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Generalized adaptive subspace detector for range-Doppler spread target with high resolution radar

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Science China(Information Sciences) 2011年第1期54卷 172-181页

作者： DAI FengZhou,LIU HongWei & WU ShunJun national lab of radar signal processing,Xidian University,Xi’an 710068,China national lab of radar signal processing Xidian University

A generalized adaptive subspace detector for range-Doppler spread target(RDST-GASD)in the non-Gaussian clutter is derived in this *** subspace model of multi-pulse wideband radar target returns is established in the frequency-slow time *** clutters are modeled as nonhomogeneous spherically invariant random vectors(SIRVs);that is,the power of the clutter is different from one range cell to *** clutter covariance matrix is estimated with the secondary *** constant false alarm rate(CFAR)property of RDST-GASD with respect to both the power and the covariance matrix of the clutter is demonstrated *** that there is target range walking across range cells during a coherent processing interval(CPI)for wideband radar,the RDST-GASD does range alignment to the multiple returns of the target in a *** a result,the coherent integration is implemented and the detection performance is improved.

关键词： high resolution radar range-Doppler spread target range walking SIRV adaptive subspace de- tector

An eigenstructure-based 2D DOA estimation method using dual-size spatial invariance array

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Science China(Information Sciences) 2011年第1期54卷 163-171页

作者： YANG XueYa,CHEN BaiXiao & CHEN YunHai national Key lab of radar signal processing,Xidian University,Xi’an 710071,China national Key lab of radar signal processing Xidian University

A sparse planar array vertically placed in y-z plane is proposed to improve the angle estimation accuracy of sources in low angle region with reflection *** two sizes of spatial invariances along both dimensions,the array estimates the azimuth and elevation angles using unitary ESPRIT(estimation of signal parameters via rotational invariance techniques).The first spatial invariance with a displacement of half-wavelength yields unambiguous coarse estimates of high-variance,while the second spatial invariance with much larger a displacement of subarrays obtains cyclically ambiguous fine estimates of *** final estimates are obtained by disambiguating fine estimates with coarse estimates.A novel pairing scheme is proposed to pair both the azimuth and elevation,coarse and fine angle estimates of the same *** addition, a new method is presented to calculate 2D angles,which substitutes the estimated elevation angle into the sin relative to the y-axis to get the azimuth *** real-valued processing and array aperture extension, the new DOA measuring method de-correlates the multipath signals and enhances angle resolution with no extra antennas and computational *** results show the effectiveness of the proposed technique and its advantages over the conventional methods.

关键词： DOA estimation sparse array correlated signals unitary ESPRIT dual-size spatial invariances

Double-characters detection of nonlinear frequency modulated signals based on FRFT

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Science China(Information Sciences) 2011年第1期54卷 136-145页

作者： XU ShuWen,SHUI PengLang & YANG XiaoChao national laboratory of radar signal processing,Xidian University,Xi’an 710071,China national laboratory of radar signal processing

In many practical applications,signals to be detected are unknown nonlinear frequency modulated (FM)and are corrupted by strong *** phase histories of the nonlinear FM signals are assumed to be unknown smooth functions of time,which are usually poorly modeled or cannot be modeled at all by a small number of *** of the lack of phase model,a nonparametric detection method is proposed based on successive fractional Fourier transform and double-characters *** detection process goes in three ***,an image is constructed by the fractional Fourier transforms of successive angles in one period. Then,the threshold procedure is utilized to transform the image into a binary *** the multiple median filtering,the binary image is refined where the isolated noise pixels are ***,two complementary features are extracted from the refined image,and a double-characters detector is proposed to decide whether the target is present or *** simulation experiments to three polynomial phase signals with different orders and a sinusoidal phase signal show that the proposed detection method is effective and robust.

关键词： fractional Fourier transform double-characters detector nonparametric detection multiple median filtering

Real-domain GMUSIC algorithm based on unitary-transform for low-angle estimation

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Journal of Systems Engineering and Electronics 2014年第5期25卷 794-799页

作者： Zheng Liu Yuanyuan Wang Yunhe Cao national laboratory of radar signal processing Xidian University

In order to realize the elevation angle estimation for low-altitude targets at a low computational cost, a generalized multiple signal classification （GMUSIC） algorithm based on unitary transform is proposed, i.e., the DU-GMUSlC algorithm. Firstly, the covariance matrix of received data is used to construct the Centro- Hermitian matrix. Then, the real-domain GMUSIC algorithm is used to implement the initial angle estimation, and the multipath attenuation coefficient is calculated in succession. Finally, the attenuation coefficient is taken into account in the GMUSIC method to carry out the secondary angle estimation which is beneficial to further improvement of the angle estimation accuracy. This method can meet requirements of low-angle accuracy as well as lower computational burden. Simulation results prove the correctness and effectiveness of the proposed algorithm. Moreover, field experiment data are used to further validate the effectiveness of this method.

关键词： multipath effect low-angle estimation unitary transform. attenuation coefficient.

Azimuth resolution improvement for spaceborne SAR images with quasi-non-overlapped Doppler bandwidth

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Journal of Systems Engineering and Electronics 2014年第3期25卷 422-427页

作者： Yanyang Liu Zhenfang Li Zhiyong Suo Jinwei Li Zheng Bao national laboratory of radar signal processing Xidian University

The azimuth resolution improvement problem is solved via a coherent combination of synthetic aperture radar （SAR） ima-ges with the quasi-non-overlapped Doppler bandwidth. Prior to the spectra combination, SAR images should be coregistered, while phase biases induced by topography, atmospheric propagation delays and baseline measurement errors should be calibrated. However, the coregistration accuracy suffers from large Doppler decorrelation caused by the quasi-non-overlapped Doppler band-width. Furthermore, the method used to estimate phase biases from interferogram of azimuth prefiltered SAR image pairs wil fail when there is no overlapped spectrum. The fringe simulation and maximum sharpness optimization are adopted to deal with the problems. Accordingly, a novel algorithm to coherently synthesize SAR images is presented. The experiment with the Terra SAR X-band （TerraSAR-X） satel ite data validates the performance of the presented method.

关键词： synthetic aperture radar (SAR) azimuth resolution improvement maximum sharpness optimization fringe simulation.

radar high resolution range profile recognition via multi-SV method

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Journal of Systems Engineering and Electronics 2017年第5期28卷 879-889页

作者： Long Li Zheng Liu Tao Li national laboratory of radar signal processing Xidian University

For radar high resolution range profile (HRRP) recognition, three aspects are of great importance to improve the performance, i.e. discrimination for outlier, classification for inner and an accurate description for feature space. To tackle these issues, a novel target recognition method is designed, denoted by the multiple support vectors (multi-SV) method. With the proposed method, a special framework is constructed by a treble correlate support vector model to segment the feature space to two regions with the distribution of density, and then the description and classification hyperplane for each region are achieved. Based on the support vector framework, this method needs less memory and computation complexity to fit practical radar HRRP recognition. Finally, the experiment based on the measured data verifies the excellent performance of this method.

关键词： radar target recognition high resolution range profile support vector discrimination classification

Joint compressed sensing imaging and phase adjustment via an iterative method for multistatic passive radar

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Frontiers of Information Technology & Electronic Engineering 2018年第4期19卷 557-568页

作者： Jue WANG Jun WANG national laboratory of radar signal processing Xidian University

The resolution of the multistatic passive radar imaging system(MPRIS)is poor due to the narrow bandwidth of the signal transmitted by illuminators of ***,the inaccuracies caused by the inaccurate tracking system or the error position measurement of illuminators or receivers can deteriorate the quality of an *** improve the performance of an MPRIS,an imaging method based on the tomographic imaging principle is *** the compressed sensing technique is extended to the MPRIS to realize high-resolution ***,a phase correction technique is developed for compensating for phase errors in an *** errors can be estimated by iteratively solving an equation that is derived by minimizing the mean recovery error of the reconstructed image based on the principle of fixed-point iteration *** technique is nonparametric and can be used to estimate phase errors of any *** effectiveness and convergence of the technique are confirmed by numerical simulations.

关键词： Multistatic passive radar Compressed sensing Phase adjustment Fixed-point iteration technique

Fast Transmit Beamforming for Large Planar MIMO radar

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Chinese Journal of Electronics 2020年第4期29卷 759-765页

作者： LIU Bingfan CHEN Baixiao national laboratory of radar signal processing Xidian University

A fast method of transmit beamforming for large planar Multiple-input multiple-output(MIMO)radar is *** MIMO radar with large elements,it is difficult to design a large number of orthogonal *** design a weight matrix to connect orthogonal waveforms and array *** optimize the weight matrix such that the transmit beampattern approximates the desired transmit *** introducing an auxiliary variable, a cyclic optimization algorithm based on Fast fourier transform(FFT) is proposed to obtain the optimal weight matrix, which is very efficient and can satisfy the real-time *** examples are provided to verify the effectiveness of the proposed algorithm.

关键词： MIMO radar Transmit beamforming Planar array

Low complexity robust adaptive beamforming for general-rank signal model with positive semidefinite constraint

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Frontiers of Information Technology & Electronic Engineering 2016年第11期17卷 1245-1252页

作者： Yu-tang ZHU Yong-bo ZHAO Jun LIU Peng-lang SHUI national laboratory of radar signal processing Xidian University

We propose a low complexity robust beamforming method for the general-rank signal model, to combat against mismatches of the desired signal array response and the received signal covariance matrix. The proposed beamformer not only considers the norm bounded uncertainties in the desired and received signal covariance matrices, but also includes an additional positive semidefinite constraint on the desired signal covariance matrix. Based on the worst-case performance optimization criterion, a computationally simple closed-form weight vector is obtained. Simulation results verify the validity and robustness of the proposed beamforming method.

关键词： Beamforming General-rank Low complexity Positive semidefinite(PSD) constraint Model mismatches