卫星重力测量中的星间精密测距关键技术研究

发布时间：2018-05-07 01:37

本文选题：地球重力测量 + 星间精密测距　；参考：《国防科学技术大学》2013年博士论文

【摘要】：通过测量同轨道面上两颗近距离低轨卫星之间的微小距离变化,可以精确反演出地球重力场。为实现地球重力场的高精度测量,星间测距的精度需求为微米量级。星间精密测距的基本测量方法是双向单程测距(Dual One-Way Ranging,DOWR)方法,它的一个制约性基础条件是要求双星对测量信号的采样时刻之间保持同步。由于双星的时钟不同源,星间时标不能完全同步,会导致测距误差。由此产生了本文研究的基本问题——如何降低星间精密测距中与时标有关的测距误差,为此,论文重点研究了以下四个关键技术问题:1.测距误差模型问题。星间精密测距中涉及的误差源非常复杂,部分误差源之间还存在相互耦合的关系。要有效降低星间测距误差,必须给出一个定量描述误差与其影响要素之间的函数关系——测距误差模型。因此,如何确定测距误差模型成为星间精密测距的关键问题。2.双星时标统一问题。全球重力场测量需要高度的时空统一,星间精密测距需要两星时标精确同步,重力测量结果的地球坐标赋值需要空间位置同步,二者统一归结为将卫星时标统一到某个参考时间系统。在得不到GPS P(Y)码的支持,且我国的北斗区域导航系统目前仅能提供局域溯源的条件下,要自主实现双星时标的统一成为瓶颈难题。3.时标偏差修正问题。卫星重力测量中的星间精密测距,需要的是地球经纬度坐标上的距离测量值,根据卫星轨道,对应于参考时间系统中某一时刻nt上的量值。由于存在时标偏差n?,卫星的测量数据是时刻n nt??上的量值。必须对测量数据中的时标偏差进行有效修正,才能得到精密的星间距离。因此,时标偏差修正问题是星间精密测距的关键问题。4.测距信号优化设计问题。星间精密测距的误差与测距信号的结构参数有直接的关系。在测距信号的结构组成中,频率设计值容许一定的选择范围。对于采用双频测距信号的星间精密测距而言,通过优化设置测距信号的频点可以进一步降低测距误差,有必要研究最佳的频率组合以及实现最佳频率的方法。因此,测距信号的优化设计是星间精密测距的关键问题。为解决上述关键技术问题,论文建立了双星时标统一的非相对论测距误差模型,提出了一种基于双向时间传递和北斗时局域溯源的时标统一方法,提出了一种基于插值拟合的时标偏差分步修正方法,提出了一种DOWR信号的频率优化组合方法。这些技术方法作为上述四个关键技术问题的解决方案,均通过理论分析和仿真验证了其有效性,并在测距系统中得到了实现,通过实验验证了其技术可行性。
[Abstract]:By measuring the small distance variation between two low-orbit satellites in the same orbit, the Earth's gravity field can be accurately reversed. In order to realize the high precision measurement of the earth gravity field, the precision of the ranging between satellites is of the order of micron. The basic measurement method of intersatellite precision ranging is the dual One-Way ranging DOWR method. One of its restrictive conditions is that the sampling time of the measured signal is required to be synchronized between the two satellites. Because the binary clock is not homologous, the time scale can not be fully synchronized, which will lead to ranging error. Therefore, the basic problem of this paper is how to reduce the ranging error related to time scale in the intersatellite precision ranging. For this reason, this paper focuses on the following four key technical problems: 1. The problem of ranging error model. The error sources involved in the intersatellite precision ranging are very complex, and some of the error sources are coupled with each other. In order to effectively reduce the ranging error between satellites, a functional relationship between the quantitative description error and its influencing factors must be given, that is, the ranging error model. Therefore, how to determine the ranging error model has become the key problem of intersatellite precision ranging. The unification of double star time scale. The global gravity field measurement needs high spatial and temporal unity, the precise ranging between satellites needs the precise synchronization of two satellite time scales, and the earth coordinate assignment of gravity measurement results needs space position synchronization. The unification of the two comes down to the unification of the satellite time scale into a reference time system. Without the support of GPS Pian YC code and the fact that the Beidou regional navigation system in China can only provide local traceability at present, it is a bottleneck problem to realize the unification of dual star time scale independently. Correction of time scale deviation. In the satellite gravimetry, the distance measurement value in the coordinates of longitude and latitude of the earth is required. According to the satellite orbit, it corresponds to the value of NT at a certain time in the reference time system. Due to the existence of time scale deviation, the measured data of the satellite is the time n NT? The amount of value on. The time scale deviation in the measured data must be corrected effectively in order to obtain the precise inter-satellite distance. Therefore, the correction of time scale deviation is the key problem of intersatellite precision ranging. Optimal design of ranging signal. The error of intersatellite precision ranging is directly related to the structural parameters of ranging signal. In the structure composition of ranging signal, the frequency design value allows a certain range of selection. For the intersatellite precision ranging with dual-frequency ranging signal, the ranging error can be further reduced by optimizing the frequency point of ranging signal. It is necessary to study the best frequency combination and the method of realizing the best frequency. Therefore, the optimal design of ranging signal is the key problem of inter-satellite precision ranging. In order to solve the above key technical problems, a unified non-relativistic ranging error model of double star time scale is established, and a unified method based on bidirectional time transfer and local traceability of Beidou time scale is proposed. In this paper, a time scale deviation step correction method based on interpolation fitting is proposed, and a frequency optimal combination method of DOWR signal is proposed. As the solutions of the four key technical problems mentioned above, these technical methods are proved to be effective by theoretical analysis and simulation, and implemented in the ranging system. The technical feasibility is verified by experiments.
【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：P223.4

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