天波OTH雷达电离层相位污染校正与机动目标探测研究

发布时间：2019-06-14 02:06

【摘要】：天波超视距(Over-The-Horizon,OTH)雷达通过向空中发射高频电磁波,接收电离层反射的回波实现目标的探测。天波OTH雷达具有探测距离远、效费比高以及“四抗”的特点,使其被广泛地应用于远程战略预警、缉毒走私、空海交通管理、环境遥感、核爆炸监测等领域。天波OTH雷达具有很多优势,同时也存在许多不足和挑战。首先,由于其通过电离层反射的工作机制,回波信号会受到电离层相位污染,使强大的海杂波谱展宽,给舰船目标的检测带来了困难。在者,目标的机动性会使回波的多普勒频谱扩展,OTH雷达长相干积累时间加重了扩展程度,这对目标参数的估计是不利的。另外,在天波OTH雷达计算目标参数时,没有考虑电离层的先验误差信息,忽略了电离层探测设备的误差,使得估计的参数不够精确。围绕以上问题,本文展开了深入研究,主要工作如下:(1)基于最大似然法的电离层相位污染校正算法提出了一种基于最大似然法的天波OTH雷达电离层相位污染校正算法。该方法将Bragg峰建模为相位多项式,通过最大化信号的似然函数来实现污染相位的估计和校正。为了避免最大似然法中的矩阵求逆运算,该算法进一步将最大似然问题转化为最小二乘问题,再通过遗传算法求解相位系数。实验结果表明,该算法比已有算法的校正效果更好。(2)基于Hankel矩阵分解的机动目标探测算法提出了一种基于Hankel矩阵分解的天波OTH雷达机动目标探测方法。该算法将目标参数的估计问题转化为基于线性主成分分析的凸优化问题,将回波信号构造为Hankel矩阵并进行矩阵分解,然后分别求解低秩矩阵和稀疏矩阵的时频分布,从而实现多目标同时探测。本文给出仿真结果验证了该算法比已有算法具有更高的精度。(3)目标与电离层参数联合估计算法提出了一种天波OTH雷达目标与电离层参数联合估计算法。该算法利用了电离层探测设备的先验误差信息,把待估参数设置为目标与电离层联合参数,利用解析模型将电离层探测设备误差转化为目标参数误差,从而实现联合估计。仿真结果表明,该方法可以明显提升已有算法的精度,比传统算法更有优势。
[Abstract]:The sky wave over-the-horizon (Over-The-Horizon,OTH) radar can detect the target by transmitting high frequency electromagnetic wave into the air and receiving the echo reflected by the ionosphere. Tianbo OTH radar is widely used in remote strategic early warning, anti-drug smuggling, air and sea traffic management, environmental remote sensing, nuclear explosion monitoring and other fields because of its long detection distance, high efficiency and cost ratio and "four resistance" characteristics, which makes it widely used in remote strategic early warning, anti-drug smuggling, air and sea traffic management, environmental remote sensing, nuclear explosion monitoring and so on. Sky wave OTH radar has many advantages, but also has many shortcomings and challenges. First of all, because of the working mechanism of its reflection through the ionosphere, the echo signal will be polluted by the ionosphere phase, which widens the powerful sea impurity spectrum and brings difficulties to the detection of ship targets. However, the maneuverability of the target will cause the Doppler spectrum spread of the echo, and the apparent coherence accumulation time of OTH radar will increase the degree of spread, which is disadvantageous to the estimation of target parameters. In addition, when the sky wave OTH radar calculates the target parameters, the prior error information of the ionosphere is not taken into account, and the error of the ionosphere detection equipment is ignored, so that the estimated parameters are not accurate enough. Around the above problems, the main work is as follows: (1) based on the maximum likelihood method, an ionosphere phase pollution correction algorithm based on the maximum likelihood method is proposed, which is based on the maximum likelihood method for the correction of ionosphere phase pollution in sky wave OTH radar. In this method, the Bragg peak is modeled as a phase polynomial, and the pollution phase is estimated and corrected by maximizing the likelihood function of the signal. In order to avoid the matrix inversion in the maximum likelihood method, the maximum likelihood problem is further transformed into the least square problem, and then the phase coefficient is solved by genetic algorithm. The experimental results show that the correction effect of this algorithm is better than that of the existing algorithms. (2) A maneuvering target detection algorithm based on Hankel matrix decomposition is proposed. A maneuvering target detection method of sky-wave OTH radar based on Hankel matrix decomposition is proposed. In this algorithm, the estimation problem of target parameters is transformed into a convex optimization problem based on linear principal component analysis. The echo signal is constructed as Hankel matrix and decomposed into matrix, and then the time-frequency distribution of low rank matrix and sparse matrix is solved respectively, so as to realize the simultaneous detection of multiple targets. In this paper, the simulation results show that the algorithm has higher accuracy than the existing algorithm. (3) A joint estimation algorithm of target and ionosphere parameters for sky-wave OTH radar is proposed. The algorithm makes use of the prior error information of the ionosphere detection equipment, sets the parameters to be estimated as the joint parameters of the target and the ionosphere, and converts the errors of the ionosphere exploration equipment into the target parameter errors by using the analytical model, so as to realize the joint estimation. The simulation results show that this method can obviously improve the accuracy of the existing algorithms, and has more advantages than the traditional algorithms.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN958.93

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