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Ultra low frequency (ULF) waves observed at mid to low latitudes during daytime using low Earth orbit (LEO) satellite and ground-based data.Ndiitwani, Dzivhuluwani Christopher. January 2011 (has links)
The launch of German geoscience satellite CHAMP inspired the increased interest in the study
of ultra low frequency waves. In this work data from low Earth orbiting (LEO) German CHAMP
satellite and South African ground-based magnetometer data were used to study geomagnetic
pulsations, in particular continuous pulsations, Pc3, with periods in the range 10-45 seconds.
Both Fast Fourier Transform (FFT) and Maximum Entropy Spectral Analysis (MESA) were
used as analysis techniques to compute and compare spectra. We simulated a Pc3 oscillation
using a sinusoidal function in order to test and establish appropriate parameters to use on the
application of these analysis techniques. In this study the region chosen for a low latitude
geomagnetic pulsations study excludes high current regions such as polar regions where field
aligned currents occur. The structure of low-latitude pulsations was studied by comparing satellite and ground magnetic field measurements. The magnetic field measurements observed in
the topside ionosphere by CHAMP were compared to Hermanus data for times when CHAMP
crossed the ground station L-shell. The data were analysed for Pc3 pulsation activity using
the MESA method to visualise field line resonance (FLR) in the vector magnetometer data. A
number of discrete frequency oscillations for the fast mode wave were observed, one of which
drives FLR at characteristic latitude as detected by both ground and satellite measurements.
The toroidal mode frequency on CHAMP experiences a Doppler shift due to the rapid motion
across the resonance region. Polarization hodograms in the resonance region show the expected
900 rotation of the field line resonant magnetic field components. We present first time ob-
servations of toroidal standing Alfv´en mode oscillation with clearly L-dependent frequencies
in the inner magnetosphere for L < 3. Our observations show FLR frequency continuously
increasing as a function of decreasing latitude down to L = 1.6 and then decrease as a result of
the larger plasma density of the upper ionosphere. The L-dependent frequency oscillations were
observed in the presence of broadband compressional wave spectra. Our observation confirms
the well-known magnetohydrodynamic (MHD) wave theoretical prediction of a compressional
wave being the driver of the field line resonance, and that the Pc3 pulsations do not have a
source with the same frequency structure.
Keywords: ULF waves, Fast Fourier Transform, Maximum Entropy Spectral Analysis, CHAMP
satellite, Geomagnetic pulsations, Pc3, Alfv´en wave, Field line resonance. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.
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An analysis of the circularization of elliptic satllite orbits caused by atmospheric dragCowley, John Rosette 12 1900 (has links)
No description available.
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273 |
Data transmission via satellites for aircraft malfunction detection and predictionFontaine, Bernard Alain 05 1900 (has links)
No description available.
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274 |
Interplatform links /Purvinskis, Robert Andrew Janis. Unknown Date (has links)
Thesis (MEng(Telecommunications))--University of South Australia, 2003.
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275 |
Doppler compensation for LEO satellite communication systems /Ah-Thew, George Patrick. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (p. 251-271). Also available via World Wide Web.
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276 |
Control of a satellite based photovoltaic array for optimum power drawCooper, Sean. January 2008 (has links)
Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: photovoltaic; solar satellite; optimize; dc-dc. Includes bibliographical references (leaves 51).
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277 |
Theory, design and implementation of a digital receiver for the Advanced Communications Technology Satellite (ACTS) beacons /Sylvester, William R., January 1992 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / 1 ill. in back pocket. Vita. Abstract. Includes bibliographical references (leaves 224-228). Also available via the Internet.
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278 |
Study of slant path attenuation ratios derived from a dual-polarized radar /Pollard, Kimberley Jeanne, January 1990 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 130-133). Also available via the Internet.
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279 |
L'U.I.T. [Union internationale des télécommunications] et les télécommunications par satellites /Garmier, Jacques. January 1975 (has links)
Thèse--Sc. pol.--Genève, 1973. / Bibliogr. p. 311-323. Index.
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280 |
Recalage d'images multi-sources : application au recalage d'une image spot et d'une carte /Roux, Michel, January 1993 (has links)
Th. doct.--Signal et images--Paris--ENST, 1992. / Bibliogr. 167-181. Résumé en français et en anglais.
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