Thesis (M.S.)--Naval Postgraduate School, 1982. / "June 1982." Includes bibliographical references (p. 60-61).

Thesis (M.A.)--The University of North Carolina at Greensboro, 2010. / Directed by Roy Stine; submitted to the Dept. of Geography. Title from PDF t.p. (viewed Jul. 19, 2010). Includes bibliographical references (p. 89-93).

Thesis (PhD)-Open University. BLDSC no.DX190076.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.

Thesis (MScEng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The purpose of this study was to investigate the feasibility of a moon sensor as an alternative or supplemental sensor to supply attitude information to a satellite. The visibility of the moon was evaluated with regards to that of the sun from a satellite (i.e. the feasibility of the moon sensor is compared to that of a sun sensor). An algorithm was developed to calculate the center of the moon, regardless of phase or rotation, to offer increased accuracy of the center of the moon. The accuracy of this algorithm and the possible error margins were evaluated and discussed in both ideal and actual test cases. The sensor was implemented on embedded hardware. The conclusion of the feasibility analysis was that the sensor would function well as a supplemental sensor (e.g. in conjunction with a sun-sensor) rather than as an alternative sensor. The accuracy of the moon center algorithm was satisfactory for attitude deterrnina tion. This sensor could thus be seriously considered for use on a future satellite. / AFRIKAANSE OPSOMMING: Die doel van die studie is om die lewensvatbaarheid van 'n maan-sensor, as alternatiewe of aanvullende sensor, om oriëntasie data aan 'n sateliet te verskaf, te ondersoek. Die sigbaarheid van die maan en die sigbaarheid van die son is met mekaar vergelyk, vanaf 'n sateliet (m.a.w. die uitvoerbaarheid van 'n maan-sensor is vergelyk met dié van 'n son sensor). 'n Algorittne is ontwikkel om die middelpunt van die maan, ongeag van fase of rotasie, te bereken om verhoogde akuraatheid van die maan se middelpunt te bied. Die akuraatheid van die maan-middelpunt algoritme en moontlike foute is evalueer en bespreek in beide ideale sowel as werklike toets gevalle. Die sensor was op hardeware geimplenteer. Die gevolgtrekking van die lewensvatbaarheids analise is dat die sensor effektief sal funksioneer as 'n aanvullende sensor (d.w.s saam met 'n son sensor) eerder as 'n alternatiewe sensor. Die resultate verkry van die evaluasie van die maan-middelpunt algoritme is bevredegind en is voldoende vir oriëntasie bepaling. Die sensor kan dus ernstig oorweeg word vir gebruik op 'n sateliet in die toekoms.

Thesis (MScEng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The use of commercial-off-the-shelf components in low earth orbit (LEO) satellite systems has become a very popular design trend. Not only are many of these components sufficiently radiation tolerant, but are also less expensive than their space qualified counterparts. Commercial processors are already used in the on-board computer (OBC) of satellites like SUNSAT 2004, CanX and SNAP-I. With the increasing demand for smaller, less expensive satellites and a shorter time-to-market window, the feasibility of implementing a satellite's OBC as a system-on-a-chip (SoC) is now considered. This thesis describes a single-chip implementation, excluding memory, of a LEO microsatellite's OBC on the commercial grade Altera Excalibur embedded processor. A typical satellite OBC system was developed on the Excalibur device to test the functionality and performance of the device as a single-chip OBC. / AFRIKAANSE OPSOMMING: Die gebruik van kommersiële komponente in lae aardwentelbaan satelliet stelsels het 'n baie gewilde ontwerps neiging geword. Meeste van hierdie komersiële komponente is nie net voldoende bestand teen die radiasie in die ruimte nie, maar boonop goedkoper as soortgelyke komponente wat spesifiek vir de ruimte vervaardig is. Kommersiële verwerkers word alreeds gebruik in die aanboord rekenaar (AR) van satelliete soos SUNSAT 2004, CanX and SNAP-I. Met die aahoudende aanvraag vir kleiner, goedkoper en 'n korter ontwikkelings tydperk, word die implementering van 'n satelliet se AR as 'n stelsel-op-'nskyfie nou oorweeg. Hierdie tesis beskryf 'n enkel-skyfie implementasie, geheue uitgesluit, van 'n lae aardwentelbaan mikrosatelliet se AR op die kommersiële Altera Excalibur geïntregreerde verwerker. 'n Tipiese AR stelsel was ontwikkelop die Excalibur verwerker om die funksionaliteit en werkverrigting van die toestel as 'n enkel-skyfie AR te toets.

Thesis (MEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The Attitude Determination and Control System (ADCS) of the Stellenbosch University Satellite (SUNSAT I) is an integrated system providing some redundancy and the necessary data management to control the spacecraft. However, the redundancy is not easily accessible and there is a lack in flexibility when testing individual modules during integration or when the system needs to be extended. The objective of this thesis was thus to develop a high reliability, flexible, modular communication system that included some type of redundancy to manage real-time data and to prevent severe malfunctioning of the entire system. The first step in the project's development methodology was to summarise the requirements and specifications by studying the current ADCS architecture and data management. An investigation into the Controller Area Network (CAN) protocol showed that this technology would fit the requirements very well, leading to the design and implementation of several concept topologies based on CAN. Thereafter, a demonstration model consisting of three prototype nodes was composed. The performance of the so called dual CAN node was analysed and an extrapolation was 'made to determine whether the architecture could support the complete ADCS. It was demonstrated that the dual CAN node provides enough room to accommodate all the processors, actuators and sensors of the ADCS. At the same time, it was shown that reliability and robustness was increased by enhanced redundancy at a node-level as well as at the greater system-level. A dual CAN bus was provided for redundancy at a node-level. At the system-level, the command and data-gathering modules (ACP or OBC's) can now effectively be multiplexed on the network of actuators and sensors. Furthermore, it was shown that error detection capabilities and diagnostics can be enhanced and the complexity of the communication architecture and related wiring harnesses can be reduced. This allows easier access to modules and simplifies development. / AFRIKAANSE OPSOMMING: Die Attitude Determination and Control System (ADCS) van Stellenbosch University Satellite (SUNSAT I) is 'n geïntegreerde stelsel wat voorsiening maak vir 'n mate van oortolligheid en 'n vermoeë om stelseldata te bestuur vir goeie satellietbeheer. Nietemin, hierdie oortolligheid is nie baie toeganklik nie en daar is 'n gebrek aan aanpasbaarheid tydens die toets en integrasie van individuele modules of moontlike stelseluitbreidings. Die doelwit van hierdie tesis was dus die ontwikkeling van 'n betroubare, aanpasbare, modulêre kommunikasie stelsel wat 'n tipe oortolligheid insluit sodat intydse data bestuur kan word en algehele stelselondergang vermy kan word. Die eerste stap in die projek se ontwikkelings metodiek was om 'n opsomming te verkry van die vereistes en spesifikasies deur die huidige ADCS se argitektuur en databestuur te ondersoek. 'n Ondersoek na die Controller Area Network (CAN) protokol het getoon dat hierdie tegnologie aan baie van die vereistes voldoen. Dit het aanleiding gegee tot die ontwerp en implementering van 'n paar konsep ontwerpe gebaseer op CAN. Daarna is 'n demonstrasie model bestaande uit drie prototipe nodusse gebou. Die werksverrigting van die sogenoemde dual CAN node, is ondersoek en 'n ekstrapolasie was gemaak om vas te stelof die argitektuur die volkome ADCS kan huisves. Deur demonstrasie was daar getoon dat die dual CAN node wel genoeg ruimte verskaf om al die verwerkers, aktueerders en sensors van die ADCS te akkommodeer. Daar was terselfdertyd getoon dat betroubaarheid en robuustheid verhoog is deur die verbeterde oortolligheid op 'n node-vlak sowel as op die groter stelsel-vlak. 'n Dubbele CAN bus is gebruik vir oortolligheid op 'n node-vlak. Op 'n stelsel-vlak kan die bevel-en-dataversamelings modules (ACP en aBC's) effektief gemultipleks word op die netwerk van aktueerders en sensors. Daar was verder getoon dat die foutopspoorings vermoeë en diagnostiese vermoeë verbeter kan word en die kompleksiteit van die kommunikasie argitektuur en ooreenkomstige kabelharnasse vereenvoudig kan word. Die gevolg is vereenvoudigde toegang tot modules en vergemaklikde opgradering.

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The aim of the thesis is the design of an economical do - it - yourself ground station for school pupils to communicate with SUNSAT 1. The ground station should also be more economical than a hand - held transceiver radio. The do - it - yourself requirement is there to arouse an interest in electronics, radio frequency electronics and satellite communications in school pupils. A system-level design was done for a ground station consisting of modules which may be bought individually as do - it - yourself kits to eventually produce a full set. The modules are a VHF receiver, a VHF transmitter, a UHF down converter and a modem. Each module has functions which aid in the process of communications (data as well as voice) between the satellite and the ground station. A VHF receiver was designed and implemented to be capable of receiving RF signals from SUNSAT 1. A crystal controlled oscillator was designed that oscillates with a frequency tolerance of less than or equal to ± 0.003 % when aligned without the necessary IlF equipment. An economical Broadband Signal Generator was implemented with a 74ACT14 logic IC, which may be used to align the receiver. The higher harmonics of a square wave with a fundamental frequency of 4 kHz are used as a RF source. A sound card was utilised as a modem to receive 1200 baud AFSK (AX.25 protocol) data and the software was also used to display the data on PC. The data was transmitted from another ground station / AFRIKAANSE OPSOMMING: Die doel van die tesis is die ontwerp van 'n ekonomiese doen - dit - self - grondstasie vir skoolkinders om met SUNSAT I te kan komunikeer. Die grondstasie moet ook meer ekonomies wees as 'n handstelradio. Die doel van die doen - dit - self - beginsel is om die belangstelling in elektronika, RF elektronika and satelliete by skoolkinders aan te moedig. 'n Stelsel ontwerp van 'n grondstasie is gedoen wat bestaan uit modules wat afsonderlik as doen - dit - self - modules aangeskaf kan word om so tot 'n totale grondstasie op te bou. Die modules is die "VHF" - ontvanger, "VHF" - sender, UHF - afmenger en 'n modem. Elke module verskaf funksies wat bydra om met SUNSAT I te kan kornmunikeer. 'n VHF - ontvanger wat in staat is om RF - seine vanaf SUNSAT I te ontvang is ontwerp en gebou. 'n Kristal b heerde ossillator is ontwerp met 'n frekwensie toleransie van kleiner en gelyk aan ± 0.003 % wanneer dit ingestem word sender die nodige RF toerusting. 'n Ekonomiese wyeband - seingenerator is gemplementeer met 'n 74ACT14 logiese vlokkie om as 'n RF - bron gebruik te word om die ontvanger in te stel. Die boonste (hoer) harmoniek van die 4 kHz vierkantsgolf word as 'n "RF bron" gebruik. 'n Klankkaart is suksesvol gebruik as 'n modem om 1200 baud AFSK data (AX.25 protokol) te ontvang en die data met die nodige sagteware op 'n skerm te vertoon. Data is uitgcstuur vanaf 'n ander grondstasie.

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: After SUNSAT was launched in 1999 and the possibility of developing another micro satellite emerged, areas of possible improvement were identified. Among the suggestions that emerged was the idea of developing an on-board computer for a micro satellite, using one of the new generation low power processors. The processor had to meet guideline specifications derived from the experience gained by researchers and students involved with the SUNSAT project. This thesis covers the process of choosing one of these processors and the subsequent testing of the feasibility of using it in an on-board computer. The feasibility test included comparing the processor's specifications to those required and designing an evaluation board for this processor to test its ease of use and programmability. / AFRIKAANSE OPSOMMING: Nadat SUNSAT in 1999 gelanseer is en die moontlikheid vir die ontwikkeling van In soortgelyke satellite ontstaan het, is areas vir verbetering op bestaande stelsels geidentifiseer. Die idee om In nuwe generasie verwerker met lae kragverbruik as In aanboord rekenaar te gebruik, was een moontlikheid wat ondersoek moes word. Die verwerker moes aan riglyne gemeet, word wat afgelei is uit die ondervinding wat deur navorsers en studente tydens die SUNSAT projek opgedoen is. Die tesis dek die proses wat gevolg is om In verwerker te kies en die daaropvolgende toetsing om die bruikbaarheid van die verwerker as In aanboord rekenaar te bepaal. As deel van die toetsing is die verwerker se spesifikasies teen die verlangde spesifikasies opgeweeg, en In evaluasiebord is ontwikkel om die gemaklikheid van die gebruik en programmering van die verwerker te bepaal.

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This thesis describes various software technologies implemented, or specifically developed, for the SUNSAT micro-satellite mission. With the discussion centered on the Mission Operations System functions of Data Handling and Mission Control, particular emphasis is placed on data processing aspects such as the deployed database schema, and the data communications mechanisms implemented as part of the communications protocol stack. Both the groundsystem architecture and the Flight Software are discussed, their constituent components are analysed, and recommendations are made for improvement. Finally, a Unified Information Model for the design and operation of future, integrated satellite groundsystems is proposed, with suitable implementation technologies being identified and introduced. / AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die sagteware tegnologieë wat qeirnpternenteer. of spesifiek ontwerp is vir die SUNSAT mikro-satelliet missie, Met die bespreking gefokus op die Missie Operasionele Stelsel funksies van Data Hantering en Missie Beheer, word daar veral klem gelê op data prosesserings aspekte, soos byvoorbeeld die databasis skema wat ontplooi is, asook die data kommunikasie meganismes wat qeimplernenteer is as deel van die kommunikasie protokol stapel. Beide die grondstelsel argitektuur en die Vlugsagteware word bespreek, hulonderskeie komponente word geanaliseer, en aanbevelings ter verbetering word gemaak, Laastens word daar 'n Verenigde Informasie Model voorgestel vir die ontwerp en operasionele werking van 'n toekomstige, qeinteqreerde satelliet grondstelsel. Geskikte tegnologieë vir die implementasie hiervan word ook qeidentifiseer en voorgelê,