Direct VLBI Observations of Global Navigation Satellite System Signals
We describe an experiment carried out to observe signals emitted by GLONASS (GLObal NAvigation Satellite System) satellites using the Very Long Baseline Interferometry (VLBI) technique. This test was performed on a single baseline and had as its primary goal to evaluate the capability of the VLBI system to observe GNSS (Global Navigation Satellite System) signals in terms of scheduling, tracking, acquisition, recording, correlation and processing of data. The general aim of such observations is to contribute to the connection of the reference frames for GNSS and VLBI by so-called co-location in space, or space-ties, as a complement to the existing so-called local-ties on the Earth’s surface.
In our experiment we found an interferometric response from both signals emitted by GLONASS satellites and a natural radio source that was observed as a calibrator, using the same VLBI equipment. The derived fringe phase scatters were 80 ps (2.5 cm) and 1.3 ns (39 cm) in 1 s for the GLONASS satellite and the calibrator signals, respectively. This indicates that the accuracy is not limited by GLONASS signals, but by the calibrator.
Our results show that VLBI observations of GNSS signals are possible and have the potential to derive the satellite positions on a centimetre level for observing times of just a few minutes. Future experiments should include several baselines and a larger number of calibrators in close angular distance to the satellite tracks to allow frequent switching between calibrator and satellite signals.
KeywordsGNSS Local-ties Reference frames Space-ties VLBI
This work is based on observations with the Medicina radio telescope, operated by INAF, Istituto di Radioastronomia, Italy, and the Onsala85 radio telescope, operated by the Swedish National Facility for Radio Astronomy, Sweden. The authors wish to thank the personnel at the VLBI stations of Medicina and Onsala, and the processing center at the Joint Institute for VLBI in Europe (JIVE) for supporting the experiments. V. Tornatore thanks MIUR (Ministry of Education of University and Research) for funding in the framework of the PRIN (Project of considerable National Interest, 2008, F. Sansó National Coordinator).
- Bar-Sever Y, Bertiger W, Desai S, Gross R, Haines B, Wu S, Nerem S (2011) Geodetic Reference Antenna in Space (GRASP): a mission to enhance GNSS and the terrestrial reference frame. http://www.pnt.gov/advisory/2011/06/bar-sever.pdf. Accessed 10 Aug 2012
- Born M, Wolf E (2002) Principles of optics, 7th edn. Cambridge University Press, CambridgeGoogle Scholar
- Clark TA, Thomsen P (1988) NASA Technical Memorandum 100696, GreenbeltGoogle Scholar
- Duev D, Molera Calvés G, Pogrebenko SV, Gurvits LI, Cimo G, Bocanegra Bahamon T (2012) Spacecraft VLBI and Doppler tracking: algorithms and implementation. A&A 541(A3):1–9Google Scholar
- Greisen EW (1998) The creation of AIPS. AIPS Memo 100. NRAO, Socorro. http://www.aips.nrao.edu/aipsmemo.html. Accessed 10 Aug 2012
- Keimpema KA, Duev DA, Pogrebenko SV (2011) Spacecraft tracking with the SFXC software correlator. In: URSI-BeNeLux 06.06.2011, ESTEC, The NetherlandsGoogle Scholar
- Kovalevsky J, Mueller II, Kolaczek B (eds) (1989) Reference frames in astronomy and geophysics. Kluwer Academic, DordrechtGoogle Scholar
- National Research Council (2007) Earth science and applications from space: national imperatives for the next decade and beyond. The National Academies, Washington, DC. ISBN 978-0-309-14090-4Google Scholar
- National Research Council (2010) Precise geodetic infrastructure: national requirements for a shared resource. The National Academies, Washington, DC. ISBN 978-0-309-15811-4Google Scholar
- Nothnagel A, Angermann D, Börger K, Dietrich R, Drewes H, Görres B, Hugentobler U, Ihde J, Müller J, Oberst J, Pätzold P, Richter B, Rothacher M, Schreiber U, Schuh H, Soffel M (2010) Space–time reference systems for monitoring global change and for precise navigation. Mitteilungen des Bundesamtes für Kartographie und Geodäsie, Band 44. Verlag des Bundesamtes fur Kartographie und Geodäsie, Frankfurt am MainGoogle Scholar
- Petit G, Luzum B (eds) (2010) IERS conventions. IERS technical note 36. Verlag des Bundesamts für Kartographie und Geodäsie, Frankfurt am Main. http://tai.bipm.org/iers/conv2010/. Accessed 10 Aug 2012
- Preston RA, Hildebrand CE, Ellis J, Finley SG, Purcell GH, Stelzried CT, Sagdeev RZ, Linkin VM, Akim EL, Aleksandrov YN, Altunin VI, Armand NA, Bakitko RV, Bogomolov AF, Gorshankov YN, Ivanov NM, Kerzhanovich VV, Kogan LR, Kostenko VI, Matveenko LI, Pogrebenko SV, Selivanov AS, Strukov IA, Tichonov VF, Vyshlov AS, Blamont J, Biraud F, Boischot A, Boloh L, Laurans G, Ortega-Molina A, Petit G, Rosolen C (1986) Determination of Venus winds by ground-based radio tracking of the VEGA balloons. Science 231(4744):1414–1416CrossRefGoogle Scholar
- Tornatore V, Haas R, Duev D, Pogrebenko S, Casey S, Molera Calvés G, Keimpema A (2011) Single baseline GLONASS observations with VLBI: data processing and first results. In: 20th (European VLBI for Geodesy and Astrometry) EVGA working meeting proceedings, MPIfR, Bonn, 29–31 March 2011, 162–165. ISSN 1864-1113Google Scholar
- Wagner J, Molera Calvés G, Pogrebenko SV (2009–2010) Metsähovi software Spectrometer and Spacecraft Tracking tools, software release (GNU-GPL). http://www.metsahovi.fi/en/vlbi/spec/index. Accessed 10 Aug 2012