Improved determination of group delay variations (GDV) of GNSS transmitter and receiver systems

GNSS码信号的延迟取决于它们的传输和入射角度，通常被称为群延迟变化(GDV)。它们可以从多频率全球导航卫星系统观测数据中确定，并用作代码信号的校正。它们的使用改善了所有那些依赖于准确代码观测的GNSS应用程序的结果。近年来，德累斯顿理工大学大地测量研究所发展了一种测定GDV的方法。它基于码-相-线性组合的分析，并已应用于全球分布的参考站的观测数据，用于确定北斗二号和GPS L1/L2编码信号的随高程变化的GDV。目前的参数化将被扩大到也包括发射和接收系统的GDV的方位相关性。这一方法将适用于许多新的信号频率，并适用于具有各自特性的其他卫星系统。另一个扩展涉及对来自低轨卫星的全球导航卫星系统观测数据的分析，这些卫星为确定全球变化趋势提供了另一个极好的数据来源。所有这些扩展都将形成一种根据全球导航卫星系统观测数据确定全球变化趋势的总体方法。此外，它的应用将为所有全球导航卫星系统卫星和许多大地测量全球导航卫星系统接收系统提供GDV改正数据集。在另一个工作包中，将详细分析不同轨道高度(地球表面、低轨轨道)的接收系统确定绝对GDV的可能性。

GNSS code signals experience delays depending on their transmission and incidence an-gles, often called Group Delay Variations (GDV). They can be determined from multi-frequency GNSS observation data and be used as corrections for the code signals. Their use improves the results of all those GNSS applications that rely on accurate code obser-vations. In recent years a GDV determination method was developed at the Geodetic In-stitute of the TU Dresden. It is based on the analysis of code-phase-linear combinations and has been applied to observation data from globally distributed reference stations for the determination of elevation-dependent GDV of BeiDou-2 and GPS L1/L2 code signals applied.In this research project, the existing methodology of GDV determination will be extended in several aspects. The present parametrization will be enlarged to also cover azimuth dependencies of the GDV of transmitting and receiving systems. The methodology will be adapted to the many new signal frequencies and to additional satellite systems with their individual properties. An additional extension concerns the analysis of GNSS observations from LEO satellites, which provide another excellent data source for GDV determination. All these extensions will result in an overall methodology for GDV determination from GNSS observation data. Furthermore, its application will yield GDV correction data sets for all GNSS satellites and many geodetic GNSS receiving systems. In an additional working package, the potential of absolute GDV determinations from receiving systems at differ-ent orbital heights (earth’s surface, LEO orbits) will be analyzed in detail.