Galileo Precision Receivers Test Campaign

M. Bavaro, D. Borio, J.T. Curran, J. Fortuny-Guasch, C. Gioia, M. Paonni

Abstract:	Following a meeting organized by the GSA on the 19th of March 2013 in Brussels with GNSS receiver manufacturers, where the schedule towards Galileo Early Services declaration was announced, this paper describes the test campaign to support the introduction of Galileo in commercially available high-end receivers and to evaluate their readiness to fully exploit Galileo potentialities. To date, the vast majority of manufacturers of high-precision GNSS receivers have provided the test campaign with receivers representing their most leading-edge technology. The campaign focused on the compatibility of the devices with Galileo Open Service signals and their combined use with GPS. Particular attention was placed upon the evaluation of receivers’ behaviour under non nominal signal reception conditions, natural or manmade, unintentional or malicious. Needless to say, the purpose of the campaign was not to generate a benchmark amongst different manufacturers but to get feedback and recommendations useful to the Galileo community. The JRC provided support to GSA and ESA and addressed so called “professional” receivers. The activity was divided in two branches: bench tests and live tests. Bench tests were carried out in the laboratory, using multi-frequency multi-constellation simulation and record and playback equipment. Reference data-sets were collected in “Open sky” (without obstructions) conditions and characterized by ideal line-of-sight (LOS) signal reception. Observations obtained from such data-sets were used as reference for the further comparative analysis. Bench tests covered reception under the presence of Radio Frequency Interference (CW, chirp, wideband filtered white noise) and tracking during strong ionospheric scintillations. Live tests had the objective of ensuring the optimal synergy between the Galileo signal in space (SIS) and its receiver. The plan foresaw mainly static survey and land mobile based tests and had the objective to verify correct operation of the receiver using actual navigation data broadcast by the SIS including, for example, health flags, inter-constellation time offsets (GGTO), ionospheric parameters and issue of data values. Additionally, the static survey test provided useful insight on multipath performance of Galileo observables whilst the mobile test highlighted Galileo acquisition and re-acquisition times, BER and loss of lock. In carrying out bench tests the hemispherical anechoic chamber available within the GNSS Security Laboratory of the Joint Research Centre (JRC) of the European Commission was used. Equipped with state of the art technology such as a four-channel record and playback device, a multi-constellation multi-frequency simulator and measurement and test instruments, it allows a large variety of RF tests. A database of pre-surveyed ground control points was used for the static live test. A reference trajectory was generated with an integrated inertial and GNSS reference receiver for the vehicular live tests. Specific bench tests were carried out for each class of RFI. Observations were collected both for the measurement and the PV domain. At measurement level, the degradation of pseudorange, range-rate and carrier phase were observed through a comparison between the interfered/jammed measurements and the reference observables. Also, the degradation of C/N0 was considered as a relevant figure of merit. In the position domain, the precision and accuracy of the Single Point Positioning solution was compared against the reference. IF data-sets representative of strong ionospheric scintillations, collected at equatorial regions selected from the existing JRC IF data library, were re-broadcast inside the anechoic chamber. The evaluated figure of merit was availability carrier phase measurements and loss of lock. Being the dominant error source in high precision satellite navigation applications, performance under multipath propagation conditions was measured. In order to evaluate its impact a limited number of accurately geo-referenced monuments representative of real-World multipath conditions was selected in the live static test campaign. Reference measurements were not directly available, thus the computation of the true satellite-receiver distances and clock biases was performed in post-processing assuming the position of the receiver known. Similar figures as above were used here to characterise the degradation in the position and measurements domain. Galileo offers a modernised set of modulations and navigation signals requiring novel acquisition and tracking policies; industry might have adapted to Galileo processing schemes originally developed for GPS, thus not necessarily tailored to exploit its full potential. With this in mind, mobile live test were carried out to investigate the level of maturity of multi-constellation devices. Performance indicators in this case were sensitivity, availability and reacquisition time. In order to evaluate the benefits of the inclusion of the Galileo measurements, the performance of the multi constellation system, obtained combining GPS and Galileo, is compared to GPS only case. Results of are presented in agreement with manufacturers and in an anonymous fashion, in compliance with the confidential nature of the initiative.
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	406 - 432
Cite this article:	Bavaro, M., Borio, D., Curran, J.T., Fortuny-Guasch, J., Gioia, C., Paonni, M., "Galileo Precision Receivers Test Campaign," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 406-432.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In