高频地波雷达多域协同抗电离层杂波干扰方法研究

发布时间：2018-01-05 20:11

本文关键词：高频地波雷达多域协同抗电离层杂波干扰方法研究　出处：《哈尔滨工业大学》2014年博士论文　论文类型：学位论文

【摘要】：由于工作在电磁环境复杂的短波波段,高频地波雷达容易受到短波电台、电离层杂波等各类射频干扰的影响。其中,电离层杂波是目前限制高频地波雷达生存能力的最大因素。传统高频地波雷达抗电离层杂波的方法主要使用时频域、空域和极化域的部分信息进行杂波抑制,由于未充分利用目标与杂波的全部信息,抗干扰的效果受到限制,适用范围也存在一定局限性。综合利用空域和极化信号处理的优势,实现多域协同抗干扰是解决上述问题的有效手段。本课题以空域信号处理和极化域信号处理为基础,研究了以斜投影为数学工具进行干扰抑制的方法,深入挖掘空域和极化域滤波的潜力。在此基础上,进一步研究将时频域、空域和极化域信号处理有机结合进行多域协同电离层杂波抑制的系统和方法。全文的主要研究内容如下:1、第2章中基于长期观测的大量实测数据,分析了电离层杂波在时域、多普勒域、极化域以及空域的特征,研究了电离层杂波的时间非平稳性。然后在简要介绍斜投影算子的基础上,概述了多域协同抗干扰方法的基本框架,为后续抗干扰方法研究奠定基础。2、第3章中具体研究了在空域进行干扰抑制的方法。利用空域滤波进行干扰抑制是当今高频地波雷达抑制射频干扰的主要手段,但也存在一系列的问题。首先是如何设计最优滤波器,在保持目标信号相参特性的同时实现最优的干扰抑制;其次,如何实现多干扰条件下的干扰抑制也是亟待解决的问题;此外,考虑到高频地波雷达实际系统的阵列孔径受限,往往导致常规空域滤波器无法形成足够窄的主瓣或空域凹口,当电离层杂波与目标方位较为接近时,滤波后信干比改善不理想。为解决上述问题,本章中首先以斜投影空域滤波器为基础,针对单干扰抑制问题提出了基于最优SINR准则的改进斜投影空域滤波器。斜投影空域滤波器可保证目标无失真的通过,同时在干扰方位形成空域零陷将其抑制。从而在最大程度上抑制干扰的同时保持目标信号的相参特性。特别的,这种抑制能力对位于主瓣外和主瓣内的干扰同样有效,具备抑制主瓣干扰的能力。针对斜投影空域滤波器在空间主角较小时的噪声增益较大问题,提出了基于SINR最优准则的改进斜投影空域滤波器,改善了低信噪比条件下斜投影空域滤波的SINR性能。针对多干扰抑制问题,本文提出了斜投影空域滤波的多干扰抑制算法,针对多个方位同时存在电离层杂波的情况,在距离多普勒域进行干扰抑制。该方法通过构造多个并行的斜投影空域滤波器,在干扰方位分别形成相应的空域零陷以期分别抑制多个电离层杂波。以此为基础,在距离多普勒域进行逻辑积操作,从而将所有干扰同时抑制掉。进一步的,本章提出了一种距离多普勒域的主瓣干扰抑制空域滤波算法,用于解决干扰方位无法准确估计时的干扰抑制问题。该算法在多干扰抑制算法的基础上,一方面增加空域凹口的数量,以覆盖更多的非期望方向;另一方面利用单个斜投影空域滤波器可抑制主瓣内干扰的特点,通过将部分凹口设置在主瓣内实现了主瓣干扰抑制。3、第4章中研究极化域干扰抑制方法。基于斜投影的极化滤波器由于无需满足极化子空间的正交性,在干扰极化抑制方面具有很大的潜力,但目前斜投影极化滤波器主要在时域和频域进行。本文将其进一步拓展到距离多普勒域和距离时间域。首先,提出了距离多普勒域电离层杂波抑制算法。针对功率较低的电离层杂波,在距离多普勒域设定杂波样本窗进行极化估计和杂波抑制;其次,提出了距离时间域电离层杂波抑制算法,针对能量和非平稳性较强的电离层杂波在距离时间域进行分组估计和极化抑制。最后,在两种算法的基础上提出了电离层杂波综合抑制的方案,在极化域实现了对非平稳电离层杂波的有效抑制。4、第5章中研究多域协同干扰抑制方法,提出了斜投影空域极化域协同滤波干扰抑制算法并对高频地波雷达电离层杂波干扰进行了抑制。斜投影空域滤波和极化滤波具有各自的特点,但是当目标与杂波方位完全重合或者极化状态接近时,上述两种滤波器的性能都会变差。为解决这一问题,论文中利用极化敏感阵列同时获取信号空域和极化域信息,并以此为基础构建了多域协同系统模型。文中首先研究了基于极化敏感阵列的斜投影多域协同滤波器的优势和特点;其次,研究了极化敏感阵列信号参数估计的等效方法;再次,研究了具有极化辅助通道的高频地波雷达天线阵与极化敏感阵列之间的关系;最后,结合距离多普勒域的斜投影极化滤波和斜投影空域滤波算法的思想,提出了斜投影空域极化域协同滤波干扰抑制算法,在空域和极化联合域实现了电离层杂波的多域协同抑制。此外,还进一步提出了多波束合成算法,在保持杂波抑制效果的同时扩大了观测目标的角度范围,以保持与传统雷达相近的处理效果。理论分析和实测数据处理结果表明:利用本文提出的基于斜投影的空域和极化域滤波算法,电离层杂波可得到较好的抑制;而多域协同处理可在此基础上,实现更好的杂波抑制效果。论文验证了多域协同处理的优势和可行性,为下一代高频地波雷达抗干扰提供了一种有价值的解决方案,也为后续基于极化敏感阵列的抗干扰研究提供了启发和思路。
[Abstract]:Because of the complicated electromagnetic environment in short wave band, high frequency ground wave radar is vulnerable to shortwave radio, effects of ionospheric clutter and other types of radio frequency interference. The ionospheric clutter is the biggest factor currently limiting HF radar survivability. The traditional method is mainly used in high frequency ground wave radar anti ionospheric clutter in time domain, spatial domain and partial information polarization domain to suppress clutter, because did not make full use of all the information of targets and clutter, anti-jamming effect is limited, the scope also has its limitations. The comprehensive utilization of spatial and polarization signal processing technology, multi domain collaborative jamming is an effective means to solve these problems. This paper is based on the spatial signal processing and polarization domain signal processing, the oblique projection as a mathematical tool for interference suppression method, dig the spatial and polarization domain filtering potential Force. On this basis, further study the time-frequency domain, spatial and polarization domain signal processing based on multi domain collaborative ionospheric clutter suppression system and method. The main research contents are as follows: 1, a large number of measured data based on long term observation in the second chapter, analysis of the ionospheric clutter in time domain and Doppler domain. Polarization domain and spatial characteristics of ionospheric clutter time non-stationary. Then based on a brief introduction of the oblique projection operator, the basic framework of collaborative anti-interference methods outlined in multi domain, for the subsequent anti interference method research.2 lay the foundation, the third chapter studied the interference suppression method in airspace. Interference suppression is the main means to suppress the RF interference in HF radar using spatial filtering, but there are also a series of problems. The first is how to design the optimal filter, while maintaining the target letter The number of coherent characteristics at the same time achieve optimal interference suppression; secondly, how to realize multi interference under the condition of suppression is a problem to be solved; in addition, taking into account the limited array aperture in HF radar practical system, often leads to conventional spatial filter to form a sufficiently narrow mainlobe notch or airspace, the ionospheric clutter and target when the range is close, the filtered SNR improvement is not ideal. In order to solve the above problems, this chapter begins with the oblique projection filter based on single interference suppression is proposed to improve SINR quasi optimal spatial filter is based on the oblique projection. The oblique projection filter can ensure the target without distortion by, at the same time the interference range form the airspace null suppression. To suppress the interference to the greatest extent while maintaining coherent characteristics of target signal. In particular, the inhibition ability of Located in the main lobe interference in the main beam and equally effective, with inhibition of mainlobe interference. The oblique projection filter in spatial noise gain larger space is small the protagonist, improved oblique projection filter SINR optimal criterion based on the improved SINR performance in low SNR conditions under projection spatial filtering for multiple interference suppression, interference suppression algorithm is proposed in this paper. The oblique projection of spatial filter, according to multiple directions exist at the same time ionospheric clutter, in the range Doppler domain interference suppression. The method by constructing multiple parallel oblique projection in spatial filter, interference range respectively form corresponding null space in order to inhibit multiple ionospheric clutter. On this basis, in the range Doppler domain logic operation, which will all interference and suppressed. Furthermore, this chapter puts forward A mainlobe range Doppler domain interference suppression spatial filtering algorithm, for solving the interference range can not be accurately estimated when the interference suppression problem. The algorithm is based on the interference suppression algorithm in hand, increase the number of notches in non airspace, and expect to cover more features; on the other hand the use of a single oblique projection the spatial filter can suppress mainlobe interference, some of the notch is arranged on the main valve in the realization of the main lobe interference suppression.3, interference suppression method in polarization domain in the fourth chapter. Based on the oblique projection polarization filter due to orthogonality without full polaron space, has great potential in suppressing interference polarization. But at present, the oblique projection polarization filter in time domain and frequency domain. This paper will further expand to range Doppler domain and range time domain. First of all, the range Doppler domain electric separation Clutter suppression algorithm for low power ionospheric clutter, clutter in range Doppler domain set sample window polarization estimation and clutter suppression; secondly, the distance of time domain ionospheric clutter suppression algorithm for energy and nonstationarity of ionospheric clutter in the range time domain grouping and polarization estimation suppression. Finally, on the basis of the two algorithms proposed ionospheric clutter suppression scheme in polarization domain can effectively inhibit.4 of non-stationary ionospheric clutter, study on the coordination of multi domain interference suppression method in the fifth chapter, the oblique projection polarization domain collaborative filtering algorithm and the high frequency interference suppression surface wave radar ionospheric clutter was suppressed. The oblique projection polarization filtering and spatial filtering have their own characteristics, but when the target and the clutter range coincide or polarization state is close to the two The performance of filters will become worse. In order to solve this problem, and obtain the signal spatial and polarization domain information using polarization sensitive array in this paper, and based on the construction of multi domain collaborative system model. This paper firstly discusses the advantages and characteristics of the filter with oblique projection polarization sensitive array based on multi domain association; secondly, study the equivalent estimation method of polarization sensitive array parameters; thirdly, study the relationship between the polarization of the auxiliary channel with high frequency ground wave radar antenna array with polarization sensitive array; finally, combined with the oblique projection polarization filtering range Doppler domain and oblique projection spatial filtering algorithm, the oblique projection polarization domain coordination the filtering algorithm of interference suppression, the spatial and polarization domain to realize multi domain ionospheric clutter suppression coordination. In addition, further puts forward the multi beam synthesis algorithm, while maintaining the Clutter suppression effect at the same time to expand the target range, in order to maintain the treatment effect with the traditional radar similar. Theoretical analysis and experimental results show that the proposed spatial and polarization domain filtering algorithm based on oblique projection, to better Bokede ionospheric clutter suppression; and multi domain collaboration processing based on the clutter suppression effect to achieve better. The paper shows the advantage and feasibility of multi domain collaborative processing, provides a valuable solution for the next generation of HF radar anti-jamming, but also for the subsequent research on anti jamming based on polarization sensitive array provides inspiration and ideas.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN958

【参考文献】