矢量跟踪条件下的Compass信号监测与评估技术研究

Vector tracking mode has been the research hot spot of signal processing algorithm on navigation user terminal.Vector loop has large scale application on the many fields of GPS, but the deeper research on the performance evaluation has not been done especially for the stability.Aimed at the need of Compass signal monitoring and evaluation,the project will focus on the observation extraction and quality evaluation with the fusion of multi-sources vector information.The signal monitoring level will be improved by performance priority of vectro loop. Firstly, the classical limit on data fusion levels will be broken through, whereas a robust and practial frame combining tight and deep coupling will be established.For the characteristic of Compass system, the signal quality evalution frame based on not only the traditional CNR (Carrier to noise ratio) but also a new complete and systemic criteria will be proposed.On the basis, the merit and defection of vector performance will be analysed and validated by the theory of loop response and steady error. Next,taking the multipath characteristics caused by hybrid Compass constellation and the special needs of the integration into account, the impacts of multipath on Doppler measurements will be quantitatively analyzed. Finally, the integrity algorithm for the vector tracking architecture will be designed to solve the problem of error spread in vector data fusion. The study provides new methods for the system monitoring and signal quality evaluation using Compass/INS vector data fusion.

矢量跟踪已成为导航终端信号处理算法的研究热点。矢量环在GPS领域的应用实例很多，但深层次性能评估尤其是稳定性却鲜有研究。本项目立足于COMPASS特殊性和信号监测评估的需要，研究多源矢量信息条件下的COMPASS观测量提取和信号质量评估，拟利用矢量环的性能优势提高信号监测水平。 拟首先突破经典的数据融合层次界限，建立一个新颖而可靠实用的深层次数据融合框架；针对COMPASS系统的特点，改变单一的信号强度评价方法，建立一个全面系统的信号质量评价准则；在此基础上，从环路响应、稳态误差等理论层面解释矢量环的优劣性并加以验证。针对COMPASS混合星座引起的多径现象和COMPASS/INS组合的特殊需求，定量分析多径对Doppler测量的影响；最后针对误差在矢量融合过程中易扩散的问题，设计矢量跟踪结构下的完好性检测算法；通过矢量融合的方式为复杂环境下COMPASS系统监测与信号质量评估提供新方法。

北斗二号系统作为我国自行研制的第一代无源卫星导航系统，已经在国民经济中发挥重大作用。矢量跟踪方法由于优越的处理性能，自然可以应用在北斗系统的用户端系统建设之中，既可以弥补卫导系统的自身不足，又能提高信号监测的水平，由此促成了本项目的立项。.项目首先分析了矢量跟踪性能提升的实质性问题，即通过多通道的伪距和多普勒观测量进行信息融合，降低观测值的误差，从而提高反馈的精度。从性能分析的角度看，无论是标量的单通道环路或矢量的多通道环路，都受到弱信号和动态性的联合制约，这样就可以简化矢量分析的复杂度。即由于精度的提升，扩大制约门限的容忍范围。在建立简明矢量结构的基础上，建立观测域、信号域、信息域的三层次信号质量联合评价体系。三者间的关系既有联系，又相互补充。针对北斗系统特有的多径和Doppler测量精度问题，从形成机理和误差要素影响等方面进行综合分析，并设计出利用矢量跟踪的性能优势优化Doppler测算精度的方法。最后，针对误差传播的问题，分为信号类和信息类进行处理，信号类错误利用码相关模型分析输出幅值概率密度分布函数的特点，即通过锁定检测器来判断信号质量的好坏，从而避免伪距层面的信息来源无法确定的问题，信息类错误通过系统级的故障树模型按照融合原则进行优化处理。