摘要 :
The estimation of two-dimensional motion parameters is the premise of high-precision synthetic aperture radar (SAR) error compensation. In strip mode, it is difficult to directly estimate all phase errors in one range block, so it...
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The estimation of two-dimensional motion parameters is the premise of high-precision synthetic aperture radar (SAR) error compensation. In strip mode, it is difficult to directly estimate all phase errors in one range block, so it isn't accurate to estimate the trajectory using the whole range block. In this paper, a two-dimensional displacement estimation process for multi-rotor multi-rotor unmanned aerial vehicle (UAV) SAR is proposed. It divides the whole aperture into several subapertures, then select several range blocks in each subaperture and calculates their phase error gradients, next restores the two-dimensional displacement one subaperture by one subaperture. Considering that the velocity error will cause envelope error, it uses multiple iterations to decrease the influence of velocity error. Finally, the feasibility is verified by simulation.
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To reduce difficulty of obtaining jamming parameters, combining scattered wave deception jamming method structure with genetic algorithm, a scattered wave deceptive jamming method based on genetic algorithm is proposed against thr...
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To reduce difficulty of obtaining jamming parameters, combining scattered wave deception jamming method structure with genetic algorithm, a scattered wave deceptive jamming method based on genetic algorithm is proposed against three Channel SAR GMTI. Four-dimensional jamming parameter searching problem is separated as a one-dimensional optimization problem and a two-dimensional optimization problem, which will reduce computational burden and jamming parameter acquirement time and raise fidelity of deceptive jamming. In addition, the problem, that tolerance of Doppler rate mismatch is difficult to describe, is solved by transforming an objective function of the two-dimensional optimization problem. By utilizing jamming quality parameters, simulation experiments are provided to verify the effectiveness of SGA method against the three-channel SAR GMTI.
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Change detection method in polarimetric SAR images considers polarization information and features. In order to make better use of polarization information and features for change detection, this paper compared and analyzed differ...
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Change detection method in polarimetric SAR images considers polarization information and features. In order to make better use of polarization information and features for change detection, this paper compared and analyzed different change detection methods in polarimetric SAR image based on probability statistical method. Firstly, based on RADARSAT-2 polarimetric SAR data, four change detection methods were used to generate four change degree maps. Then, through four probability statistical model, we built the fitting models for the four kinds of change degree maps, and obtained 16 kinds of change detection results. The results showed that the 16 combination of change detection methods made full use of more ground information which contains in different polarization modes. Compared with other distribution fitting, the lognormal fitting distribution function can better fit the four change degree maps, and the change detection results are better. The overall accuracy (OA) can be improved by more than 1.53%, and the kappa coefficient can be improved by no less than 0.026. In addition, compared with 16 combined change detection methods, the Wishart-lognormal distribution change detection results are the best. The overall accuracy is 87.76% and kappa coefficient is 0.7469, which realizes the high-precision change detection of the study areas.
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In recent years, there has been an increasing interest in rip currents as an emerging public health issue for researchers. This study aims to detect and identify breaking waves region and surf zone from Sentinel-1 images, and extr...
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In recent years, there has been an increasing interest in rip currents as an emerging public health issue for researchers. This study aims to detect and identify breaking waves region and surf zone from Sentinel-1 images, and extract the rip currents on the Portuguese coast beach. From Sentienl-1 GRD data of two scenes, it shows bright features and dark features as a “jig-saw tooth” appearance, respectively. In this paper, polarization difference of VV-polarization and VH-polarization supports to enhance the contrast between rip currents and background, and the edge detection operator is applied to identify wave breaking area and surf area shown promising result. The area, extension length and flow direction of rip currents are extracted from the image well.
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the terahertz (THz) radar signal distorted by atmospheric propagation should be calibrated to suppress paired echoes in radar images. In this paper, to compensate THz radar signals for atmospheric effects, a procedure is proposed ...
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the terahertz (THz) radar signal distorted by atmospheric propagation should be calibrated to suppress paired echoes in radar images. In this paper, to compensate THz radar signals for atmospheric effects, a procedure is proposed to estimate atmospheric condition based on range profile matching. The scattering centers in the range profile are identified via local maximum clustering to extract the distorted separable scattering centers. An atmospheric lookup table is generated to characterize typical atmospheric condition. The range profile of an arbitrary separable scattering center is simulated under different atmospheric condition to match with the extracted scattering center. The atmospheric condition achieving the highest correlation coefficient is used to compensate for atmospheric effects. To validate the proposed procedure, the THz radar echo composed of several scattering centers is simulated under random atmospheric condition, regarding as the distorted signal for calibration. The estimated atmospheric condition is slightly different from the set values, while the range profile distortion caused by paired echoes is noticeably suppressed using the proposed procedure.
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Multistatic synthetic aperture radar (MuSAR) has the potential for obtaining a high-resolution radar image by coherently collecting echo data of multiple stations. However, the point spread function (PSF) of coherent MuSAR may pre...
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Multistatic synthetic aperture radar (MuSAR) has the potential for obtaining a high-resolution radar image by coherently collecting echo data of multiple stations. However, the point spread function (PSF) of coherent MuSAR may present split mainlobes and high sidelobes because its topology structure of multiple stations is distributed. In this paper, a target reconstruction method based on complex-Radon transform (CRT) is proposed to focus the PSF of coherent MuSAR. First, the echo model of coherent MuSAR is introduced. The wavenumber spectrum distributions of MuSAR based on different topology structures are analyzed. Then, the CRT method is adopted to avoid the coupling of two-dimensional wavenumber spectrum. Following, based on the projected wavenumber spectrum slices, a generalized nonuniform sampling iterative adaptive approach (GIAA) is proposed to reconstruct the targets along different directions. Finally, the high resolution imaging result in the ground plane is obtained based on coordinate transform. Simulations are carried out to verify the proposed method.
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Multistatic forward-looking synthetic aperture radar (MF -SAR) can obtain high-resolution radar imagery of the area in front of the receivers. However, it is difficult to fuse the multiple measurements when the echo data are sampl...
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Multistatic forward-looking synthetic aperture radar (MF -SAR) can obtain high-resolution radar imagery of the area in front of the receivers. However, it is difficult to fuse the multiple measurements when the echo data are sampled with gaps. The quality of reconstructed imagery of the MF -SAR depends on the strict topology and the data fusion methods. To improve the imaging quality with a flexible topology, a coherent fusion method for MF -SAR using the generalized matrix pencil algorithm (GMPA) is proposed. First, the MF-SAR system consists of one stationary transmitter and two receivers is established. The reasons for limiting the topology structure of MF -SAR are analyzed. Second, the generalized bandwidth synthesis direction of the wavenumber spectrum is defined to effectively extrapolate the gap data. The projected measurements are corrected to align the wavenumber spectrum data. Finally, the matrix pencil algorithm is adopted to composite the spatial bandwidth observed by the leading receiver and the following receiver along the generalized bandwidth synthesis direction. Numerical simulations and experimental data are carried out to verify the effectiveness of the proposed method.
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In order to track the near space hypersonic vehicle (NSHV), we propose a tracking model containing aerodynamic and kinematic information using interacting multiple model (IMM) algorithm with accruate speed prior information. Becau...
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In order to track the near space hypersonic vehicle (NSHV), we propose a tracking model containing aerodynamic and kinematic information using interacting multiple model (IMM) algorithm with accruate speed prior information. Because traditional maneuver models are difficult to describe the complex movement characteristics, which involves large-scale high-speed mobile, large flight cover, etc., fault-acceleration model with surface damage model and external disturbance model are proposed. With the model, the state equations are constructed and the system dynamic error is deduced taking variable structure multiple model (VSMM) algorithm as the flitering algorithm. Moreover, an adaptive method for the change of control variables is proposed for setting parameters apporiately in the situations when a prior information is unknown. Simulation experiments are conducted to validate the superiorities among all tracking algorithms in this paper.
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摘要 :
In the radar data association problem, amplitude and state information of target returns are widely used in tracking algorithms, and typically many methods combine them. However, except from uniting them, constructing the correlat...
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In the radar data association problem, amplitude and state information of target returns are widely used in tracking algorithms, and typically many methods combine them. However, except from uniting them, constructing the correlation model among different instants returns is rarely considered. It is known that there is numerous information in radar target returns, but it is complicated to make comprehensive consideration. In this paper, we not only approximate the joint distribution of squared amplitudes based on the Copula function but unite the state information of target returns. Regarding squared amplitudes as statistics to derive the conditional probability density function (PDF), combine with state information to predict the scope of latter instant statistics, which can be used to improve certain anti-interference performance in the target-detection-during-tracking problem. Furthermore, this algorithm will consider about kinematic state and give the most reasonable measurement the highest possibility among the numerous ones radar receiving. And numerical results will be utilized to verify the effectiveness of the proposed method.
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