I 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西安电子科技大学硕士学位报告 II 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。 关 键 词，罗兰 C 系统，无源探测，匹配滤波，实测数据，GUI 软件 报告类型，应用基础研究类ABSTRACT III ABSTRACT This paper revolves around the feasibility of passive detection through the using of Loran-C system, as the subject relevant research work, the main purpose is to verify whether the Loran-C system can be passive detection or not, and based on the Loran-C system for this purpose in theory and practical respectively passive detection done on the feasibility of certain exploration. Specific work as follows: 1. Introduce Loran-C system, mainly include the principle of hyperbolic positioning, transmitted signal, Loran-C station chains constituting principles and detailed exposi- tion of the pulse-code each station chain parity cycle and their roles. Analyzes the types of Loran-C system interference signals encountered at work, summed up various interference suppression methods and the advantages and disadvantages of these interference suppression methods. Finally, a problem that in the cycle identification of Loran-C signal, groundwave and skywave latency estimation should be solved urgently have been introduced. Through the introduction of the importance of the skywave latency estimation, and then introduces a number of algorithms for solving skywave latency. At last, summarize the characteristics of these algorithms. 2. From the theory requirements of passive detection system as the beginning, do the large amount of quantitative analysis and simulation experiments, from the choice of the matched filter coefficients to Loran-C signal, the resolution of distance and speed for the Loran-C signal, and nalysis the phase congruency of Loran-C signal and do other aspects the relevant work. From these simulations we can get a lot of information, there are great differences between the matched filter coefficients and the actual transmission signal generated by the simulation, as the matched filter coefficients, although the launch signal has a tailing phenomenon, but when the matching filter, also need to be coupled to the signal from the transmitting station as a matched filter coefficients according to the actual situation factor, so as to ensure that not in mismatched filtering state. The range resolution of Loran-C signal is bad, consider using the doppler informa- tion to distinguish the targets, that is, from the union of two-dimensional of the distance and doppler to detect targets. If we want to make use of Loran-C signal doppler characteristics to target detection, we need takes longer coherent integration, it is need to consider the problem of Loran-C signal long coherent accumulation. For phase西安电子科技大学硕士学位报告 IV congruency, Pucheng station transmitting signals is better than Chongzuo station transmitting signals, but through the contrast of theirself emission signals can be seen that the phase coherence Chongzuo station transmits signals emitted signal is better than Pucheng, and with the theoreticcal the simulation signal comparison, the phase behavior of the tail in Chongzuo station transmit signal is not good Pucheng station transmits in the signal phase preserving characteristics. 3. Explore the Loran-C signal on the feasibility of detect- ing surface targets, primarily process and analysis the measured signal. Processing the measured signal is also fall across a considerable number of issues, when encountered in the acquisition of the echo signal envelope and phase of walking problems, find out that the sampling clock signal with the transmitted signal clocks are not synchronized, last resulting in a frequency offset. Analysis the spectral from the slow time to the echo signal, to obtain a frequency deviation. Then compensate the frequency offset, and have a good effects. Directly use the method of direct wave is set to zero signal processing methods for processing the measured signal, processing result is not good. With the phase-coded pulse groups parity Loran-C system are complementary code feature, the measured data were matched filter processing of pulses, the results of the processing of unsatisfactory. Finally, in order to facilitate intuitive, effective and fast processing and analysis Loran-C measured data, to design and develop a software that based on MATLAB GUI technology to process measured data which is based on Loran-C system passive detection, mainly use the preceding article of the signal processing algorithms, according to the actual using, testing and verification, the software can be stable and effective, rapid completion of the target of process measured data. Keywords: Loran-C System，Passive Detection，Matched Filtering，Measured Data，GUI Software Type of Dissertation:Applied Basic Research插图索引 V 插图索引 图 2.1 罗兰 C 系统导航原理示意图..............................................................................7 图 2.2 罗兰 C 信号时域波形及其包络..........................................................................8 图 2.3 标准罗兰 C 信号发生畸形时的时域波形及包络..............................................9 图 2.4 罗兰 C 系统导航台链模型..................................................................................9 图 2.5 脉冲组模型.........................................................................................................10 图 2.6 脉冲组实际发射信号.........................................................................................10 图 2.7 台链脉冲组发射模型.........................................................................................11 图 2.8 地波跟踪点示意图.............................................................................................11 图 2.9 编码后的奇偶周期发射信号..............