Wideband Radar Target Research Articles

Knowledge-Aided Wideband Radar Target Detection in the Heterogeneous Clutter

In this paper, the problem of wideband radar target detection in the heterogeneous environment is addressed. The wideband radar return of target with range migration is characterized as a subband model, and the heterogeneous clutter is described with a hierarchical Bayesian model. Both the prior knowledge of the clutter power and the covariance matrix and the dependence of the primary data and the secondary data are characterized with the inverse gamma and the inverse complex Wishart distribution, respectively. Based on the target and the clutter models, knowledge-aided maximum posterior ratio test (KAMAPRT), knowledge-aided Rao (KARao) test and knowledge-aided Wald (KAWald) test for wideband radar target detection in heterogeneous clutter are proposed. Finally, the performance of the proposed detectors is evaluated by simulations with both the simulated clutter generated by the probability model and the synthesized clutter from a real synthetic aperture radar (SAR) complex image. The results show that the proposed knowledge-aided detectors are effective for wideband radar target detection in the heterogeneous clutter.

Bayesian Detectors for Wideband Radar Target With Range Walking in Compound Gaussian Clutter

In this paper, the problem of the wideband radar target detection with the range walking in compound Gaussian clutter without the secondary data is addressed. The wideband radar target return with the range walking is represented as a canonical linear model in the multi-rank subspace, and the clutter is modeled as a two-dimensional random process with separable complex inverse Wishart distributed random covariance matrices in the pulse and range-frequency domains. The generalized likelihood ratio test (GLRT), the Wald test and the Rao test based on the above target and clutter models are designed under the Bayesian framework. The Laplace approximation is adopted to compute the second-kind confluent hypergeometric function of matrix argument (SKCHFMA) in the proposed detectors. Finally, the performance of the detectors is validated by the simulations.

A target echo simulation method for wideband LFM-PRPC signals based on segmentation processing

ABSTRACT To address the target echo simulation problem for linear frequency-modulated and pseudorandom phase-coded (LFM-PRPC) signals, this letter proposes a target echo reconstruction method based on segmentation processing. We treat the phase mutation points of an LFM-PRPC pulse signal as the basis for segmentation, approximately dividing the time-domain signal into several narrowband, short-term pulse signals, and then calculate the target echo signal corresponding to each pulse. Finally, we reconstruct the full pulse of the wideband target echo signal. This method not only reflects the intrapulse modulation characteristics of a radar signal and the wideband electromagnetic scattering characteristics of the target but also effectively improves the real-time performance of wideband radar target echo signal calculations without reducing the calculation accuracy. Moreover, it is applicable to both uniform and pseudorandom (nonuniform) coded signals. The results prove the reliability and feasibility of the proposed method.

Research on Online Calibration Technology of Wideband Radar Target Simulation System

Research on Online Calibration Technology of Wideband Radar Target Simulation System

Analytical Model and Real-Time Calculation of Target Echo Signals on Wideband LFM Radar

In wideband radar system testing and performance evaluation, target echo simulation should simultaneously meet real-time and high-precision requirements. In this paper, we focus on the wideband linear frequency modulated (LFM) radar signal, derive the echo signal time-domain analytical expression based on the multiscattering center model and propose a high-precision real-time echo simulation calculation method. Regarding the low model reliability and poor versatility problems in the current wideband radar target calculation, the analytical model proposed here truly reflects the inner-pulse modulation characteristics of the radar transmit signal and the wideband electromagnetic scattering characteristics of the target. Current wideband radar target signal calculation accuracy and real-time performance are also difficult to balance. Considering this problem, the wideband radar target echo analytical model proposed in this paper avoids the large amount of calculations required for the full numerical calculation and effectively improves the calculation accuracy and real-time performance of wideband radar target echo signal calculations without reducing calculation accuracy. The real-time calculation method involves elaborate amplitude-phase control. Simulation analysis and experimental verification confirmed the reliability and validity of these results. These research results have important theoretical significance and practical application value in the field of hardware-in-the-loop simulation.

Knowledge-based wideband radar target detection in the heterogeneous environment

In this paper, we address wideband radar target detection in the heterogeneous environment. Firstly, a linear model of the wideband radar target return with the steering vector dispersion is established. Secondly, the heterogeneous clutter is modeled as a two-dimensional wide-sense stationary (WSS) process with inverse complex Wishart distributed random covariance matrices in the time-space and frequency domain. Then, several generalized likelihood ratio test (GLRT) based detectors are designed, some of which integrate the prior knowledge of the clutter covariance matrix with the Bayesian approach, while the others are with the heuristic approach. Finally, the performance of the detectors is evaluated by simulations, and the results show that the detectors based on the Bayesian approach outperform the other detectors.

Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

Hardware-in-the-loop (HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory (DRFM) system, the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile (HRRP) are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.

Performance Comparison of Wideband Radar Target Detection Methods

In wideband radar situation, target-spread and all scattering points back wave could be considered as the pulse train of random parameters. The wideband radar target and built the related model. Then it gave two methods of target detection, one is Energy Accumulation and the other is the IPTRP. It also presented the simulation result of these two methods performance curves. It showed that the IPTRP improved by more than 3dB in the same SNR.

Local Reconstruction Error Alignment: A Fast Unsupervised Feature Selection Algorithm for Radar Target Clustering

Observed samples in wideband radar are always represented as nonlinear points in high dimensional space. In this paper, we consider the feature selection problem in the scenario of wideband radar target clustering. Inspired by manifold learning, we propose a novel feature selection algorithm, called Local Reconstruction Error Alignment (LREA), to select the features that can best preserve the underlying manifold structure. We first select the features that minimize the reconstruction error in every neighborhood. Then, we apply the alignment technique to extend the local optimal feature sequence to a global unique feature sequence. Experiments demonstrate the effectiveness of our proposed method.

Waveform design for wideband radar target recognition based on eigensubspace projection

Transmission waveform design based on the target and the surrounding environment plays an important role in wideband target recognition radar, which could be helpful to enlarge the separation between the received echoes of different targets. However, precise prior knowledge of target–radar orientation is usually difficult to obtain, whereas target impulse response is sensitive to target–radar orientation. Therefore that has become a barrier for the waveform design. In this study, the authors propose an eigensubspace projection-based method to enlarge the separation between the received echoes of different targets with additive coloured Gaussian noise, after analysing the upper bound on the error probability of multi-target recognition. Numerical results show that the proposed method is able to improve the recognition rates effectively.

Wideband Radar Spread Targets Detection in Compound Gaussian Clutter

The aim of this study is to analyze the influence of neglecting compound Gaussian clutter texture on wideband radar targets detection. The texture of compound-Gaussian clutter is researched, the Probability Density Function (PDF) expression of G0 distributed clutter is proposed. The optimal detection statistics treats the texture of G0 distributed clutter as a certain function is derived. As contrast, another detector neglects the clutter texture is derived. The numerical results are presented by means of Monte Carlo simulation strategy. Assume that cells of signal components are available. Those secondary data are supposed to possess either the same covariance matrix or the same structure of the covariance matrix of the cells under test. The simulation results highlight that the performance loss of the two detectors in different roughness parameter, the result shows the loss less than 2dB due to the texture is neglected and adaptively estimating the covariance matrix.

Wideband Radar Target Detection Theory in Coherent K Distributed Clutter

The aim of this study is to analyze the influence of neglecting K distributed clutter texture on wideband radar distributed targets detection. At first, the texture and the speckle of K clutter are researched and the Probability Density Function (PDF) of K clutter and its texture are derived, then the optimal detector by Neyman-Pearson (NP) is proposed, by contrast, another detector-Suboptimum Generalized Likelihood Ratio Test (GLRT) neglecting the clutter texture is given. Next, the estimation of covariance matrix is introduced. Finally, the numerical results are presented by means of Monte Carlo simulation strategy and the simulation results highlight that the performance loss of the 2 detectors in different shaping parameter, the result shows that the performance loss of the detector in K distributed clutter less than 1 db due to the texture is neglected and adaptively estimating the covariance matrix and the K clutter texture can be neglected on wideband radar targets detection.

An Improved Wavelet Denoising Algorithm for Wideband Radar Targets Detection

A novel denoising technique based on wavelet transform modulus maxima (WTMM) is proposed for processing wideband radar spread targets detection signal in a clutter environment. Combined with the improved adaptive Bayes–Shrink threshold and Lipschitz exponents, we propose the path pruned approach at each scale terms as full-scale to split the signal. The estimation of WTMM over each scale has been optimized, thus, the signal and the noise can be split effectively. Additionally, to improve the computational efficiency, a fast method based on a piecewise polynomial interpolation algorithm is applied for the split signal reconstruction. Statistical results are quite promising and perform better than the conventional denoising algorithms: compared with the classical WTMM algorithm, the improved WTMM full-scale denoising algorithm not only increases the signal-to-noise (SNR) ratio by over 10 % but also reduces the processing time by 88 % and reduces the root-mean-square-error (RMSE) by over 35 %. More generally, the proposed algorithm has better performance than that of several typical algorithms in its denoising quality and singularity detection.

Hough-transform-based Detector for Wideband Radar Target

该文针对宽带雷达目标距离单元走动、具有强距离单元的特性，提出了一种基于Hough变换的目标检测算法(HD)。该算法分为两步：在第1步中，对过一级门限的高分辨距离像数据做Hough变换，并对Hough参数空间的所有数据做相应的累积分布函数(CDF)映射；在第2步中求出各个角度若干个最大值的和，并对这些和值做CDF映射，选出最大的映射和值作为检测算子。3类飞机实测数据的实验结果表明，与基于散射点密度的广义似然比检测算法相比，该方法检测性能至少有1.3 dB的提高。

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

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