparison Results ◽  
Input Multiple Output ◽  
Airborne Sar ◽  
Forward Looking

Multiple-input multiple-output (MIMO) radar imaging can provide higher resolution and better sensitivity and thus can be applied to targets detection, recognition, and tracking. Missile-borne forward-looking SAR (MFL-SAR) is a new and special MIMO radar mode. It has advantage of two-dimensional (2D) imaging capability in forward direction over monostatic missile-borne SAR and airborne SAR. However, it is difficult to obtain accurate 2D frequency spectrum of the target echo signal due to the high velocity and descending height of this platform, which brings a lot of obstacles to imaging algorithm design. Therefore, a new imaging algorithm for MFL-SAR configuration based on the method of series reversion is proposed in this paper. This imaging method can implement range compression, secondary range compression (SRC), and range cell migration correction (RCMC) effectively. Finally, some simulations of point targets and comparison results confirm the efficiency of our proposed algorithm.

scholarly journals An Industrial B-Mode Phased Array Ultrasonic Imaging Reconstruction Algorithm Based on FRI Sampling

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Guangzhi Dai ◽  
Zhiyong He ◽  
Song Lin
Keyword(s):  
Phased Array ◽  
Simulation Experiment ◽  
Ultrasonic Imaging ◽  
Reconstruction Algorithm ◽  
Imaging Method ◽  
Sampling Point ◽  
Simple Circuit ◽  
Ultrasonic Signals ◽  
Imaging Algorithm ◽  
Imaging Reconstruction

Firstly, a novel FRI sampling model has been proposed according to the characteristics of ultrasonic signals. The model has the advantages such as good stability, strong antinoise ability, simple circuit implementation, and fewer preconditions, compared to the traditional methods. Then, in order to verify the validity of the sampling model, the method is applied to B-type ultrasonic imaging, and a B-type phased array ultrasonic imaging algorithm based on FRI sampling model is proposed. Finally, the algorithm simulation experiment is designed, and the results show that the sampling point required by the proposed FRI sampling model is only 0.1% of the traditional B-type phased array ultrasonic imaging method, and the sampling frequency of the proposed ultrasonic imaging algorithm is only 0.0077% of the traditional B-type ultrasonic imaging method. Additionally, the experiment result indicates that this algorithm is more applicable to phased array ultrasonic imaging than the SOS filter is.

scholarly journals Research of a Radar Imaging Algorithm Based on High Pulse Repetition Random Frequency Hopping Synthetic Wideband Waveform

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5424 ◽  
Author(s):  
Songhua He ◽  
Xiaotian Wu
Keyword(s):  
Pulse Compression ◽  
Coupling Effect ◽  
Frequency Hopping ◽  
Pulse Repetition ◽  
Imaging Method ◽  
Image Processing Algorithm ◽  
Compression Process ◽  
Imaging Algorithm ◽  
Random Frequency ◽  
High Pulse

Aiming at the imaging algorithm of high-pulse-repetition random-frequency-hopping synthetic wideband radar on a supersonic/hypersonic aircraft platform, this study established an echo simulation model of target and clutter, analyzed the special range-Doppler coupling effect and its influence on imaging, and proposes a method of imaging with pipeline-parallel processing based on generalized 2D matched-filtering and Doppler pre-processing. In the method, Doppler-beam-sharpening was advanced to be performed with the pulse compression process in each frame, and the special range-Doppler coupling effect caused by high dynamic motion of platform and random frequency hopping in bandwidth synthesis was well suppressed; several modes of random frequency hopping were designed and the pipeline-parallel image processing algorithm was optimized for each mode. Theoretical analysis and simulation results show that the proposed imaging method can effectively avoid the divergence of 2D range-Doppler images in the range direction, and can meet the requirements of real-time imaging.

DE-ORBIT BEHAVIORS OF NANOSECOND LASER DRIVING SMALL SCALE SPACE DEBRIS IN LOW EARTH ORBIT

2020 ◽  
Vol 51 (1) ◽  
pp. 1-5
Author(s):  
Yingwu Fang
Keyword(s):  
Numerical Simulations ◽  
Space Debris ◽  
Laser Pulses ◽  
Scale Space ◽  
Low Earth Orbit ◽  
Small Scale ◽  
Nanosecond Laser ◽  
Earth Orbit ◽  
Orbital Inclination ◽  
Irradiation Angle

The aim of this article was to address the de-orbit behaviors of space-based laser driving small scale space debris in low earth orbit (LEO) based on different orbit and laser parameters in coplanar/non-coplanar conditions. The de-orbit model of space-based laser irradiating small scale space debris was established, the de-orbit rules of irradiation angle and irradiation distance with action time in different orbital inclination and right ascension of the ascending node (RAAN) were investigated by numerical simulations, and the change rules of the perigee altitude with the number of laser pulses were discussed in different orbital inclination and RAAN. As a result, the clearance window of removing small scale space debris was described in detail. These results of numerical simulations will provide theoretical guide for designing clear schemes and selecting efficient parameters.

scholarly journals An Improved Full-Aperture ScanSAR Imaging Method Integrating the MIAA Based Aperture Interpolation

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Jiaqi Ning ◽  
Dacheng Liu ◽  
Kaiyu Liu ◽  
Heng Zhang ◽  
Yingjie Wang
Keyword(s):  
Missing Data ◽  
Target Detection ◽  
High Precision ◽  
Synthetic Aperture ◽  
Imaging Method ◽  
Imaging Algorithm ◽  
Radar Antenna ◽  
Azimuth Resolution ◽  
Iterative Adaptive Approach ◽  
Wide Swath

In the scanning synthetic aperture radar (ScanSAR) mode, the radar antenna sweeps through different range subswaths to image a wide swath. The full-aperture imaging algorithm for ScanSAR data has been widely used because it can be realized by exploiting the existing standard high-precision Stripmap SAR processor and does not require stitch processing in the azimuth. However, both the focused image and the interferogram achieved by full-aperture processing suffer from spikes. The spikes adversely affect the ScanSAR-related applications, such as target detection and interferometry. To effectively suppress the spikes, an improved algorithm based on the missing-data iterative adaptive approach (MIAA) is proposed in this manuscript. Besides, the proposed method can also improve the azimuth resolution of ScanSAR images. Simulation and experimental results demonstrate that this algorithm has better performance when processing ScanSAR data compared with existing methods.

A New ISAR Imaging Method of Ballistic Midcourse Target

2011 ◽  
Vol 65 ◽  
pp. 485-490
Author(s):  
Teng Lei ◽  
Jin Mang Liu ◽  
Gang Wang ◽  
Song Li
Keyword(s):  
Azimuth Angle ◽  
Imaging Method ◽  
Cross Term ◽  
Imaging Algorithm ◽  
Sparse Decomposition ◽  
Range Resolution ◽  
Range Cell ◽  
Target Imaging ◽  
Isar Imaging ◽  
Micro Motion

A new micro-motion ISAR imaging algorithm based on the MP sparse decomposition is proposed in this paper. The algorithm use the changes of azimuth angle caused by micro-motion to achieve high cross range resolution, and decompose the echoes of the same range cell before Wigner-Ville transformation to eliminate the cross-term interference. Compared with the traditional Range-Doppler algorithm and the Wigner-Ville imaging algorithm, the new algorithm considered here exhibits better imaging precision and is without cross-term interference. The simulated results have demonstrated that it is an effective method for the micro-motion target imaging.

scholarly journals Link Budget Analysis for Reconfigurable Smart Surfaces in Aerial Platforms

2020 ◽  
Author(s):  
SAFWAN ALFATTANI ◽  
Wael Jaafar ◽  
Yassine Hmamouche ◽  
Halim Yanikomeroglu ◽  
Abbas Yongacoglu
Keyword(s):  
Communication Systems ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Budget Analysis ◽  
Smart Surfaces ◽  
Aerial Vehicle ◽  
Link Budget ◽  
Aerial Platforms ◽  
High Altitude Platform Station ◽  
Aerial Platform

In this paper, we derive the link budget relations for<br>communications assisted by reconfigurable smart surfaces (RSS).<br>Specifically, under specular and scattering paradigms, we provide<br>link budget expressions for an RSS-assisted communication on<br>the ground, where the RSS is either mounted on a building, or on<br>an aerial platform, such as an unmanned aerial vehicle (UAV),<br>a high altitude platform station (HAPS), or a low-earth orbit<br>satellite (LEO). The obtained numerical results provide design<br>guidelines for RSS-assisted communication systems, including the<br>recommended aerial platform to use, the size of RSS for each<br>type of the platforms, and the operating frequencies. <br>

Group sparsity based imaging algorithm for TWRI under wall parameter uncertainties

2016 ◽  
Vol 40 (1) ◽  
pp. 251-260 ◽  
Author(s):  
Yanpeng Sun ◽  
Shi Zhang ◽  
Zhao Cui
Keyword(s):  
High Resolution ◽  
Matching Pursuit ◽  
Multipath Propagation ◽  
Reconstruction Algorithm ◽  
Imaging Method ◽  
Group Sparsity ◽  
Parameter Uncertainties ◽  
Reconstruction Procedure ◽  
Imaging Algorithm ◽  
Imaging Algorithms

Through-the-wall radar imaging (TWRI) applications allow accurate target localization and high-resolution imaging. However, multipath propagation generates challenges to the image reconstruction procedure. With distortions in the received radar signals, traditional imaging algorithms are not able to acquire high-resolution images. The unpredictability of the indoor scattering environment makes this even worse. In this paper, a novel block orthogonal matching pursuit (BOMP)-based group-sparsity reconstruction algorithm combined with particle swarm optimization (PSO) is proposed for reliable scene reconstruction. The proposed imaging algorithm can recover the image of targets by exploiting multipath propagation and simultaneously estimating wall parameters with high accuracy. The effectiveness of the proposed imaging method has been further demonstrated via simulation results.

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