The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
S. F. Likhachev - One of the best experts on this subject based on the ideXlab platform.
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Tropospheric Effect on the Transmissivity of the Spacecraft–Ground Tracking Station Communication Line
Cosmic Research, 2019Co-Authors: M. N. Andrianov, V. I. Kostenko, S. F. LikhachevAbstract:Algorithms ensuring high-speed and reliable data transmission under lognormal amplitude fluctuations (described by Fraunhofer diffraction) in the spacecraft–ground Tracking Station line for coherent and incoherent reception of signals have been considered. An advantage of the coherent reception of millimeter-range signals with a random error-correcting code has been indicated.
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On increasing the spectral efficiency and transmissivity in the data transmission channel on the spacecraft-ground Tracking Station line
Cosmic Research, 2018Co-Authors: M. N. Andrianov, V. I. Kostenko, S. F. LikhachevAbstract:The algorithms for achieving a practical increase in the rate of data transmission on the space-craft–ground Tracking Station line has been considered. This increase is achieved by applying spectral-effective modulation techniques, the technology of orthogonal frequency compression of signals using millimeterrange radio waves. The advantages and disadvantages of each of three algorithms have been revealed. A significant advantage of data transmission in the millimeter range has been indicated.
Oliver Montenbruck - One of the best experts on this subject based on the ideXlab platform.
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Kalman-filter-based GPS clock estimation for near real-time positioning
GPS Solutions, 2009Co-Authors: André Hauschild, Oliver MontenbruckAbstract:In this article, an algorithm for clock offset estimation of the GPS satellites is presented. The algorithm is based on a Kalman-filter and processes undifferenced code and carrier-phase measurements of a global Tracking network. The clock offset and drift of the satellite clocks are estimated along with Tracking Station clock offsets, tropospheric zenith path delay and carrier-phase ambiguities. The article provides a brief overview of already existing near-real-time and real-time clock products. The filter algorithm and data processing scheme is presented. Finally, the accuracy of the orbit and clock product is assessed with a precise orbit determination of the MetOp satellite and compared to results gained with other real-time products.
M. N. Andrianov - One of the best experts on this subject based on the ideXlab platform.
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Tropospheric Effect on the Transmissivity of the Spacecraft–Ground Tracking Station Communication Line
Cosmic Research, 2019Co-Authors: M. N. Andrianov, V. I. Kostenko, S. F. LikhachevAbstract:Algorithms ensuring high-speed and reliable data transmission under lognormal amplitude fluctuations (described by Fraunhofer diffraction) in the spacecraft–ground Tracking Station line for coherent and incoherent reception of signals have been considered. An advantage of the coherent reception of millimeter-range signals with a random error-correcting code has been indicated.
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On increasing the spectral efficiency and transmissivity in the data transmission channel on the spacecraft-ground Tracking Station line
Cosmic Research, 2018Co-Authors: M. N. Andrianov, V. I. Kostenko, S. F. LikhachevAbstract:The algorithms for achieving a practical increase in the rate of data transmission on the space-craft–ground Tracking Station line has been considered. This increase is achieved by applying spectral-effective modulation techniques, the technology of orthogonal frequency compression of signals using millimeterrange radio waves. The advantages and disadvantages of each of three algorithms have been revealed. A significant advantage of data transmission in the millimeter range has been indicated.
Kwo-hwa Chen - One of the best experts on this subject based on the ideXlab platform.
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The Impact on the Positioning Accuracy of the Frequency Reference of a GPS Receiver
Surveys in Geophysics, 2013Co-Authors: Ta-kang Yeh, Chieh-hung Chen, Chuan-sheng Wang, Kwo-hwa ChenAbstract:Despite the pervasive use of the global positioning system (GPS) as a positioning technology for its high efficiency and accuracy, several factors reduce its performance. This study examines to which extent the frequency offset and the frequency stability of the internal quartz oscillator or of an externally supplied rubidium oscillator have an influence. Observations were made at the Taiwan Ching Yun University (TCYU) Tracking Station, where a quartz oscillator and a rubidium oscillator were applied alternatively on a monthly basis throughout a 16-month period. Moreover, the accuracy of the local oscillator used in this study was calibrated by the National Standard Time and Frequency Laboratory, Taiwan. The frequency offset and frequency stability calculated via the remote method at the TCYU Station were compared with values (uncertainty is 3.0E−13) measured directly at the National Standard Time and Frequency Laboratory, Taiwan. Analytical results show that the two methods vary by 1.4E−10 in terms of frequency offset and by 6.5E−12 in terms of frequency stability, demonstrating that the remote method can yield computational results almost as accurate as direct measurement. Positioning precision results also show that rubidium oscillator accuracy improved by 5, 11, and 15 % for short-, medium-, and long-baseline positioning, respectively, indicating that clock quality is more influential for long-baseline GPS relative positioning and that the frequency stability of a receiver clock is far more critical than the frequency offset. On the other hand, the positioning performance noted is essentially independent (max. 15 % change) of the reference frequency stability, which indeed differed by 4 orders of magnitude.
Hugo Palmarola - One of the best experts on this subject based on the ideXlab platform.
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NASA in Chile: Technology and Branding of a Satellite-Tracking Station
Design Issues, 2017Co-Authors: Pedro Ignacio Alonso, Hugo PalmarolaAbstract:In 1957 as part of the Minitrack Network, the U.S. Army installed a satellite-Tracking Station in Peldehue, Chile, intended to track radio signals from what was then the United States’ Vanguard pro...
