【作者】 刘宁；

【导师】 熊永良；

【作者基本信息】 西南交通大学 ， 大地测量学与测量工程， 2013， 博士

【摘要】 研究利用地基GPS反演大气水汽不仅对天气变化的预报有重要意义,而且可以促进GPS定位精度的提高,从而发挥GPS在应用方面的潜力。基于此,本文对地基GPS反演大气水汽所涉及的主要问题进行了系统的研究,整个论文的主要研究内容和创新点概括如下：1.概述了影响GPS反演大气水汽各主要问题的研究现状,并指出了本文的研究目标,对GPS的观测模型及估计方法进行了详细的介绍,从而为本文后续数据处理奠定基础。2.分析了广播星历外推卫星轨道的精度,并给出了Lagrange插值、Neville插值、Chebyshev多项式拟合和Legendre多项式拟合进行精密星历加密的方法,通过对实际精密星历数据的计算,分别从内插和拟合的阶数、计算精度、计算效率进行了比较分析,并给出了最佳阶数插值算法和拟合算法计算卫星轨道的点位误差对比图、所有卫星轨道的精度对比效果图。随后,分别以实例对卫星信号发射时刻的两种计算方法与影响卫星轨道的地球自转误差进行了探讨分析。3.基于TurboEdit方法对GPS观测数据进行周跳探测的特点,设计了固定弧段长度的滑动窗口拟合模型,对其中的Geometry-Free组合法进行改进,在探测出周跳后,提出利用最小二乘Chebyshev多项式拟合来修复周跳。实验结果表明：改进后的TurboEdit算法可以探测出等周的1周小周跳、等周的大周跳和连续的小周跳、大周跳,同时,最小二乘Chebyshev多项式拟合可以精确修复以上周跳对。4.根据双差相位观测序列在相邻历元间求差后,周跳能真实地以粗差形式反映出来的特点,在利用Chebyshev多项式拟合双差观测量时,顾及抗差估计的思想、Chebyshev多项式拟合阶数、拟合弧段长度,提出基于移动窗口的抗差Chebyshev多项式拟合算法来探测与修复周跳,应用采样间隔为60s和15s的L1频率的载波相位数据测试表明,该算法可有效的探测多历元间隔周跳及连续周跳,能对周跳进行准确的修复。5.针对不存在先验信息时常规GPS单历元数据处理中存在的问题,提出了一种新的GPS整周模糊度单历元算法。该算法先采用一个历元的码观测值进行最小二乘定位,求取初始模糊度,并根据解的中误差来构造模糊度原始搜索空间。再采用两种不同线性组合的扩波方法进行模糊度变换,使原模糊度的搜索空间变小。在模糊度的新搜索空间确定后,通过线性组合的逆变换求取模糊度N1及N2,并以模糊度函数法进行真值的搜索,实现单历元解算。采用基线长度不同的两组数据作为实例进行测试,试验结果表明了本文方法的可行性和正确性。6.针对单频GPS动态定位中常用模糊度求解方法存在的问题,提出了一种新的整周模糊度快速解算方法。该方法先通过对双差观测方程中坐标参数的系数阵进行QR分解变换以消除坐标参数,从而仅对模糊度参数建立Kalman滤波方程进行估计,然后利用排序和双Cholesky分解对滤波得到的模糊度进行降相关处理,并结合收缩模糊度搜索空间的思想来搜索固定整周模糊度。以实测的动态数据为例对该方法进行测试,其分析结果表明,该方法不但可以改善模糊度浮点解精度,而且具有良好的模糊度降相关效果,可正确有效地实现整周模糊度的快速解算。7.通过考虑模糊度的整数特性及相位波长与基线非参考站初始坐标误差之间的约束条件,提出了一种基于梯级递推的无模糊度基线解算方法。该方法不受周跳的影响,并且在基线求解过程中不用考虑模糊度参数。分别以单个历元和移动窗口的多历元两种求解方案验证了该方法的可行性和正确性,并且基线解算结果具有较高的精度。8.利用参考站坐标已知的先验信息,基于组合后的超快星历,提出了一种参考站对流层湿延迟近实时估计的三步Kalman滤波算法,该方法先利用Kalman滤波分离宽巷模糊度与伪距多路径误差,再基于电离层无关组合模型,启动Kalman滤波器进行L1模糊度与相对对流层湿延迟的分离,然后利用将正确固定的L1双差模糊度进行回代的方法,重新构建Kalman滤波器来估计准确的相对对流层湿延迟参数,通过实例验证了该方法的可行性和正确性。随后,利用该方法获取的近实时对流层湿延迟计算了相应的近实时可降水量,并与GAMIT解算的可降水量结果进行了比较分析。更多还原

【Abstract】 The research on atmospheric water vapor inversion by ground-based GPS not only has important significance for weather forecast, but also can improve the precision of GPS positioning, so as to display potential in the application of GPS. The main problems related to atmospheric water vapor by ground-based GPS inversion were systematically researched in this thesis. The main research contents and innovation points were summarized as follows:1. Research status of the main problems which influence atmospheric water vapor inversion by ground GPS were outlined, and the research goals were pointed out in this thesis, the GPS observation model and estimation method were introduced in detail, so as to lay a foundation for subsequent data processing.2. The broadcast ephemeris extrapolation accuracy of satellite orbit was analyzed,and the methods of Lagrange interpolation, Neville interpolation, Chebyshev and Legendre polynomial fitting applied to precise ephemeris were introduced in this dissertation, through calculation of actual precision ephemeris data, the calculations of precise ephemeris in interpolating and fitting from the order, accuracy and computational efficiency were analysed comparatively, and the best order of the interpolation algorithm and the fitting algorithm of the position error comparison chart and the accuracy of all the satellite figure contrasts were given. And then, two kinds of calculation methods of satellite signal launch time and the earth’s rotation error influencing satellite orbit were respectively analyzed by each numerical example.3. The characteristics of GPS observation data cycle slips detection based on TurboEdit algorithm, fixed length sliding window fitting model has been designed, which makes the improvement to Geometry-Free combination method, using the least square Chebyshev polynomial fitting to repair cycle slips after cycle slips detection is proposed in the dissertation. The experimental results show that the improved TurboEdit algorithm can detect equal-cycle such as one cycle of small cycle slips, big cycle slips and continuing happened small and big cycle slips, at the same time, the least square Chebyshev polynomial fitting can also repair cycle slips more precisely.4. Base on cycle slips act as gross errors after differencing between adjacent epoch in double difference observation sequences, when using Chebyshev polynomial fitting double difference observations, with respect to the thoughts of robust estimation, taking into account of the order of Chebyshev polynomial fitting and the length of fitting arc, cycle slips detection and correction for single-frequency GPS data based on sliding window of robust estimation Chebyshev polynomial fitting was proposed in this dissertation. L1-frequency carrier phase data with sampling interval of60seconds and15seconds were applied for the tests, test results showed that the proposed algorithm can effectively detect multi-epoch cycle slips and continuous cycle slips, and cycle slips can be accurately repaired.5. Aiming at the problem in the conventional GPS single epoch data processing if no priori information, A new algorithm for solving GPS integer ambiguity using single epoch data was proposed in this dissertation. It uses code observation of one epoch to calculate initial ambiguity by least square method, the original search space of ambiguity was constructed by using standard deviation of the initial position, the ambiguity transformation by using two different linear combination of expansion wave was carried out to make the original search space of ambiguity smaller. After the new search space of ambiguity was confirmed, ambiguity N1and N2were solved by means of the inverse linear transformation. Furthermore, ambiguity function method was used for the searching of the true value using single epoch data. Two sets of data for different baseline length was used for analyzing and testing, the experimental results show that the proposed method was feasible and correct.6. Aiming at the problem in the conventional ambiguity algorithm of single frequency GPS kinematical positioning, a new algorithm for rapid integer ambiguity resolution was proposed in this dissertation. In the algorithm, QR decomposition transform of the coordinate coefficient matrix was adopted to eliminate the coordinate parameters in the double difference observation equation, thereby the Kalman Filter equations can be established to estimate only the ambiguity parameters. Then ordering process and double Cholesky decomposition were used for the decorrelation of the filtered ambiguities and the ambiguities were fixed by using the shrinking ambiguity search space strategy. Based on the experimental data for testing the algorithm, the analysis results show that the proposed algorithm can not only improve the accuracy of ambiguity float solution, but also has a good ambiguity decorrelation capability, and it can achieve rapid integer ambiguity resolution correctly and effectively.7. A method of GPS baseline solution based on cascade recursive without ambiguity resolution was proposed in this dissertation, considering the integer characteristic of ambiguity and the constraint condition between wavelength of carrier phase and the initial coordinate error of baseline non-reference station. The method was immune to cycle slip and it is unnecessary to take into account the ambiguity parameters in baseline solution process.The feasibility and correctness of the proposed method were demonstrated by single epoch scheme and multiple-epoch scheme with sliding window model respectively and the baseline resolution results with higher precision can be obtained.8. Using the priori information of known coordinates on reference stations, based on the combination of ultrarapid ephemeris, a three-step kalman filter algorithm for near real-time estimating tropospheric wet delay on reference stations was proposed, in the algorithm, wide lane ambiguity and pseudorange multipath error were separated by using kalman filter, and then, starting the kalman filter for separating L1ambiguity and tropospheric wet delay based on ionosphere-free combination model. After that, using the correctly fixed L1ambiguity back substitution method and rebuilding the kalman filter to estimate accurate relative tropospheric wet delay parameter, the feasibility and correctness of the algorithm was verified through numerical example. Subsequently, using near real-time tropospheric wet delay result obtained by the algorithm to calculate the corresponding near real-time precipitable water vapor, which were compared and analyzed with precipitable water vapor of GAMIT solution.更多还原