Spelling suggestions: "subject:"artificial satellite""
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GPS radio occultation and the role of atmospheric pressure on spaceborne gravity estimation over AntarcticaGe, Shengjie, January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 204-215).
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An evaluation of realistic TCP traffic in satellite networksNarasimhan, Priya. January 2002 (has links)
Thesis (M.S.)--Ohio University, August, 2002. / Title from PDF t.p.
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Aircraft position integrity for differential satellite-based navigation in the presence of both bias and noise errorsSuddapalli, Rajesh. January 2004 (has links)
Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (p. 69-71)
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Satellite data transmission by means of a multi-channel system /Smith, David. January 2006 (has links)
Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.
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Frequency allocation, transmit power control, and load balancing with site specific knowledge for optimizing wireless network performanceChen, Jeremy Kang-pen, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
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Multiprocessor implementation of algorithms for multisatellite orbit determination /Nagel, Peter Borden, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 152-162). Available also in a digital version from Dissertation Abstracts.
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Modelling and evaluation of adaptive control techniques in satellite orientation during large actuator gain changesRossouw, Jacques Stefan 04 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Improvements in the area of satellite orientation control in the presence of
large actuator gain changes are investigated. Gain changes primarily originate
from actuator failures, but may also result from intermittent sensor
availability and geomagnetic field effects.
The stability and performance of a classic LQR control solution under these
conditions is analyzed through simulation, and two adaptive schemes are
developed to improve the response.
The adaptive schemes mix elements from bang-bang control to increase performance,
and banded control to increase robustness. These control schemes
are thoroughly tested through simulation and the results are compared with
those obtained for the classic solution.
Extensive modelling of the system in the MATLAB™ environment is done
to support the analysis of the controllers, and hardware sensors are built to
provide realistic orientation measurements to the controllers. / AFRIKAANSE OPSOMMING: Verbeterings in die veld van satelliet oriëntasie beheer in die gevalle waar
die aktueerders groot veranderinge in aanwins toon, word ondersoek. Aanwins
veranderinge word primêr veroorsaak deur aktueerder falings, maar kan
ook deur diskontinue sensor metings en magneetveld effekte van die aarde
veroorsaak word.
Die stabiliteit en gehalte van 'n klassieke LQR beheer strategie onder hierdie
omstandighede word ondersoek deur simulasie, en twee aanpasbare beheer
strategieë word ontwikkelom die oordrag te verbeter.
Die aanpasbare beheer strategieë meng elemente van "bang-bang" beheer
om die gehalte te verbeter, en gebande beheer tegnieke om die robuustheid
van die stelsel te verbeter. Hierdie beheer strategieë is deeglik in simulasies
getoets en die resultate is vergelyk met dié van die klassieke beheerder.
Ekstensiewe modelleering van die stelsel is in die MATLAB™ omgewing gedoen
om die beheerders te analiseer, en hardeware sensore is gebou om realistiese
orientasie metings aan die beheerders te verskaf.
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A second generation SUNSAT RAMDISKRust, A. N. 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The SUNSAT RAMDISK was studied, and tests performed to assess its flight
readiness. Errors were detected, and modifications had to be made to ensure proper
operation. SUNSAT was subsequently launched, and to date the RAMDISK is still
functioning correctly. The flight readiness testing of the RAMDISK was considered a
pre-study to designing a second generation RAMDISK.
A conceptual mass memory storage device support structure was designed. This
second generation RAMDISK, or memory drive is intended to be used on a second
generation SUNSAT, or SUNSAT 2. The design is targeted for implementation in
fields programmable gate arrays (FPGA's) and was realised using VHDL. This
hardware description language is an accepted standard, and can be implemented in a
number of different programmable logic devices; both SRAM and fuse-link based.
Simulations were performed to verity the functionality of the design, and to determine
whether the data transfer specifications could be met using programmable logic
devices.
A modular design methodology was followed. The memory drive was designed so that
any type and amount of memory can be added to the drive without a major design
change.
The simulations indicated that a data capturing speed of 130 Mbits/s could be
maintained. / AFRIKAANSE OPSOMMING: Die SUNSAT massa geheue module is bestudeer, en toetse is daarop uigevoer om die
vlug gereedheid te bepaal. Foute is gevind, en veranderinge moes aangebring word om
korrekte werking te verseker. SUNSAT is gelanseer en die geheue module werk tot op
datum nog korrek. Die geheue module se vlug gereedheid toetse is beskou as In voor
studie vir die ontwerp van In tweede generasie geheue module.
In Konseptueie massa stoor toestel struktuur is ontwerp. Hierdie tweede generasie
geheue module, of geheue skyf is bedoel om op In tweede generasie SUNSAT, of
SUNSAT 2 gebruik te word. FPGA's is die teiken tegnologie vir hierdie ontwerp en
VHDL is gebruik om die ontwerp te realiseer. Hierdie hardeware beskrywingstaal
word as In standaard aanvaar en kan in verskillende herprogrammeerbare tegnologieë
gebruik word.
Sirnulasies is gedoen om die funksionaliteit van die ontwerp te verifieer, en om te
bepaal of die nodige data oordragstempo gehandhaaf kan word met
herprogrammeerbare tegnologie.
In Modulêre ontwerpsfilosofie is gevolg. Die geheue skyf is ontwerp sodat dit enige
tipe en hoeveelheid geheue kan ondersteun sonder om groot veranderinge aan die
ontwerp te doen.
Die sirnulasies toon dat In data oordragstempo van 130 Mbits/s gehandhaafkan word.
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Design of a mobile field station for LEO satellite communicationsErasmus, J. M. (Johan Michiel) 03 1900 (has links)
Thesis (MEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: This document describes the breadboard design and practical evaluation of a mobile
field station, capable of communicating with the SUNSAT micro satellite. A study of
existing satellite communication systems employing LEO satellites, as well as the
physical phenomena, influencing the VHF communication link between earth and
such satellites was done and used to determine the specifications needed for a
functional field station.
The design entailed work on different building blocks like a receiver, transmitter and
modem unit as well as the writing and testing of the necessary software on a
controlling personal computer. The measurements done showed that the field station
satisfies most of the specifications, and that it is capable of communicating with a
satellite. The document is concluded by suggesting improvements and possible further
work before a commercial version of the field station may be build. / AFRIKAANSE OPSOMMING: In hierdie dokument word die ontwerp en praktiese evaluasie van 'n mobiele
veldstasie beskryf wat met die SUNSAT mikrosatelliet kan kommunikeer. 'n
Ondersoek na bestaande satellietstelsels in lae-aard wentelbane en die fisiese faktore
wat die radioskakel tussen die grond en sulke satelliete beïnvloed is gebruik om
spesifikasies vir 'n werkende veldstasie daar te stel.
Die ontwerpstaak het werk aan 'n ontvanger, sender, modem en beheerproggramatuur
ingesluit. Die voltooide veldstasie is gekarakteriseer deur 'n meetproses wat
aangetoon het dat dit met 'n satelliet kan kommunikeer. Die dokument word afgesluit
met voorgestelde verbeterings en verdere werk aan die veldstasie voordat 'n
kommersiële weergawe daarvan voltooi kan word.
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Development of a QPSK demodulator for the Sunsat 1 groundstationKotze, P. P. A. (Pieter Paul Adriaan) 03 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The purpose of this thesis is the description of the development of a QPSK demodulator
for the Sunsat 1 groundstation. A general overview of the functioning and requirements
of a typical QPSK demodulator system is given. Several methods or algorithms for clock
and carrier recovery are discussed. Specific attention is given to the QPSK demodulator
chipset from Philips used for the implementation of the demodulator. The digital
decoding logic used to serialize the parallel I and Q datastream is explained. Finally
measurement techniques for performance evaluation of QPSK systems are investigated.
As part of this the implementation loss of the developed QPSK demodulator is measured. / AFRIKAANSE OPSOMMING: Die doelwit van hierdie tesis is om die ontwikkeling van 'n QPSK demodulator vir die
Sunsat 1 grondstasie te beskryf. 'n Algemene oorsig oor die funksionering en vereistes van
'n tipiese QPSK demodulator stelsel word gegee. Verskeie algoritmes en tegnieke vir klok
en draersein herwinning word ondersoek en bespreek. Spesifieke verwysing word telkens
gemaak na die QPSK demodulasie vlokkie paar van Philips gebruik vir die implementering
van die demodulator. Die digitale dekodering logika benodig vir die datastroom
verpakking word ondersoek en beskryf. Laastens word daar gekyk na meettegnieke en
evaluasie van QPSK demodulasie stelsels se prestasie. As deel hiervan word die implementasie
verlies van die ontwikkelde QPSK demodulator stelsel gemeet.
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