【作者】 赵孔瑞；

【导师】 权太范； 于长军；

【作者基本信息】 哈尔滨工业大学 ， 信息与通信工程， 2014， 博士

【摘要】 高频地波雷达(HFSWR)能够超视距探测海上舰船和飞机目标，对于我国海防和海上交通管制现代化建设具有重要意义。由于HFSWR构成仰角窄波束困难，不能直接提供飞行目标高度信息，因而无法判别飞行目标的高度属性，即无法判别目标的视距/超视距属性。针对单基地HFSWR目标飞行高度估计精度低、不稳定、可信度差的问题，本研究提出双基地HFSWR飞行目标高度估计新方法，重点研究飞行目标高度属性判别和高度估计算法，推动本成果在飞行目标类型识别和目标威胁度估计等领域的应用。本文主要研究内容如下：1.首先理论分析垂直极化电磁波传播衰减基本原理。基于Rotheram传播衰减模型，重点研究垂直极化电磁波在低空区域和高空区域上的传播衰减特征。目标信号回波强度是与低空飞行目标高度估计有关的重要信息，目标RCS作为影响目标飞行高度估计精度的重要参量，本文还对高频地波雷达飞行目标RCS随姿态角的变化特征进行研究。2.双基地高频地波雷达低空飞行目标高度估计研究。传统低空飞行目标高度估计模型在高度上是不完全可观测的，导致高度估计存在多解问题。本研究将感兴趣的高度区间划分为多个高度子区间，每个高度子区间上构建一个不存在多解问题的滤波模型，最后通过加权求和得到高度估计结果。针对目标RCS起伏问题，本研究利用AR模型对目标RCS起伏分量建模，减小目标RCS起伏对高度估计的影响。3.基于斜距、方位和信号回波强度信息的高空飞行目标高度估计研究。目标在高空飞行状态下一般飞行高度较高，电波传播衰减在高度方向上变化很小。因而信号回波强度不能应用于目标飞行高度估计。因此，本研究利用T/R站和R站接收到的目标斜距、方位和信号回波强度构建高空飞行目标高度组合估计算法。在该高度估计算法中，利用目标斜距和方位信息估计目标飞行高度，利用信号回波强度信息估计目标RCS。4.飞行目标高度属性判别与高度估计研究。本研究目的是在判别目标视距/超视距属性的同时，并估计目标飞行高度信息。目前的飞行目标高度估计方法只能适用于高空或低空飞行目标，而且假定目标的视距/超视距属性是已知的。但是在真实场景下，目标高度属性信息是未知的。因此，本研究利用目标高度属性判别与高度估计相互依赖、相互影响的特点，提出一种目标高度属性判别与高度估计算法。该算法估计出目标具体飞行高度信息，并根据目标高度信息和距离信息判别目标的视距/超视距属性。5.高频地波雷达飞行目标高度属性判别算法。在工程应用中，最为关心的是希望能够直接、快速判别目标的高度属性信息(视距/超视距属性信息)，这远比估计目标的具体飞行高度更有实际应用意义。基于上述工程设计思想，本研究重点解决高频地波雷达飞行目标的高度属性判别问题，构建目标高度属性判别算法和准则，并提出一种高度属性可信度计算方法。此外，针对信号回波强度存在固定偏差问题，本研究提出一种基于余弦相似度的高度属性判别可信度计算方法，从而减小信号回波强度固定偏差的影响。更多还原

【Abstract】 High frequency surface wave radar (HFSWR) transmits vertically polarized electromagnetic wave to detect surface vessels and low-flying aircraft at ranges far beyond the visible horizon, which is essential for the coast defence and marine traffic control. The operation frequency in high frequency (HF) band makes it difficult to form a narrow beam on elevation. HFSWR traditionally cannot detect the target altitude information and lacks the capability to identify the target flight modes, such as over the horizon or within the line of horizon. The current altitude estimation methods in monostatic HFSWR always yield low accurate and unstable results. Therefore, in this dissertation, the novel approaches are proposed to estimate target altitude and identify the flight mode with bistatic HFSWR. The performance of the proposed approach is evaluated with real trials. The research in this dissertation would promote the application of bistatic HFSWR in target classification and marine traffic control fields. The main contents of the dissertation are summarized as following:1. The propagation attenuation mechanism of the ground wave at different altitude intervals is analyzed with Rotheram model. The propagation attenuation of ground wave indicates distinct characteristics at diffferent altitude intervals, which is the fundamental principle of target altitude estimation and flight mode identification in HFSWR. Besides, target RCS is an crucial parameter for the altitude estimation of low-flying target. The variation property of RCS on different attitudes is also studied.2. An altitude estimation model is proposed for the low flying target with bistatic HFSWR. The incomplete observability of the traditional altitude estimation model leads to poor performance for altitude estimation. A novel model is proposed to estimate the altitude of the low-flying target with multiple model approach. In this new model, the altitude interval of interest is divided into several subintervals. An independent estimation model is constructed on each subinterval. The ultimate altitude estimation result is achieved by weighted summation. Besides, autoregressive model is also incorporated to eliminate the effection of the RCS fluctuation on altitude estimation. 3. An altitude estimation model with the range, azimuth and target echo is presented for the high-flying target. Both target range and azimuth are available information for the target altitude estimation of high-flying target. Target echo amplitude does not benefit the altitude estimation as it is independent on altitude, which is only utilized to estimate target RCS. An altitude and RCS estimation model set is proposed with the target range, azimuth and echo amplitude information received by T/R-R HFSWR. The model set contains three different estimation models. Each model is completely observable to the state.4. Simultaneous target altitude and flight mode identification. The objective of this research is to identify the flight mode as well as estimate the target altitude. With the property that the estimation and identification processes are mutually dependent, an integrated method named simultaneous identification and estimation(SIE) is proposed by applying two level multiple model approach to the flight mode probability mass function(pmf) and state probability density function(pdf) simultaneously. The multiple model approach incorporated in SIE is different from the traditional interacting multiple model (IMM). It is applied at two levels: within each mode-conditioned estimation model set and across all the mode-conditioned estimation model sets. Simulations and real trials demonstrate the performance of the proposed SIE method.5. Flight mode identification algorithm in HFSWR. In practical engineering applications, it is preferable and more promising to identify the flight mode directly than estimate the specific target altitude for threat assessment. Thus a flight mode identification model is proposed with the distinct propagation attenuation characteristics on the low and high altitude intervals. A certainty factor value is also derived to evaluate the accuracy of the flight mode identification, in which cosine similarity is involved to eliminate the impact of the target echo amplitude errors for flight mode identification.更多还原