Automated GPS Signal-in-Space Anomalies Monitoring Over More than 11 Years

J. Sanz, J. M. Juan, C. López de Echazarreta, G. Gonzalez-Casado, A. Rovira García, M.T. Alonso, Deimos Ibáñez

Peer Reviewed

Abstract:	This paper presents the results of a performance assessment of GPS constellation based on the International GNSS Service (IGS) data collected from 2004 to 2014. There exist previous analysis of GPS Signal-in-Space (SiS) anomalies which performed the screen out by comparing the broadcast GPS ephemerides and clocks with the precise data provided by IGS or by the National Geospatial-Intelligence Agency (NGA). In this paper, a complementary detection methodology has been developed which targets to detect very short duration events linked to satellite clock and pseudorange jumps. These SiS events are assessed by examining code and carrier phase measurements for a minimum set of IGS receivers worldwide distributed. Short duration (few seconds) satellite clock events are monitored using carrier measurements corrected by the geometric range and linearly interpolated precise satellite clocks at 300 seconds sampling rate. Pseudorange jumps are monitored with the code-minus-carrier combination, where the geometry and frequency dependent effects are removed. Events detected simultaneously on several receivers are recorded, while events that are not confirmed are discarded as receiver artefacts. The results obtained following the application of the methodology are shown in order to offer an overview of the different events and their magnitudes. A total of 124 days with short duration clock events have been detected during the 11 years period analyzed. These events involve 23 GPS satellites, being 72 of such days associated to SVN063. No multiple satellite events have been found in the same day. It is also shown that the implemented code monitor is strongly affected by code multipath and, among all detections, only one code pseudorange jump event has been found, affecting the P1 of satellite SVN 061.
Published in:	Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018) September 24 - 28, 2018 Hyatt Regency Miami Miami, Florida
Pages:	2172 - 2185
Cite this article:	Sanz, J., Juan, J. M., de Echazarreta, C. López, Gonzalez-Casado, G., García, A. Rovira, Alonso, M.T., Ibáñez, Deimos, "Automated GPS Signal-in-Space Anomalies Monitoring Over More than 11 Years," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 2172-2185. https://doi.org/10.33012/2018.15853
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