【作者】 吴海涛；

【导师】 李志刚； 边玉敬；

【作者基本信息】 中国科学院研究生院（国家授时中心） ， 天体测量与天体力学， 2002， 博士

【摘要】 本论文的主要研究目的是提高和改进罗兰C授时能力。虽然GPS被广泛应用，但在欧洲、亚洲，甚至美国，罗兰C作为国家基础设施的重要组成部分，在授时方面依然被高度期望成为可选的主用定时参考源。由于罗兰C信号缺乏足够的信息标识参考脉冲，罗兰C还不能独立授时。本文通过研究认为，在罗兰C信道上增加合适的时间信息(第一篇的研究内容)或利用多链罗兰C信息(第二篇的研究内容)，能够完善罗兰C高精度授时的自主性，提高定时信号的精确度和用户定时的自动化水平，从而提升该系统的可利用度和可接受程度。作者所做工作及主要成果如下： 本论文在国际上首次提出并详细研究了两种解决途径。第一条途径是对罗兰C信号进行附加调制，利用增加的时间信息完善授时功能，这是本论文的重点和主体。第二条途径是根据不同罗兰C链的TOC的重合规律，研究利用多链罗兰C信号实现自主TOC同步。 介绍了在现有罗兰C信号上增加其它附加信息调制的基本思想和国外的实验结果。在此基础上，我们提出了具有普适意义的PPM方法，研究了PPM的有关性能，给出了我国罗兰C台的有关参数。我们的实验结果也表明，PPM是可行的。 研究了罗兰C自主实现TOC同步的原理。根据TOC的特点，分析了罗兰C自主TOC同步的基本要求，然后根据广播TOC信息的目的，定义了TOC信息的概念。我们提出并定义了与ITU-R建议M589．3兼容的新的信息类型-TOC信息类型，并制订了相应的通信规约。分析了GRI脉冲序列与参考脉冲，以及调制码组与罗兰C脉冲组的时间关系。研究了在突发传输(TOC信息)和连续传输(TOC信息和DGPS交替)方式下，TOC同步的原理和方法。 研究了TOC信息的数据编码格式和帧结构。讨论了各种可能的数据信息的结构，并给出了有关参数和数据的计算方法和公式。发播内容的选择是由期望的系统功能决定的，广播内容的编排则与具体实现技术相关。给出了信息帧比特安排、时码格式、帧结构的详细结果。TOC信息主要包括UTC时码、发射信号相对于标准时间的改正数、跳秒信息和用于自动标识参考脉冲的TOC距离数据。 研究了广播TOC信息的控制算法和方法。TOC信息的发播与一般数据的广播(如播发DGNSS信息)有些不同，它除了发布相关数据信息外，还必须提供准时标志。这就需要精确的发射控制，以便TOC信息能与参考脉冲相对应并标识参考脉冲。在罗兰C数据信道上，TOC信息能够单一或与DGNSS数据交替广播，分析了在交替广播方式 罗兰C自主授时及其数据通信的研究下的原信息的可用性。椎导了获得TOC信息帧帧头位置序号的递推算法，提出了相应的控制方法。信息帧发射控制和帧同步是实现自主TOC同步的关键。 研究了TOC信息的接收方法。讨论了PPM调制信号的相干解调方法，得到了相关检测的判决表达式、判决域和相应的相关检测器，提出了一种得到本地参考信号的方法。提出了利用TOC信息实现高精度或低精度定时的方法，当然电路的复杂性也会有所不同，但均可得到TOC时码或全信息连续时间编码输出。 通过分析多链罗兰C信号的特点，提出了利用多链罗兰C信号实现UTC同步的方法。首次提出了多链罗兰C信号的有关定义和性质，研究了用户利用多链信号实现UTC同步的基本原理，给出了多链TOC秒重合和不重合两种情况下的实现方法。采用这些方法，用户也可以摆脱对粗同步手段的依赖，提高定时的自动化水平。更多还原

【Abstract】 Improving and ameliorating the ability of Loran-C for time service are the main objective of our study in this paper. Although GPS has been widely used , Loran-C is still highly desirable to be as an alternative PRS(primary timing reference source) for an important part of a nation’s infrastructure in Europe ,Asia, and others areas, even in United States. The current standard Loran-C signals lack of enough information to mark the precision reference pulses, Loran-C couldn’t be considered as an independent system in precision timing applications. The paper will show that, if appropriate time information are added into the signals over the Loran-C data channel(studied in the first part of the paper) or in which the current multi-chains signals can be skillfully dealt with(studied in the second part of the paper), the independence of Loran-C for precision timing can be perfected, as well as the precision of timing signals and the automatization level of UTC synchronization can be improved , thereby the Loran-C can be acceptant and employed widely.Two approaches are advanced in the first time and studied in detail in this paper. The first approach , which is the emphases and main body of this dissertation, is additional PPM(Pulse Position Modulation) through which new time message will be modulated onto the Loran-C pulses signal. Using the Multi-chains Loran-C signals to implement the independent UTC synchronization is the second approach, which is relied on the Coincidence Rule among TOCs of different Loran-C chains.In this paper, the basic concept of PPM and experiment results are introduced. On the basis of these achievement, we put forward a general method of PPM. The performance of PPM in influencing normal Loran-C operation, raw data rate ,as well as possibility of error are analyzed, too. Results are also given to the Loran-C systems in China according to their charateristic parameters. Our test results show that the PPM is feasible.The principle of independent TOC(Time of Coincidence) synchronization over Loran-C data channel is studied . The essential requirement of TOC synchronization is analyzed according to the characteristic of TOC. The concept of TOC Message is defined. In this paper, we put forward and define a new message type-TOC message type, which is coincident with the latest ITU-R recommendation M589.3. The corresponding communication protocol is presented. The relationships between GRI pulse sequences and reference pulses, as well as between modulation code groups and Loran-C pulse groups are analyzed. Finally, as examples, the method of independent TOC synchronization are studied for the mode of burst transmission and continuous transmission.The formats of data coding and frame structures are studied. The structure of all possible data information is discussed, as well as the calculation methods and equations for some important parameters and data are given. The selection of data for broadcasting depends on the expected time service function of Loran-C, and the data layout is related to the adopted technique. The details of the message bit assignment and time code format and frame structures are given. The TOC message will obtain UTC time code, the corrections of the time of emission UTC(Transmitting Clock)-UTC(k), leap seconds, as well as the TOC(Time of Coincidence) distance data which is used to locate the TOC automatically.The algorithms and approach for TOC message broadcasting control are studied in this paper. The function of TOC message we suggest here is so distinctly different with the current DGNSS message be broadcasting in NELS that a precision transmission control of the UTC message is needed, in order that the information and data in the message could be consistent with the reference pulse and denote the pulse. The TOC message can be broadcasted, solely or alternating with DGNSS message, over one Loran-C data channel. The availability of the messages in alternating broadcast mode is analyzed. The recurrence formulae of the sequence number of the header of the TOC更多还原