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| 2. |
- Kodet, Jan, et al.
(författare)
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Co-locations of Space Geodetic Techniques on Ground and in Space
- 2014
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Ingår i: IVS 2014 General Meeting Proceedings "VGOS: The New VLBI Network", Edited by Dirk Behrend, Karen D. Baver, and Kyla L. Armstrong, Science Press (Beijing). - 9787030429742
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Litvinov, Dmitry, et al.
(författare)
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Probing the gravitational redshift with an Earth-orbiting satellite
- 2018
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Ingår i: Physics Letters, Section A: General, Atomic and Solid State Physics. - : Elsevier BV. - 0375-9601. ; 382:33, s. 2192-2198
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Tidskriftsartikel (refereegranskat)abstract
- We present an approach to testing the gravitational redshift effect using the RadioAstron satellite. The experiment is based on a modification of the Gravity Probe A scheme of nonrelativistic Doppler compensation and benefits from the highly eccentric orbit and ultra-stable atomic hydrogen maser frequency standard of the RadioAstron satellite. Using the presented techniques we expect to reach an accuracy of the gravitational redshift test of order 10−5, a magnitude better than that of Gravity Probe A. Data processing is ongoing, our preliminary results agree with the validity of the Einstein Equivalence Principle.
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| 4. |
- Tornatore, Vincenza, et al.
(författare)
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Determination of GLONASS satellite coordinates with respect to natural radio sources using the VLBI technique: preliminary results
- 2011
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Ingår i: Proceedings of the European Test and Telemetry Conference ETTC2011, Toulouse, France.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this manuscript is topresent tests that have been carried out using VLBI (VeryLong Baseline Interferometry) in order to evaluate if thistechnique, primarily a radio astronomical technique, canalso be used to determine positions of Earth orbitingsatellites. A number of GLONASS (Global NavigationSatellite Systems) satellites, usually used for navigationand positioning purposes, were simultaneously trackedwith two European VLBI radio telescopes in geodeticmode. Software, developed for VLBI tracking ofspacecraft, was successfully used for the processing ofthese GLONASS observations. First results are presentedand discussed.
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| 5. |
- Tornatore, Vincenza, et al.
(författare)
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Direct VLBI Observations of Global Navigation Satellite System Signals
- 2014
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Ingår i: International Association of Geodesy Symposia. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0939-9585. ; 139, s. 247-252
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Konferensbidrag (refereegranskat)abstract
- We describe an experiment carried out to observe signals emitted by GLONASS (GLObalNAvigation 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 toevaluate the capability of the VLBI system to observe GNSS (Global Navigation SatelliteSystem) signals in terms of scheduling, tracking, acquisition, recording, correlation andprocessing of data.
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| 6. |
- Tornatore, Vincenza, et al.
(författare)
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Tracking of GLONASS satellites by VLBI radio telescopes
- 2010
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Ingår i: Proc. of the 5th ESA International Workshop on Tracking, Telemetry and Command Systems for Space Applications, TTC 2010, ESA-ESTEC.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several tests to observe signals transmitted by GLONASS (GLObal NAvigation Satellite System) satellites have been performed using the VLBI (Very Long Baseline Interferometry) technique. The radio telescopes involved in these experiments are Medicina and Onsala. The satellites transmit artificial radio signals that were considered in a similar way as natural radio signal that are emitted by natural radio sources. The signal strength of satellite signals is much stronger than the signal strength of natural radio signals, so in order to avoid overload of the telescope frontends, corresponding signal attenuation was applied. Observations at the stations were performed using the standard Mark4 VLBI data acquisition rack and Mark5A disk-based recorders. The goals of the observations were to develop and test the scheduling, signal acquisition and processing routines to verify the full tracking pipeline, foreseeing the cross-correlation of the recorded data on the baseline Onsala-Medicina. The natural radio source 3C454.3 was used as a calibrator before the beginning of the satellite observation sessions.We present results of a detailed analysis of the signal recorded at the Onsala telescope together with a first attempt of cross-correlation of data recorded on the baseline Onsala–Medicina.Further plans to perform new GNSS observations are in preparation, and a study to develop the VLBI delay model for GNSS observations with astronomical VLBI telescopes is in progress.
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