基于混叠信号可分离机理的GNSS抗干扰技术研究

发布时间：2018-11-22 11:09

【摘要】：全球导航卫星系统已经逐步发展成为具有全球性、实时性和全天候的高精度导航系统,在军事和民用领域获得了广泛应用。由于GNSS信号很容易受到有意或无意的干扰,用户接收机的抗干扰能力已成为导航系统正常工作的关键问题。空域抗干扰技术对天线指向和各个信号的来波方向等信号的先验信息都有较高的要求,使得空域抗干扰技术存在很大的局限性。针对这个问题,本文在未知GNSS信号的先验信息及传输通道的情况下,通过盲源分离技术将GNSS信号和干扰信号分离实现抗干扰。本文主要研究内容如下:1.根据GNSS信号和干扰信号的特点,研究了GNSS信号自抗能力及干扰信号对GNSS信号的影响。仿真表明,干扰信号对GNSS信号捕获影响非常大,消除干扰信号对GNSS信号捕获影响具有重要意义。2.针对传统定点分离算法对初始矩阵值敏感问题,通过引入下降因子改进了传统定点分离算法。仿真结果表明,本文分离算法迭代过程更平滑稳定,分离后的GNSS信号更接近原GNSS信号,说明分离算法能将GNSS信号与干扰信号分离实现抗干扰。3.目前分离算法都是针对无噪信号分离过程,但是GNSS信号传输的真实环境噪声的影响是不可避免的。文中分析了噪声对分离效果产生的影响,提出了去噪偏差消除分离算法。仿真结果表明,随着信噪比的降低,噪声对分离信号存在严重的影响。通过去噪偏差消除分离算法,分离后的GNSS信号相似度更高,PI值更小,相比传统无噪分离算法,文中分离算法效果明显提高。4.文中详细研究了分离信号的歧义性,研究表明以最小失真法为标准的分离算法能够更好的消除幅度歧义性,通过分离信号进行恢复GNSS信号更接近原GNSS信号。针对传统Murata算法存在的问题,文中提出了相应的改进方法,研究表明本文分离抗干扰算法获得的相似系数更接近1,均方误差更小,说明本文的分离抗干扰算法效果更优。5.借助MATLAB GUI工具,完成了GNSS分离抗干扰软件仿真平台设计,通过仿真验证了本文算法的分离效果和抗干扰性能,为后续相关研究提供可视化软件仿真平台和验证分析方法。
[Abstract]:Global Navigation Satellite system (GNSS) has been gradually developed into a global, real-time and all-weather high-precision navigation system, which has been widely used in military and civilian fields. Because the GNSS signal is vulnerable to intentional or unintentional interference, the anti-jamming ability of the user receiver has become a key problem in the normal operation of the navigation system. The spatial anti-jamming technology has a high requirement for the prior information of the antenna pointing and the direction of the incoming wave of each signal, which makes the anti-jamming technology in the airspace have great limitations. In order to solve this problem, in the case of unknown prior information of GNSS signal and transmission channel, the blind source separation technique is used to separate GNSS signal and interference signal to achieve anti-jamming. The main contents of this paper are as follows: 1. According to the characteristics of GNSS signal and interference signal, the self-reactance of GNSS signal and the influence of interference signal on GNSS signal are studied. Simulation results show that the interference signal has a great influence on GNSS signal acquisition, and it is of great significance to eliminate the interference signal influence on GNSS signal capture. 2. Aiming at the sensitivity of the traditional fixed-point separation algorithm to the initial matrix value, the traditional fixed-point separation algorithm is improved by introducing the descent factor. The simulation results show that the iterative process of the separation algorithm is smoother and stable, and the separated GNSS signal is closer to the original GNSS signal, which indicates that the separation algorithm can separate the GNSS signal from the interference signal to achieve anti-jamming. At present, the separation algorithms are aimed at the noiseless signal separation process, but the impact of the real environment noise of GNSS signal transmission is inevitable. This paper analyzes the effect of noise on the separation effect, and proposes a de-noising deviation elimination separation algorithm. The simulation results show that the noise has a serious effect on the separation signal with the decrease of SNR. By eliminating the noise deviation, the GNSS signal after separation has higher similarity and smaller PI value. Compared with the traditional noise-free separation algorithm, the effect of the separation algorithm in this paper is obviously improved. 4. In this paper, the ambiguity of the separated signal is studied in detail. It is shown that the separation algorithm based on the minimum distortion method can eliminate the ambiguity of amplitude better, and recover the GNSS signal by separating the signal more close to the original GNSS signal. Aiming at the problems of the traditional Murata algorithm, this paper puts forward the corresponding improved method. The research shows that the similarity coefficient and the mean square error obtained by the proposed algorithm are closer to 1 and the mean square error is smaller, which indicates that the effect of the proposed algorithm is better than that of the traditional one. 5. With the help of MATLAB GUI tools, the design of GNSS separation and anti-jamming software simulation platform is completed. The separation effect and anti-interference performance of this algorithm are verified by simulation. The visual software simulation platform and the verification and analysis method are provided for the subsequent related research.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN967.1

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