【作者】 杨光；

【导师】 华锡生； 何秀凤；

【作者基本信息】 河海大学 ， 水工结构工程， 2004， 博士

【摘要】 传统的变形监测方法在连续性、实时性和自动化程度等方面已越来越难以满足现今大坝、滑坡安全监测的要求。GPS作为当今最先进的测量手段之一，其精密定位理论和技术已在大地测量、地壳运动监测、精密工程测量等诸多领域得到了广泛的应用。GPS应用于变形监测，使得安全监测系统的数据采集、传送、处理和分析的自动化很容易实现，但在三维定位的精度和可靠性以及成本等方面还存在某些缺陷。如受GPS系统本身的一些先天性因素限制，GPS在垂直方向上的定位误差通常为水平方向的2～3倍；并且在水电工程深峡谷遮蔽严重的区域，GPS定位精度会迅速下降，甚至完全无法定位；此外，目前在水下、地下、室内和隧道内还无法采用GPS定位。 伪卫星定位技术是解决这些问题的一条有效途径，采用伪卫星能够增加可用星的数目和改善几何图形结构。本文的研究旨在以GPS和伪卫星的组合来提高定位的精度和可靠性，并实现垂直方向上与水平相当的定位精度，使卫星定位技术能够满足大坝、滑坡安全监测系统的要求。本文的研究内容和结果如下： 1．系统地介绍了伪卫星的概念、伪卫星的导航电文及数据格式、定位原理和伪卫星地面设备，重点研究了远近效应、多路径效应、时间同步等伪卫星定位中的一些关键技术问题。探讨了伪卫星在形变监测领域的应用，并总结了三种典型的应用模式。此外，本文还对伪卫星的位置布设进行了研究，并给出了对布设方案进行评判的几个依据。 2．由GPS和伪卫星的观测量入手，重点研究了伪卫星增强GPS定位的效果。推求了GPOP和VDOP等精度因子的极值表达式以及GDOP的递推关系式，同时证明了GDOP和RGDOP之间的量化关系。从理论上阐明了利用伪卫星技术提高定位精度的根本原因。 3．建立了GPS和伪卫星在不同组合定位方式下的观测模型，分析了GPS和伪卫星在误差来源和误差特性的异同，研究了伪卫星对流层延迟的计算方法和静态环境下多路径偏差的消除方法。此外，针对伪卫星的钟差特性，首次提出了一种计算伪卫星时钟钟差变化率的方法，并采用实验数据进行了验证和钟差拟合分析。结果表明，本文提出的计算方法是有效的。 4．针对GPS和伪卫星组合定位系统，深入研究了模糊度解算、周跳修复、对流层延迟建模和多路径偏差消除等关键问题的算法流程和具体实现，并成功开发了相应的子模块，完成了GPS伪卫星组合定位系统软件的开发工作。 5．针对特定的地理环境条件，利用实测的GPS和伪卫星数据进行了组合定位解算，并对实验数据采取了不同方案的计算和分析。数据处理的结果表明，在有效消除了伪卫星多路径效应后，GPS和伪卫星组合定位技术能显著提高定位精度。更多还原

【Abstract】 Traditional surveying techniques have been more and more difficult to meet the requirements of large-scale deformation monitoring such as dams and landslides in continuity, real time and automation. GPS is an advanced tool for deformation monitoring, and it has been widely applied in geodetic survey, crustal movement monitoring and precise engineering survey. For deformation monitoring of dams and slopes, GPS has already proven to be convenient in data collection, data transmission, data processing and analysis. However, it has problems on the accuracy, reliability as well as the high cost. Under poor observation environments, GPS positioning accuracy decreases significantly because GPS signal is blocked. Moreover, the positioning accuracy of the height component is generally 2 or 3 times worse than the horizontal component due to the limitations of satellite geometry. Furthermore, GPS has still not been used in some areas such as underwater, underground, indoor or tunnels.Pseudolite positioning technique is an effective tool to solve GPS problems above. Pseudolites can increase the number of satellites and improve the geometry. This dissertation will investigate the integration of GPS and pseudolites to improve the positioning accuracy, especially the vertical accuracy in order to meet the requirements of dam and slope deformation monitoring systems. The emphasis in this work has been placed on1. Basic principles and pseudolite signal structure and navigation data were described. Some key issues in the applications of pseudolites, such as the scheme of GPS and pseudolite integration, the near-far problem, pseudolite tropospheric delay, pseudolite synchronization and multipath effects were discussed in detail. Several requirements of pseudolite stations were also proposed in this work.2. Based on the integration of GPS and pseudolites, Geometric DOP was investigated to compare effects of the additional pseudolite observations. The estimations of GDOP and VDOP maximum values were given, and the relationship between GDOP and RGDOP was also demonstrated. These results indicated that the positioning accuracy was improvement by pseudolites augmentation.3. Different observation models for GPS and pseudolites integrated system under different situations were built. Similarities and differences of error characteristics of GPS and pseudolites were compared. The estimation equations for pseudolites tropospheric delay and multipath bias in static environment were also given. Moreover, an effective way was proposed to estimate the parameters of pseudolite clock bias and clock drift by data fitting.4. Based on the observations and error models, a software package for data processing of an integrated GPS and pseudolite system was successfully developed by the author. Some key modules such as ambiguity resolution, cycle slip recovery, tropospheric delay and multipath bias mitigation were demonstrated in this work.5. A static field test was carried out to evaluate the practical effect of GPS and pseudolite integrated positioning system in poor observation environments. And the experimental data has been processed under different scheme using the software developed. It can be seen from the results that the augmentation of pseudolite can improve dramatically positioning accuracy when the pseudolite multipath biases were calibrated in advance.更多还原