scholarly journals Azimuth Multichannel Reconstruction for Moving Targets in Geosynchronous Spaceborne–Airborne Bistatic SAR

2020 ◽  
Vol 12 (11) ◽  
pp. 1703
Author(s):  
Wei Xu ◽  
Zhengbin Wei ◽  
Pingping Huang ◽  
Weixian Tan ◽  
Bo Liu ◽  
...  
Keyword(s):  
Velocity Estimation ◽  
Target Velocity ◽  
Moving Target ◽  
Reconstruction Method ◽  
Moving Targets ◽  
Raw Data ◽  
Stationary Target ◽  
Slant Range ◽  
Geometry Model ◽  
Imaging Results

In a multichannel geosynchronous spaceborne–airborne bistatic synthetic aperture radar (GEO-SA-BiSAR) system, the airborne receiver can obtain high-resolution microwave images with good signal-to-noise ratios (SNRs) by passively receiving echoes from the desired area. Since the Doppler modulation and range history of a moving target are obviously different from a stationary target, a signal geometry model for moving targets in multichannel GEO-SA-BiSAR is established in this paper. According to simulation results, the along track velocity introduces target defocusing in azimuth, and the slant range velocity mainly causes multiple false targets. To resolve these problems, a modified multichannel reconstruction method in azimuth channel GEO-SA-BiSAR is proposed according to the azimuth multichannel impulse response of the imaged moving target. Before azimuth multichannel raw data combination, both spatial-variant range cell migration correction (RCMC) and azimuth nonlinear chirp scaling (ANLCS) should be performed to reduce the influence of the range offset and lower the Doppler bandwidth of the whole raw data, respectively. Afterward, a novel azimuth multichannel reconstruction algorithm is carried out via the modified reconstruction matrix based on the estimated target velocity. The target slant range velocity estimation is implemented by introducing the signal intensity ratio (SIR). Compared with the conventional method for the stationary target to handle the raw data of the moving target, the false targets could be obviously suppressed by using the proposed approach. Imaging results on both simulated point and distributed scene targets validate the proposed multichannel reconstruction approach.

scholarly journals A Method of Marine Moving Targets Detection in Multi-Channel ScanSAR System

2020 ◽  
Vol 12 (22) ◽  
pp. 3792
Author(s):  
Junying Yang ◽  
Xiaolan Qiu ◽  
Mingyang Shang ◽  
Lihua Zhong ◽  
Chibiao Ding
Keyword(s):  
Spatial Distribution ◽  
Reference Value ◽  
Sparse Recovery ◽  
Velocity Estimation ◽  
High Signal ◽  
Moving Target ◽  
Moving Targets ◽  
Position Information ◽  
Wide Area Monitoring ◽  
Area Monitoring

Azimuth multi-channel Synthetic Aperture Radar (SAR) system operated in burst mode makes high-resolution ultrawide-swath (HRUS) imaging become a reality. This kind of imaging mode has excellent application value for the maritime scenarios requiring wide-area monitoring. This paper suggests a moving target detection (MTD) method of marine scenes based on sparse recovery, which integrates detection, velocity estimation, and relocation. Firstly, the typical phenomenon of scene folding in the coarse-focused domain is introduced in detail. Given that the spatial distribution of moving vessels is highly sparse, the idea of sparse recovery is utilized to acquire the azimuth time characterizing the position of the moving target reasonably. Subsequently, the radial velocity and position information about the targets are obtained simultaneously. What makes the proposed method effective are two characteristics of the moving targets in ocean scenes, high signal-to-clutter ratio (SCR) and sparsity of the spatial distribution. Then, estimation performances under different SCR are analyzed by Monte Carlo experiments. And the actual SCR of the vessels in the ocean scene obtained by GaoFen-3 dual-receive channel mode is invoked as a reference value to verify the effectiveness. Besides, some simulation experiments demonstrate the capability to indicate marine moving targets.

APPROACH OF MULTIPLE MOVING TARGETS DETECTION FOR MICROWAVE SURVEILLANCE SENSORS

2007 ◽  
Vol 04 (01) ◽  
pp. 57-68 ◽  
Author(s):  
WENQIN WANG
Keyword(s):  
Information Acquisition ◽  
Fractional Fourier Transform ◽  
Target Velocity ◽  
Fourier Domain ◽  
Moving Target ◽  
Moving Targets ◽  
True Position ◽  
Simulation Results ◽  
Multiple Moving Targets ◽  
Magnitude Improvement

Multiple moving targets detection is one of the fundamental problems in information acquisition. In this paper, the use of a transformable period and symmetrical linear frequency modulated (TPS-LFM) waveform for microwave surveillance sensor multiple moving targets identification, is proposed. In order to accurately estimate target's true position and velocity, a relatively unknown yet powerful technique, the so-called fractional Fourier transform (FrFT), is applied to estimate the moving target parameters. By mapping a target's signal onto a fractional Fourier axis, the FrFT permits a constant-velocity target to be focused in the fractional Fourier domain thereby affording orders of magnitude improvement in signal-clutter-ratio. Moving target velocity and position parameters are derived and expressed in terms of an optimum fractional angle and a measured fractional Fourier position, allowing a target to be accurately located. Moreover, to resolve the problem whereby weak targets are covered by the sidelobes of strong ones, the CLEAN technique is also applied. Simulation results show that the method is effective in estimating target velocity and position parameters for microwave surveillance sensors.

scholarly journals A Moving Target Velocity Estimation Method Based on the MC-MASA SAR Mode

2021 ◽  
Vol 13 (9) ◽  
pp. 1632
Author(s):  
Yamin Wang ◽  
Jie Chen ◽  
Wei Liu ◽  
Chunsheng Li ◽  
Wei Yang
Keyword(s):  
Estimation Method ◽  
Velocity Estimation ◽  
Estimation Accuracy ◽  
Target Range ◽  
Target Velocity ◽  
Moving Target ◽  
Sar Images ◽  
Background Clutter ◽  
Along Track ◽  
Displacement Phase

Imaging position shift based on the multiple azimuth squint angles (MASA) mode is effective for target azimuth velocity estimation, whereas accuracy is low when target range velocity is high. In this paper, the estimation problem for both target azimuth and range velocities is considered based on the multi-channels MASA (MC-MASA) mode. Firstly, the acquisition geometry of MC-MASA mode and Doppler characteristics of a moving target are analyzed in detail, especially in squint mode. Then, for better moving target estimation, the stationary background clutter is removed using the displacement phase center antenna (DPCA) technique, and the failure in range velocity estimation with sequential SAR images is also discussed. Furthermore, a modified along-track interferometry (ATI) is proposed to preliminarily reconstruct the azimuth-and-range velocity map based on the MC-MASA mode. Since the velocity estimation accuracy is dependent on squint angle and signal-to-clutter ratio (SCR), the circumstances are divided into three cases with different iteration estimation strategies, which could expand the scene application scope of velocity estimation and achieve a high estimation accuracy along both azimuth and range directions. Finally, the performance of the proposed method is demonstrated by experimental results.

scholarly journals Simulation of Moving Target Indication Radar System Based on VisSim/Comm Application

2021 ◽  
Vol 5 (2) ◽  
pp. 38-45
Author(s):  
Ghassan A. QasMarrogy ◽  
Husham J. Ahmad
Keyword(s):  
Mechanical Properties ◽  
Delay Line ◽  
Radar System ◽  
Moving Target ◽  
Moving Targets ◽  
Simulation Design ◽  
Stationary Target ◽  
Know How ◽  
Radar Signals

Moving target indication (MTI) is mainly designed to detect moving targets and while unmoving targets are filtered out. It focuses on the technique of the modern stationary target indication (STI), by using directly the signal details to determine the reflecting object’s mechanical properties, after that it becomes easier to find moving or non-moving targets. This paper presents the simulation design of the MTI radar system. The main purpose of this design is to help students in understanding the radar system subject and help teachers to explain this subject in a simpler approach. Both students and teachers need to know how the signals inside the MTI radar processor are working and how they are generated and related to each other. This paper introduces a method of simulation of MTI radar signals including, A-scope radar display, transmitted and returned radar pulses with constant and multiple PRF, n-delay line cancellers.

Ocular Tracking of Moving Targets: Effects of Perturbing the Background

2004 ◽  
Vol 91 (6) ◽  
pp. 2474-2483 ◽  
Author(s):  
Yasushi Kodaka ◽  
Kenichiro Miura ◽  
Kazuyo Suehiro ◽  
Aya Takemura ◽  
Kenji Kawano
Keyword(s):  
Opposite Direction ◽  
Direction Selectivity ◽  
Moving Target ◽  
Moving Targets ◽  
Progressive Reduction ◽  
Stationary Target ◽  
Ocular Tracking ◽  
Per Se ◽  
Background Motion ◽  
Stationary Background

Primates are able to track a moving target with their eyes, even when the target is seen against a stationary textured background. In this situation, the tracking eye movement induces motion of the background images on the retina (reafference) that competes with the motion of the target's retinal image, potentially disrupting the tracking of the target. Previous work on humans reported that brief perturbations of the background in the opposite direction to pursuit were much less disruptive than perturbations in the same direction as pursuit. Furthermore, if the background moved together with the pursuit target—so as to effectively eliminate the reafference—then the effects of a subsequent background perturbation showed less dependence on direction. This suggested that the direction selectivity to background perturbations during pursuit against a stationary background was due, at least in part, to the prior motion of the background secondary to the pursuit. We now report similar findings in monkeys, and in addition, have investigated the effect of moving the background while the animal was fixating a stationary target. In this situation, the ocular tracking responses to subsequent brief perturbations of the moving background were weaker when the perturbations were in the same direction as the prior background motion than when in the opposite direction. This suggests that the selective insensitivity to the reafferent visual input associated with pursuit across a stationary background is, at least in part, independent of pursuit per se and attributable to a progressive reduction in the sensitivity to sustained background motion.

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