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Ray tracing/correlation approach to estimation of surface-based duct parameters from radar clutter

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Chinese Physics B 2010年第4期19卷 484-491页

作者：赵小峰黄思训盛峥 Institute of Meteorology PLA University of Science and Technology

This paper describes a technique to estimate surface-based duct parameters by using a simple ray tracing/correlation method. The approach is novel in that it incorporates the Spearman rank-order correlation scheme between the observed surface clutter and the surface ray density for a given propagation path. The simulation results and the real data results both demonstrate the ability of this method to estimate surface-based duct parameters. Compared with the results obtained by a modified genetic algorithm combined with the parabolic wave equation, the results retrieved from the ray tracing/correlation scheme show a minor reduction in accuracy but a great improvement on computation time. Therefore the ray tracing/correlation method might be used as a precursor to more sophisticated and slower techniques, such as genetic algorithm and particle filters, by narrowing the parameter search space and providing a comprehensive and more efficient estimation algorithm.

关键词： ray tracing Spearman rank correlation surface-based duct radar clutter

Inversion for atmosphere duct parameters using real radar sea clutter

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Chinese Physics B 2012年第2期21卷 618-623页

作者： Sheng Zheng Fang Han-Xian Institute of Meteorology PLA University of Science and TechnologyNanjing 211101China Sate Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China

This paper addresses the problem of estimating the lower atmospheric refractivity （M profile） under nonstandard propagation conditions frequently encountered in low altitude maritime radar applications. The vertical structure of the refractive environment is modeled using five parameters and the horizontal structure is modeled using five parameters. The refractivity model is implemented with and without a priori constraint on the duct strength as might be derived from soundings or numerical weather-prediction models. An electromagnetic propagation model maps the refractivity structure into a replica field. Replica fields are compared with the observed clutter using a squared-error objective function. A global search for the 10 environmental parameters is performed using genetic algorithms. The inversion algorithm is implemented on the basis of S-band radar sea-clutter data from Wallops Island, Virginia （SPANDAR）. Reference data are from range-dependent refractivity profiles obtained with a helicopter. The inversion is assessed （i） by comparing the propagation predicted from the radar-inferred refractivity profiles with that from the helicopter profiles, （ii） by comparing the refractivity parameters from the helicopter soundings with those estimated. This technique could provide near-real-time estimation of ducting effects.

关键词： atmosphere duct radar clutter refractivity from clutter genetic algorithm

Robust Centralized CFAR Detection for Multistatic Sonar Systems

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Chinese Journal of Electronics 2021年第2期30卷 322-330页

作者： LU Shuping DING Feng LI Ranwei Hangzhou Applied Acoustic Research Institute

This paper proposes a novel centralized Constant false alarm ratio(CFAR) detector for multistatic sonar systems. The detector employs the idea of Variability index(VI) CFAR detection, to adaptively select the matched detection algorithm in diversified undersea environments. All the echo data from mutistatic sonar receivers are transmitted into the centralized fusion center. Firstly, the background statistics of reference cells from different nodes are analyzed. Then choose one appropriate centralized detection algorithm according to the background statistics, which refers to the centralized Cell averaging CFAR(CA-CFAR), greatest of CFAR, order statistic CFAR detection *** performance of the proposed detector is analyzed by computer simulation and measured sonar data. The results show that, compared to the centralized CA-CFAR detector, the introduced centralized detector achieves a better robustness in multiply heterogeneous undersea environments.

关键词： appropriate centralized detection algorithm order statistic CFAR detection algorithms matched detection algorithm robust centralized CFAR detection diversified undersea environments mutistatic sonar receivers measured sonar data centralized Cell averaging CFAR multiply heterogeneous undersea environments echo data centralized CA-CFAR detector signal detection radar detection reference cells introduced centralized detector radar clutter multistatic sonar systems statistical analysis Variability index CFAR detection sensor fusion background statistics Constant false alarm ratio detector centralized fusion center object detection target tracking

Fractal detector design and application in maritime target detection

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Journal of Systems Engineering and Electronics 2017年第1期28卷 27-35页

作者： Xinglin Shen Zhiyong Song Yongfeng Zhu Qiang Fu ATR Key Laboratory National University of Defense TechnologyChangsha 410073China

The fractal properties of sea clutter are proposed and applied to the maritime target detection. Calculation of the measured data shows that, the Hurst exponent of the sea clutter with targets and the sea clutter without targets are different, which enables us to detect low-observable targets within the sea clutter. This paper explains the reason why the Hurst exponent can distinguish the presence or absence of targets in theory and proposes a fractal detector based on the Hurst exponent. Comparing the fractal detector proposed in this paper to the energy detector by the detection results of 140 frames data of the real sea clutter, it is demonstrated that the fractal detection method has a better detection performance. In order to get systemic conclusions, the new sea clutter data with different signal-to-clutter ratios (SCRs) are constructed in the way that add the sea clutter data with targets to the pure sea clutter data. The results show that the fractal detection method has a better performance than the statistical method on detection of maritime targets, especially maritime weak targets with low SCR. © 1990-2011 Beijing Institute of Aerospace Information.

关键词： Fractals radar clutter Target tracking

Novel polarimetric detector for target detection in heterogeneous clutter

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Journal of Systems Engineering and Electronics 2016年第6期27卷 1135-1141页

作者： Xu Cheng Longfei Shi Yuliang Chang Yongzhen Li Xuesong Wang State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Engineering National University of Defense Technology

A detection of static or slowly moving targets in the inhomogeneous clutter of polarimetric radar is researched and a new detector without exploiting the training set is developed, which has a good performance against the inhomogeneous clutter. The decision rule ensures the constant false alarm rate (CFAR) with respect to the disturbance covariance matrix. Numerical results show the robustness of the proposed method against the inhomogeneous clutter. © 2016 Beijing Institute of Aerospace Information.

关键词： clutter (information theory) Covariance matrix Numerical methods Polarimeters radar radar clutter radar signal processing Signal processing

An Algorithm for Ship Wake Detection from the SAR Images Using the Radon Transform and Morphological Image Processing

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Journal of Systems Engineering and Electronics 2001年第4期12卷 7-12页

作者：金亚秋王世庆 Center for Wave Scattering and Remote Sensing School of Information Science and Technology Fudan University Shanghai 200433 P. R. China

Using the Radon transform and morphological image processing, an algorithm for ship's wake detection in the SAR (synthetic aperture radar) image is developed. Being manipulated in the Radon space to invert the gray-level and binary images, the linear texture of ship wake in oceanic clutter can be well detected. It has been applied to the automatic detection of a moving ship from the SEASAT SAR image. The results show that this algorithm is well robust in a strong noisy background and is not very sensitive to the threshold parameter and the working window size.

关键词： Algorithms Image processing Mathematical transformations radar clutter radar target recognition Spurious signal noise Synthetic aperture radar

Research on the Problem of Sample Support in STAP

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Chinese Journal of Aeronautics 2001年第4期14卷 229-234页

作者：王玮李少洪毛士艺北京航空航天大学北京 100083

In the airborne radar space-time adaptive processing (STAP), the interference covariance matrix must be estimated from the IID samples which are always limited in practice. Aimed at this problem, this paper studies the combination of the forward-backward averaging (FB), diagonal loading (DL) and the reduced-rank processing to reduce the required sample number as much as possible. Through analysis and simulations, it is demonstrated that by using proper reduced-rank processing, combined with FB and DL, the required sample number can be largely reduced to even 3-5 samples.

关键词： Adaptive filtering Antennas Computer simulation Eigenvalues and eigenfunctions Matrix algebra radar clutter Signal to noise ratio