title: Navigation and timing performance monitoring: the GIOVE Mission experience
Creators: name: Galluzzo, Gaetano
Publisher: name: University of Glasgow
Year: 2012
Subjects: subject: GNSS, Galileo, GNSS performance monitoring

description: This thesis is the result of the author’s research activities within the Galileo Project, driven by ESA’s demand to implement navigation performance monitoring capabilities in the early stages of this programme. The main task concerned the development, implementation and testing of an operational Key Performance Indicators (KPI) platform within the so-called GIOVE Mission Segment (GIOVE-M), which represents the experimental stage of the Galileo system prior to the launch of the first set of 4 fully operational Galileo satellites, expected in 2011-2012.
 Since 2005 the GIOVE-M, comprising two GIOVE experimental satellites, the GIOVE Processing Centre (GPC) at ESTEC and the worldwide network of 15 sensor stations, has been conceived as a risk mitigation program according to the incremental development approach adopted for the Galileo system. The GIOVE-M purpose was to assess enough in advance, before the operational system deployment, critical on-board technology, such as the innovative Passive Hydrogen Maser (PHM) atomic clock, as well as on-ground processing facilities and operation capabilities. 
 In this context, the first objective of the present thesis was to contribute to the GIOVE-M experimentation activities through the critical interpretation of the results obtained through a set of KPIs. Although most of the implemented performance monitoring metrics are derived from existing methodologies implemented in previous phases of the Galileo project (Galileo System Test Bed-V1) or other GNSS missions, there are many peculiarities in the actual tailoring of these indicators to the GIOVE-M context, resulting from the author’s critical analysis of the most adequate assessment methods available.
 An overview of the KPI functional software architecture along with the description of the processing models involved is provided in detail in throughout the thesis. 
 More specifically, the KPI cover various areas directly related to the end user’s navigation performance such as the broadcast navigation message data accuracy in terms of the Signal In Space Ranging Error (SISRE), the navigation message latency and the broadcast Galileo to GPS Time Offset (GGTO) accuracy. In addition, the quality of the orbit determination and time synchronization (ODTS) processing is also assessed through the KPI.
 Furthermore, in order to provide the reader with a comprehensive understanding of the GPC operations framework in which the KPI platform is integrated, an overview of the principal operational and functional chains is presented.
 The second part of the thesis is devoted to the characterization of the novel on-board atomic clocks, while also proving the sufficient background on methodologies for clock stability analysis. In particular, an important aspect has been to assess the impact of the PHM frequency stability on the final user performance. All KPI are analysed and validated through real mission data obtained during the 2009-2011 timeframe. 
 The thesis concludes by reporting on the major interest of the KPI with regards to the future Galileo operations in particular in terms of consolidation of the mission support facilities needs, as well as highlighting areas for further development.