基于罗兰C系统的无源探测可行性研究

发布时间：2018-02-21 14:29

本文关键词： 罗兰C系统无源探测匹配滤波实测数据 GUI软件　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：本文围绕了利用罗兰C系统进行无源探测的可行性展开了课题的相关研究工作,主要目的是为了验证罗兰C系统是否能够进行无源探测,并基于此目的分别对罗兰C系统在理论上和实际上的无源探测可行性做了一定的探究。本文所做的具体工作如下:1.介绍了罗兰C系统的双曲线定位原理、发射信号、罗兰C台链的构成原则以及详细的阐述了各个台链奇偶周期的脉冲编码及作用。并分析了罗兰C系统工作时遇到的干扰信号类型,总结了抑制这些干扰的方法和这些抑制方法的优缺点。最后介绍了罗兰C系统在周期识别时亟待需要解决的天地波时延估计的问题,通过对天地波时延估计的重要性介绍,进而引入了求解天地波时延的一些算法,并总结了算法的特点。2.从无源探测系统的理论要求出发,进行了大量的定量理论分析和仿真实验,主要从罗兰C信号的匹配滤波系数的选择、罗兰C信号的距离和速度的分辨率、罗兰C信号的相位一致性等方面做了相关工作。通过仿真得知,仿真产生的匹配滤波系数与实际发射信号作为匹配滤波系数差别较大,虽然发射信号有拖尾现象,但是在匹配滤波时,还是要根据实际情况将从发射站耦合的信号作为匹配滤波系数,这样才能保证滤波时不会处于失配状态。罗兰C信号的距离分辨率很差,此时考虑借助多普勒信息上区分目标,即从距离和多普勒两维联合的角度进行目标的探测。要利用罗兰C信号多普勒特性进行目标的探测,需要较长时间相干积累,这就要考虑罗兰C信号长时间相干积累的距离走动问题。崇左台发射信号和蒲城发射信号的相位一致性较好,但通过各自发射信号的对比可以看出,崇左台发射信号的相位一致性比蒲城发射信号好,再通过与理论仿真信号对比时发现,崇左台发射信号的尾部保相特性没有蒲城台发射信号保相特性好。3.展开了利用了罗兰C信号对海面上目标的探测的可行性实验,采集实测数据,并分析和处理了实测数据,针对实测数据处理中的若干问题,研究了相应的解决方案。如采集回波信号包络和相位走动,通过分析判断得出问题的原因是采样时钟信号与发射信号时钟不同步,存在偏差从而导致包络和相位走动。采用了对回波信号谱分析的方法,求出频率偏差。进而将包络和相位的走动补偿。利用直达波直接置零的方法处理了实测数据,处理的结果杂乱且不能关联。后来又利用了罗兰C系统的奇偶脉冲组的相位编码是互补码特性,对实测数据进行了脉冲组匹配滤波的处理,处理的结果同样不能令人满意。最后,为了便于直观、有效和快速的处理和分析罗兰C实测数据,设计和开发了一款基于MATLAB GUI技术的罗兰C系统无源探测实测数据处理软件,该软件主要利用前面介绍的信号处理方法进行信号处理,通过实际的使用、测试和验证,该软件都能够稳定、有效、快速的完成实测数据处理的任务。
[Abstract]:This paper focuses on the feasibility of passive detection using Loran C system. The main purpose of this paper is to verify whether the Loran C system can be used for passive detection. Based on this purpose, the feasibility of passive detection of Loran C system in theory and in practice is explored. The specific work of this paper is as follows: 1. The hyperbolic positioning principle of Roland C system and the transmitting signal are introduced. The composing principle of Loran C chain and the pulse coding and function of the odd and even periods of each station chain are described in detail. The types of interference signals encountered in the operation of Loran C system are analyzed. In this paper, the methods to suppress these disturbances and their advantages and disadvantages are summarized. Finally, the problems of time delay estimation of ground and earth waves which need to be solved urgently in Loran-C system are introduced, and the importance of time delay estimation of space and earth waves is introduced. Furthermore, some algorithms to solve the time-delay of space-time wave are introduced, and the characteristics of the algorithm are summarized. 2. According to the theoretical requirements of passive detection system, a large number of quantitative theoretical analysis and simulation experiments are carried out. This paper mainly deals with the selection of matching filtering coefficient of Loran-C signal, the resolution of range and velocity of Loran-C signal, the phase consistency of Loran-C signal, and so on. The simulation results show that the matching filter coefficient is different from the actual transmitted signal as the matching filter coefficient. Although the transmitted signal has the phenomenon of trailing, but in the case of matched filtering, According to the actual situation, the signal coupled from the transmitting station should be taken as the matched filter coefficient, so as to ensure that the filter will not be mismatched. The range resolution of the Loran C signal is very poor. That is to say, target detection is carried out from the angle of the combination of range and Doppler. In order to use the Doppler characteristic of Loran C signal to detect the target, it takes a long time coherent accumulation to detect the target. It is necessary to consider the problem of long time coherent accumulation of Loran-C signal. The phase consistency between Chongzuo station's transmitting signal and Pucheng's is good, but it can be seen from the comparison of their respective transmitting signals. The phase consistency of the emission signal of Chongzuo station is better than that of Pucheng, and when compared with the theoretical simulation signal, it is found that, The tail phase preserving characteristic of the emission signal of Chongzuo station is not as good as that of Pucheng station. 3. The feasibility experiment of detecting the target on the sea surface by using the Loran C signal is carried out, and the measured data are collected, and the measured data are analyzed and processed. In view of some problems in the processing of the measured data, the corresponding solutions are studied, such as the envelope and phase walk of the collected echo signal, and the reason of the problem is that the sampling clock signal and the transmitting signal clock are out of sync. The error leads to envelope and phase walk. The frequency deviation is calculated by analyzing the echo signal spectrum, and then the envelope and phase walk are compensated. The method of direct zero setting is used to deal with the measured data. The results of processing are chaotic and can not be correlated. The phase coding of even and odd pulse group of Roland C system is used as complementary code, and the real data is processed by pulse group matched filtering. Finally, in order to process and analyze the measured data of Roland C directly, effectively and quickly, a passive detection data processing software of Loran-C system based on MATLAB GUI technology is designed and developed. The software mainly uses the signal processing method introduced before to process the signal. Through practical use, testing and verification, the software can be stable, effective and fast to complete the task of data processing.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN96

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