| Zugriffsnummer | 34577 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Relative calibration of Galileo Receivers within the Time Validation Facility (TVF) |
| Autor(in); Institution |
Piriz, Ricardo; GMV, Madrid, SPAIN
Rodríguez, D.; GMV, Madrid, SPAIN
Roldan, P.; GMV, Madrid, SPAIN
Mudrak, A.; ESA-ESTEC, Noordwijk, THE NETHERLANDS
Bauch, Andreas; 4.4, Zeit und Frequenz, PTB-Braunschweig
Leute, Julia; 4.4, Zeit und Frequenz, PTB-Braunschweig
Panek, P.; UFE, Prague, CZECH REPUBLIC
Kuna, A.; UFE, Prague, CZECH REPUBLIC
|
| Quelle/Jahr | 2015 Joint Conference of the IEEE International Frequency Control Symposium & the European Frequency and Time Forum:(2015), 245 - 249 |
| ISBN | 978-1-4799-8866-2 |
| Berichtsnummer | CFP15FRE-ART |
| Verlag | Piscataway, NJ: IEEE |
| Konferenzangaben | 2015 Joint IEEE International Frequency Control Symposium and 29th European Frequency and Time Forum, Denver, Colo., 12-16, April, 2015, USA |
| Freie Schlagworte | Time Validation Facility ; Calibration of Galileo Receivers ; Galileo System Time (GST) ; UTC |
| Zusammenfassung | GMV is the prime contractor for the Time and Geodetic Validation Facility (TGVF) in the Galileo FOC phase (Full Operational Capability), a contract of the European Space Agency (ESA). Within the TGVF, the Time Validation Facility (TVF) is the subsystem in charge of steering Galileo System Time (GST) to UTC, among other duties. The TVF is operated at GMV headquarters in Madrid, Spain. Calibrated Galileo receivers are needed in the frame of TVF activities to, among other tasks, assess the GSTUTC offset broadcast in the Galileo navigation message. In a calibrated Galileo receiver connected to a UTC(k) time scale, generated CGGTTS files provide the offset between UTC(k) and GST estimated from the signals of each Galileo satellite in view. Averaging satellites per epoch and applying the UTC-GST offset from the Galileo Signal-In-Space (SIS) we obtain the UTC(Galileo SIS)-UTC(k) difference, which is monitored on a daily basis. Absolute receiver calibration is a complex activity involving the availability of a signal simulator and a calibrated reference antenna. An alternative data-based method to evaluate the Galileo receiver delay in E5 signals has been proposed by ORB [1]. The key feature of the proposed method is the cancellation of the GPS and Galileo ionospheric delays when combining pseudoranges from two satellites with a close position in the sky. It is assumed that the receiver GPS L1 and L2 delays and the Galileo E1 delay are known. Differential Code Biases (DCBs) for GPS and Galileo satellites are also needed as input. The method has been validated at ESTEC by comparing results from a PolaRx4 with the ones obtained from a timing Test User Receiver which had absolute calibration. The results were consistent at nanosecond level. Normally the GPS L1 and L2 delays of a new receiver can be easily calibrated relative to an existing calibrated receiver connected to the same antenna (or an antenna nearby) and to the same clock or time reference. The Galileo E1 delay should be similar but not identical to the GPS L1 delay, given the shared frequency but different modulations involved. For Septentrio receivers, the manufacturer states that the difference should be at the sub-nanosecond level. DLR [2] measured a difference of 0.9 ns between the two biases on a Septentrio PolaRx4, using absolute calibration techniques. For other receiver types larger differences have been found. A software tool called gecal has been developed by GMV within the Galileo TVF, implementing the ORB method and processing RINEX 3.x observation files. Satellite positions are read from a SP3 orbit file. The tool allows the rapid E5 calibration of a new or existing Galileo receiver. So far three receivers have been calibrated in the frame of TVF activities: a PolaRx4 at UTC(ESTEC); a GTR51 and a PolaRx4 at UTC(PTB). The PolaRx4 at PTB is at the core of a new Galileo Experimental Sensor Station (GESS) installed at PTB (named GPTB), thus becoming the first fully calibrated station of the Galileo infrastructure. This paper describes in detail the gecal tool and the calibration results obtained for the three Galileo receivers used in the TVF. Galileo SIS validation results obtained using such receivers are also presented. [1] P. Defraigne et al., Calibration of Galileo signals for time metrology, IEEE transactions on Ultrasonics, Ferroelectrics, and Frequency control 12/2014 61(12):1967-75. [2] B. P. B. Elwischger, S. Thoelert, M. Suess, J. Furthner (DLR), "Absolute Calibration of Dual Frequency Timing Receivers for Galileo", European Navigation Conference ENC 2013, 23.-25. Apr. 2013, Vienna, Austria. |
Zitierung
Piriz, R., Rodríguez, D., Roldan, P., Mudrak, A., Bauch, A., Leute, J., Panek, P., & Kuna, A. (2015). Relative calibration of Galileo Receivers within the Time Validation Facility (TVF). 2015 Joint IEEE International Frequency Control Symposium and 29th European Frequency and Time Forum, Denver, Colo., 12-16, April, 2015, USA.