射电天线抗导航频率干扰技术研究

发布时间：2018-06-20 21:43

本文选题：射电天线 + 评价指标　；参考：《国防科学技术大学》2015年硕士论文

【摘要】：自二十世纪30年代以来,随着射电天文望远镜分辨率的不断提高,射电天文事业的观测频率范围已扩展到1MHz-1000GHz。然而无线电事业也日益壮大,对无线电频谱的需求也越来越大,影响了射电天文的观测,阻碍了射电天文事业的发展。事实表明射电天文观测受到的干扰越来越多都是来自地面的,其中数全球卫星导航信号最为常见。本文基于利用射电天线观测21cm谱线时容易受到GPS L2信号干扰这个研究背景,采用单辅助天线方法,针对以下两个射电天线抗干扰中常见的问题进行了研究:现有评价指标对抗干扰性能评价方面的局限和主辅天线接收导航信号时存在的分数时延差会影响抗干扰方法的性能。针对评价指标的局限性,文中结合抗干扰中几种常用评价指标,通过理论推导出了两个评价指标:信号衰减度Gs和干扰抑制度GI,简单直接的分别对抗干扰后信号中射电天文信号和导航干扰功率上的变化量做出了统计,准确地评价了抗干扰算法性能。针对主辅天线中导航干扰存在时延差的问题,采用了最优化方法和AP窗方法,对分数时延固定的情况设计了两种精度较高的分数时延FIR滤波器,时延误差高达10-7量级。最后提出了基于时延匹配的自适应滤波方法,通过计算机仿真,探索并比较了LMS类算法和基于时延匹配的LMS类算法性能的同时,证明了后者在一定程度上提高了LMS类算法的抗干扰性能,还验证了提出评价指标的有效性。
[Abstract]:Since the 1930s, with the increasing resolution of radio telescopes, the observational frequency range of radio astronomy has been extended to 1MHz-1000GHz. However, the radio industry is growing stronger and the demand for radio spectrum is increasing, which affects the observation of radio astronomy and hinders the development of radio astronomy. The facts show that more and more interference of radio astronomical observation is from the ground, among which, several global satellite navigation signals are the most common. Based on the research background that the radio antenna is easy to be disturbed by 21cm L2 signal, a single auxiliary antenna method is used in this paper. The following two common problems in radio antenna anti-jamming are studied: the limitation of existing evaluation indexes on anti-jamming performance and the difference in fractional delay between main and auxiliary antennas in receiving navigation signals will affect the performance of anti-jamming methods. Aiming at the limitation of evaluation index, this paper combines several commonly used evaluation indexes in anti-jamming. Through the theoretical derivation of two evaluation indexes: signal attenuation (Gs) and interference suppression (Gi), the variations of radio astronomical signal and navigation interference power in the anti-jamming signal are simply and directly analyzed. The performance of anti-jamming algorithm is evaluated accurately. Aiming at the problem of delay difference in navigation interference between main and auxiliary antennas, the optimization method and AP window method are used to design two kinds of fractional delay Fir filters with high precision when fractional delay is fixed. The delay error is as high as 10-7 order of magnitude. Finally, an adaptive filtering method based on delay matching is proposed. By computer simulation, the performance of LMS class algorithm and delay matching based LMS class algorithm are explored and compared. It is proved that the latter improves the anti-jamming performance of LMS class algorithm to some extent, and the validity of the proposed evaluation index is also verified.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P111.44;TN967.1

【参考文献】