基于自适应时域处理的展宽海杂波背景下目标检测

发布时间：2018-03-08 06:30

本文选题：高频天波超视距雷达　切入点：展宽海杂波　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：天波超视距雷达具有探测范围远、监测范围大等优点，是预警系统的重要组成部分；同时也是各国监测海洋专属经济区的常用手段。然而对于低速运动的目标的检测问题，由于电离层相径扰动的存在使得海杂波回波谱展宽，又由于舰船目标的Doppler频移和海杂波一阶布拉格峰频率相差不大，导致展宽的海杂波极易淹没舰船目标，严重影响天波雷达对舰船目标的探测能力。海杂波展宽的原因除了电离层相径扰动之外还有电离层造成的多径传播、多模传播、幅度衰落等，这些因素往往和电离层相径扰动叠加在一起，使得海杂波多普勒谱展宽的原因非常复杂，给展宽海杂波的抑制和被展宽海杂波淹没目标的检测带来巨大障碍。以往对展宽海杂波回波谱的抑制主要采用对电离层相径扰动进行补偿校正的方法，这类方法往往仅在慢相径扰动的情况下才能取得一定的效果。然而，实际工程中海杂波展宽的原因不仅仅是由于存在慢相径扰动，这导致这类算法的应用受到极大限制。进入二十一世纪，美国Duke大学从广义似然检测的角度出发对被展宽海杂波淹没的舰船目标进行检测，将自适应匹配滤波等算法应用到天波体制雷达系统中，通过从临近距离分辨单元选择杂波训练样本实现对展宽海杂波的抑制。然而这类算法存在两个显著缺陷，一是运算复杂度较大，不符合实时性运算要求；二是对天波雷达来说，由于其距离分辨力较差，加上海态变化等原因，使得从临近距离分辨单元选取的训练样本往往不能很好的表征当前待处理分辨单元的杂波特性，因而算法性能较差。本文针对这两种问题提出了较好的解决方法，主要内容如下： (1)对天波雷达海杂波产生的机理，海杂波Doppler谱展宽的原因进行了分析，并简要介绍了几种常见的电离层相径扰动校正方法，然后分析了这类方法的特性。 (2)分析了美国杜克大学基于目标的平稳性比海杂波平稳性强而提出的一种广义似然比检测算法，并通过仿真实验对该算法性能进行了分析。 (3)提出了一类基于平滑处理的目标检测算法，该算法与传统时域自适应匹配滤波算法相比可以大大降低计算复杂度，其中复乘法计算次数降低五个数量级左右，使得算法符合工程实时性运算要求。 (4)针对从临近距离分辨单元所选择训练样本不能很好表征杂波特性的难点，本文提出一种基于空时级联处理的目标检测算法，该算法通过空域陷波处理滤掉雷达回波中的目标信息，从当前距离分辨单元获取训练样本，因而能够较好的实现对展宽海杂波的抑制，，然后通过所提的基于平滑处理的方法实现对被淹没目标的检测。
[Abstract]:Sky wave over-the-horizon radar has the advantages of long detection range and large monitoring range. It is an important part of the early warning system, and is also a common means of monitoring the ocean exclusive economic zone. However, for the detection of low-speed moving targets, it is also a common method of monitoring the ocean exclusive economic zone. Due to the existence of the ionospheric phase diameter disturbance, the echo spectrum of sea clutter is widened, and the Doppler frequency shift of ship target and the frequency of first order Bragg peak of sea clutter are not different. In addition to ionospheric phase diameter disturbances, there are also multipath propagation, multimode propagation and amplitude fading caused by ionosphere. These factors are often superimposed with ionospheric phase diameter disturbances, which make the reasons for broadening the Doppler spectrum of sea clutter very complicated. It brings great obstacles to the suppression of broadened sea clutter and the detection of submerged targets. In the past, the method of compensating and correcting the ionospheric phase diameter disturbance was used to suppress the echo spectrum of broadened sea clutter. This kind of method can only get certain effect under the condition of slow phase path disturbance. However, the reason of the clutter broadening in practical engineering is not only because of the existence of slow phase path perturbation, but also because the application of this kind of algorithm is greatly limited. In 21th century, Duke University of the United States started from the point of view of generalized likelihood detection to detect ship targets submerged by extended sea clutter, and applied adaptive matched filtering and other algorithms to the radar system of sky wave system. The clutter training samples are selected from the near range resolution unit to suppress the outspread sea clutter. However, there are two significant shortcomings in this algorithm, one is that the computation complexity is large, which does not meet the real-time operation requirements, and the other is the sky wave radar. Because of the poor range resolution and the variation of the Shanghai state, the training samples selected from the near range resolution unit often can not well characterize the clutter characteristics of the current resolution units to be processed. Therefore, the performance of the algorithm is poor. In this paper, a better solution to these two problems is proposed, the main contents are as follows:. In this paper, the mechanism of sea clutter generation in sky-wave radar and the cause of Doppler broadening are analyzed, and several common methods for correction of ionospheric phase diameter disturbance are briefly introduced, and then the characteristics of these methods are analyzed. (2) A generalized likelihood ratio detection algorithm proposed by Duke University is analyzed, and its performance is analyzed by simulation experiments. A class of target detection algorithm based on smoothing processing is proposed. Compared with the traditional time domain adaptive matched filtering algorithm, this algorithm can greatly reduce the computational complexity, in which the number of times of complex multiplication is reduced by about five orders of magnitude. The algorithm meets the requirements of engineering real-time operation. 4) aiming at the difficulty that the training samples selected from the near range resolution unit can not well characterize the clutter characteristics, a target detection algorithm based on space-time cascade processing is proposed in this paper. The algorithm can filter the target information in radar echo by spatial notch processing and obtain training samples from the current range resolution unit. Then the submersible targets are detected by the proposed smoothing processing method.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN958.93

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