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Development of an experimental tilt-wing VTOL unmanned aerial vehicleVenter, Jacob 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / This project was initiated by ARMSCOR to research the feasibility of an unmanned
aerial vehicle launching from and landing on a South African Navy ship. The objective
of this project was to develop a strong basis for other similar projects.
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Video camera design and implementation for telemedicine applicationBehaimanot, Kibreab Ghebrehiwet 04 1900 (has links)
Thesis (MScIng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Primary health care telemedicine services require the acquisition and transmission
of patient data including high quality still and video images via telecommunication
networks.
The objective of this thesis is to investigate the implementation of a generalpurpose
medical camera as an alternative to the complex and costly CCD based
cameras generally in use at present. The design is based on FillFactory’s SXGA
(1280 ×1024) CMOS image sensor.
A low-cost Altera Cyclone FPGA is used for signal interfacing, filtering and colour
processing to enhance image quality.
A Cypress USB 2.0 interface chip is employed to isochronously transfer video
data up to a maximum rate of 23.04 MBytes per second to the PC.
A detailed design and video image results are presented and discussed; however
the camera will need repackaging and an approval for medical application by medical
specialists and concerned bodies before releasing it as full-fledged product. / AFRIKAANSE OPSOMMING: Primêre gesondheidssorg telemedisyne dienste moet hoëkwaliteit televisiebeelde
van hul pasiënte verkry deur van telekommunikasienetwerke gebruik te maak.
Die doel van hierdie tesis is om die toepassing van n meerdoelige mediese kamera
te ondersoek as n alternatief tot duur, komplekse CCD-gebaseerde kameras
wat huidiglik gebruik word. Die ontwerp is gebaseer op n hoëkwaliteit CMOS
beeldsensor.
n Goedkoop Altera Cyclone FPGA word gebruik vir seinkoppelvlak, filtering en
kleurprosessering om die kwaliteit van die beeld te verhoog.
n Hoëspoed USB 2.0 poort word gebruik om die data teen die nodige spoed te
versend.
n Gedetailleerde ontwerp, en die beeldresultate word voorgelê en bespreek. Die
kamera moet egter eers deur mediese spesialiste en relevante beheerliggame goedgekeur
word voordat dit as n volledige produk vrygestel kan word.
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Microwave heating of multiphase materials : modelling and measurementLouw, Willem J. 12 1900 (has links)
Thesis (MScIng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Both coaxial probe and waveguide (WG) measurement systems for electric and magnetic
material property extraction were investigated. These measurement techniques were used
to determine electrical properties of an inhomogeneous rock sample in its solid and
crushed states. A lumped element model of the probe was used and permittivity was
determined by the inversion algorithm developed by Stuchly and Stuchly. To support this
technique it was compared to a full wave inversion algorithm and referenced to properties
of the same samples but determined by a resonant cavity technique. The Nicholson, Ross
and Weir inversion algorithm was used to determine material properties from WG
measurements. As a reference, the same techniques were applied to a well defined
material. It was found that neither of the measurement techniques could measure low loss
factors or conductive materials and literature values were used in these cases. Various
simulation models of the multiphase ore in both its solid and crushed states are presented.
These models were utilised in finite-difference time-domain (FDTD) simulations of
different microwave (MW) cavities. Simulation and experimental S-parameter
comparisons are presented. The level of accuracy achieved varies as a function of the
geometrical representation and material properties. After an S-parameter comparison with
simulation results it was concluded that the electrical properties of both the solid and
crushed rocks have been well determined for MW cavity design. Predicted and measured
field distributions in cavities were also compared and it is shown that accurate models of
multiphase materials become especially important in the determination of field
distributions in and around different rock phases. Recommendations for the suggested
material property determination and verification processes are presented. A specific
application of this work is in the field of microwave assisted comminution. / AFRIKAANSE OPSOMMING: ’n Koaksiale probe en golfgeleier (WG) stelsels vir die bepaling van materiaal eienskappe
(elektries en magneties) word gebruik met die doel om ’n nie-homogene rotsmonster te
karakteriseer. Die ekstraksie algoritme van Stuchly en Stuchly word gebruik om die
materiaal eienskappe te bepaal vanaf die gemete S11-parameter. Hierdie ekstraksie
metode word vergelyk met ’n vol golf ekstraksie van permitiwiteit vanaf dieselfde
gemete data. Beide die ekstraksie metodes word dan vergelyk met resonante holte
meetings van dieselfde materiale. Die Nicholson, Ross en Weir ekstraksie algoritme word
toegepas op meetings wat gedoen is deur die golfgeleier stelsel. As ’n verwysing word
dieselfde tegnieke toegepas op ’n bekende materiaal en daar is gevind dit stem goed
ooreen behalwe dat nie een van die twee meet tegnieke lae verlies faktore kan meet nie.
Verder kan nie een van die twee sisteme geleidende materiale meet nie. Vir sulke gevalle
is waardes nageslaan. Verskeie simulasiemodelle van die rots word voorgestel vir beide
soliede en vergruisde monsters.
Hierdie modelle word gebruik in FDTD simulasies van verskeie mikrogolftoevoegers met
die oog om ’n vergelyking te tref tussen gesimuleerde en gemete S-parameters.
Verskillende vlakke van akkuraatheid is bereik en is ’n funksie van die geometrie en die
materiaaleienskappe van die model. Nadat gemete en gesimuleerde S-parameters
vergelyk is, is gevind dat die materiaal eienskappe van beide die soliede en vergruisde
rots monsters goed bepaal is vir mikrogo lf toevoeger ontwerp. Voorspelde en gemete
veldverspreidings word ook vergelyk en dit is veral hierso van belang om ’n realistiese
model van die nie-homogene monster te gebruik. Sekere voorstelle word gemaak om die
verskillende aspekte van die meet van ma teriaaleienskappe en simulasiemodelle te kan
verfyn. ’n Spesifieke toepassing van hierdie werk is in mikrogolf ondersteunde skeiding
van minerale en erts.
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Upgrading of a radar system to implement a firmware based pulse compressorRust, Johannes Stephanus Warnich 03 1900 (has links)
Thesis (MScIng)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: This project investigates the improvement of an existing radar system by means of currently available technologies
and signal processing techniques. Upgrades are aimed to improve the system's speci cations with focus on
range resolution. Pulse compression and Doppler processing techniques are used to accomplish the improvement
in range resolution. The use of pulse compression however resulted in numerous modi cations to the RF
sub-system required by the introduction of Direct Digital Synthesizer modules. A full replacement of the existing
signal processor with a Doppler processing based signal processor implemented on a single programmable
rmware device was designed. Certain sections of this signal processor were implemented and tested. Pulse
compression was successfully implemented and tested in both the transceiver and signals processor sections. / AFRIKAANSE OPSOMMING: Hierdie projek ondersoek die verbetering van 'n bestaande radar stelsel deur gebruik te maak van huidige
tegnologie en seinverwerking tegnieke. Aanpasings is gemik om die radarstelselspesi kasies te verbeter met die
fokus op afstandsresolusie. Pulskompressie en Doppler- lter tegnieke is gebruik om 'n verbetering te maak
aan die afstandsresolusie van die stelsel. Die gebruik van pulskompressie het 'n groot aantal veranderings
aan die RF-stelsel genoodsaak a.g.v. die gebruik van Direkte Digitale Sintetiseerder modules. Die huidige
radarseinverwerker is volledig vervang met 'n Doppler gebaseerde verwerker. Hierdie verwerker is volledig
ontwerp op 'n enkele programmeerbare fermatuureenheid maar slegs sekere gedeeltes is getoets. Pulskompressie
is suksesvol toegepas en getoets in beide die RF-stelsel en in die gedeeltes van die radarseinverwerker wat getoets
is.
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Rapid single flux quantum very large scale integrationGross, Peter Alan 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Very Large Scale Integration (VLSI) of the Rapid Single Flux Quantum (RSFQ)
superconducting logic family is researched. Insight into the design methodologies used
for large-scale digital systems and related logistics are reviewed. A brief overview of
basic RSFQ logic gates with in mind their application in a cell based layout scheme
suited for RSFQ is given. A standard cell model is then proposed, incorporating these
cells, on which, a library of low temperature superconducting (L TS) cells are laid out.
Research is made into computer techniques for storing and manipulating large-scale
circuit netlists. On this base, a method of technology mapping Boolean circuits to an
RSFQ equivalent is achieved. Placements on-chip are made, optimized for minimum net
length, routed and exported to a popular electronic mask format. Finally, the convergent
technology fields of solid state cooling and high-temperature superconducting electronics
(HTS) are investigated. This leads to a proposal for a low profile, low cost, HTS
cryopackaging concept. / AFRIKAANSE OPSOMMING: Grootskaalse integrasie (VLSI) van die "Rapid Single Flux Quantum" (RSFQ)
supergeleidende familie van logiese hekke word uiteengesit. Insig in die ontwerpmetodes
vir grootskaaIse digitale stelsels en verwante aspekte word ondersoek. 'n Kort oorsig van
basiese RSFQ logiese hekke word gegee, met hulle toepassing in 'n uitlegskema wat
geskik is vir RSFQ. 'n Standaard sel model, wat bogenoemde selle insluit, word
voorgestel en 'n selbiblioteek word uitgele vir lae temperatuur supergeleidende bane.
Ondersoek word ingestel na die manipulasie van die beskrywing van elektroniese bane en
'n manier om logiese Boolese baanbeskrywings om te skakel na fisiese RSFQ bane. Die
fisiese plasing van selle word bespreek ten einde die verbindingslengte tussen selle te
minimeer. Die finale uitleg word omgeskakel na 'n staandaard elektroniese formaat vir
baanuitlegte. Die konvergerende tegnologievelde van "soliede toestand" verkoeling en
hoe-temperatuur supergeleidende elektroniese bane word bespreek. Ten slotte word 'n
nuwe tipe, lae profiel en lae koste kriogeniese verpakking voorgestel.
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A dual circularly polarized single element microstrip patch antennaMaki, Pamela Ruth 03 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: This thesis discusses the design of a dual circularly polarized single element antenna with special
emphasis on achieving a wide bandwidth and high polarization isolation. The aim of the study is to
produce an antenna for transmission of colour video signals between a ground station and a low
earth orbit satellite.
Microstrip patch antennas are suitable for satellite applications because they are light weight,
conformal and have a thin profile. However, the antennas' inherent naITOW bandwidth is one of
their major drawbacks. The aperture coupled microstrip patch antenna boasts of a much-improved
bandwidth over the traditional single layer microstrip antenna and the freedom of using separate
substrates for the patch and the feeding network. Hence the designed single element antenna is
aperture coupled. To achieve dual circular polarization with good polarization purity, the antenna
had a crossed slot aperture with a balanced feed. The feed network was designed on a single layer.
The design was executed in two steps using IE3D moment of methods simulation software: design
of the radiating part, and design of the feed part. Each part was simulated and optimized on its own
before the two were combined, simulated and optimized again. Parameters used in the antenna
optimization were: the substrates' thicknesses and dielectric constants, patch and aperture
dimensions, and the feed line width and offset.
The designed antenna was built and measured. Initial measurements of S-parameters yielded
unacceptable results, especially for S22 and S21, and so an investigation into the matter was
conducted. That led to the sizes of the feed and reflector planes being extended. Absorbing material
was used between the parallel feed and reflector planes because some power was, to a lesser extent,
still escaping, due to the fact that the planes were fmite.
Measurement results demonstrated reasonable agreement with the simulation. The final antenna had
a reflection coefficient of less than -10 dB for the entire operating band of 400 MHz centred on 3
GHz, an isolation of approximately -15 dB in the operating band and a gain of 2 dBi and I dBi for
Ports 1 and 2, respectively, at 3 GHz. These results, especially the gain, are influenced by the back
radiation and the finite sizes of the feed and reflector planes. It is therefore recommended that an
enclosed cavity be used at the back of the antenna and a 'dogbone' aperture be used to minimize
back radiation. / AFRIKAANSE OPSOMMING: Die tesis omskryf die ontwerp van 'n tweevoudige sikuler gepolariseerde enkel-element antenne
met spesiale klem op wye bandwydte en hoe polariserings isolasie. Die doel van hierdie studie is
om 'n antenne vir uitsending van kleur video seine tussen 'n grond stasie en 'n omnentelingsatelliet
daar te stel.
Mikrostrook plakantennes is gepas vir satelliet toepassings weens hulle ligte gewig en dun profiel.
Die antenne se gepaardgaande nou bandwydte is egter een van hulle grootste nadele. Die
gleufgekoppelde mikrostrook plakantenne gee egter 'n baie beter bandwydte as die tradisionele
enkellaag mikrostrook plakantenne asook die vryheid om verskillende substrate vir die plak en die
voernetwerkte gebruik. Vir hierdie redes daar besluit om die enkel-element antenne sleufgekoppeld
te maak. Om tweevoudige sikuler gepolariseerde met goeie polarisasie suiwerheid te kry, moes 'n
kruisvonnige gleuf met 'n gebalanseerde voer ontwerp word. Die voernetwerk was op 'n enkellaag
ontwerp.
Die ontwerp was in twee fases in IE3D momentmetode simulasie sagteware gedoen: ontwerp van
die stralings gedeelte, en ontwerp van die voer gedeelte. Elke gedeelte word afsonderlik gesimuleer
en geoptimiseer voordat die twee saam gesimuleer en geoptimiseer word. Parameters wat gebruik
word in die antenne optimiseering is: dikte van substraat en dielektriese konstante, plak en gleuf
grootes, en voer lynwydte en afwyking.
Die ontwerpde antenne is gebou en gemeet. Aanvanklike metings van S-parameters het
onaanvaarbare resultate gel ewer, vera I vir S22 en S21,dus is daar besluit om die redes daarvoor te
ondersoek. Dit het daartoe gelei dat die voer- en reflector vlakte groter gemmak is. Absorbeer
material is tussen die parallel voer- en reflector vlakke gebruik aangesien steeds drywing verloor is
weens die eindige vlakke.
Meting resultate het taarnlike goed met die simulasies vertoon. Die finale antenne het 'n
weerkaatskoeffisient laer as -10 dB getoon vir die volle bandwydte van 400 MHz gesentreerd
rondom 3 GHz, 'n isolasie van ongeveer -15 dB in die bandwydte en 'n aanwins van 2 dBi en I dBi
vir onderskeidelik Poorte I en 2 by 3 GHz. Hierdie resultate veral die aanwins is deur die straling
na agter beinvloed en die eindige grootes van die voer- en reflector vlakke. Dit word om hierdie
rede dus voorgestel dat 'n geslote holte aan die rugkant van die antenne gebruik word en dat 'n
"dogbone" gleuf gebruik word om straling na agter te minimeer.
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Design and analysis of broadband microwave PIN diode switchesEngelbrecht, Quintin 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The aim of this thesis is the analysis and design of a broadband PIN diode switch.
Pin diode switches are gaining popularity in RF and microwave applications today. This is due
to their excellent switching and power handling capabilities, reliability, low cost and small size.
An analysis and design procedure for broadband PIN diode switch design, using the series,
shunt and compound topologies respectively, is presented.
In order to do a proper switch design, accurate practical models for the components are
required. Parameter extraction therefore formed an important consideration for this study. A
parameter extraction procedure is presented, which enables the designer to very accurately
extract the required models for the components in the environment they operate in. The
designer can then do a proper design to ensure that the switch response when measured, closely
corresponds to that simulated.
A compound configuration switch was designed, built and measured to confirm the validity of
the design procedure. The results illustrate that if the extracted models of the components are
integrated into the design, the measured and simulated response compare remarkably well. / AFRIKAANSE OPSOMMING: Die doel van die tesis is die analise en ontwerp van 'n wyeband PIN diode skakelaar.
PIN diode skakelaars is besig om meer populariteit te verwerf in hedendaagse RF en mikrogolf
toepassings. Dit is as gevolg van die diode se goeie skakel- en drywing hantering vermoëns,
betroubaarheid, lae koste en klein fisiese dimensies. 'n Analise en ontwerpsprosedure vir wye
band PIN diode skakelaars in die serie, parallel en saamgestelde topologieë word getoon.
Om 'n deeglike skakelaar ontwerp te doen, word akkurate en praktiese modele van die
komponente benodig. Parameter ekstraksie was daarom 'n groot oorweging vir hierdie studie.
'n Metode om parameters te onttrek word getoon wat die ontwerper in staat stelom akkurate
modelle van komponente te onttrek, in die omgewing waarin hulle gebruik word. Die
ontwerper kan dan 'n deeglike ontwerp doen wat as dit gemeet word.. die gemete en
gesimuleerde resultate goed salooreenstem.
'n Saamgestelde topologie skakelaar is ontwerp, gebou en gemeet om die ontwerpsprosedure te
verifieer. Die resultate toon dat as die modelle wat onttrek is, gebruik word in die ontwerp, dan
stem die gemete en gesimuleerde resultate baie goed ooreen.
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Development and implementation of a modbus based wireless air protocolRamalata, Mulalo Phillip 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The recent performance improvements of wireless communication systems are presenting
possibilites for the use of wireless networks for industrial applications, which typically
impose severe restrictions in terms of response time and flexibility.
Traditionally most of the industrial protocols employ cable connections, which have limitations
in terms of flexibility and development oportunities. The industrial protocol used
for this project, is the Modbus protocol. This protocol is developed and implemented on a
wireless environment by using data radio modems. The Modbus protocol is a master/slave
protocol which provides an industry standard for industrial data transfer.
A Modbus driver is designed for radio networks, so that it can function with different
PLCs and SCADA packages, supporting Modbus protocol. This enables control and
monitoring to be excercised over a long distance, and enables control equipment to be
placed as required and not with particular wiring restrictions. / AFRIKAANSE OPSOMMING: Die onlangse verbetering in radiokommunikasiestelsels bied moontlikhede vir die gebruik
van radionetwerke vir industriële toepassings, wat gewoonlik streng beperkings plaas in
terme van responstyd en buigbaarheid. Tradisioneel is meeste van die industriële protokolle
kabelgebaseer, wat redelik onaanpasbaar is.
Die Modbus protokol is as basis in hierdie projek gebruik. Dit is 'n meester/slaaf industriestandaard,
wat hier aangepas is vir toepassings met radiomodems. Die Modbus drywer
is ontwerp om funksioneel te wees met 'n verskeidenheid van PLC's en SCADA pakette,
wat die Modbus protokolondersteun. Dit stel beheer- en meetaksies in staat oor lang
afstande en laat relatief vrye plasing toe van toerusting sonder bedradingsbeperkings.
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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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Software architecture design of a software defined radio systemCronje, Johannes Jacobus 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The high pace of technological advancement enables the realisation of ever more advanced
mobile communications standards with more functionality than simple voice
communications. The hardware that is used to implement the radio sections of these
systems generally require long design cycles, much longer than the design cycles of
the other components of a communications system. Another problem is that, once new
communications standards are introduced, the current hardware platforms used in the
terminal equipment becomes obsolete because they can generally not be used with the
new standards. This has serious cost implications for both the service provider and the
consumer, because both parties have to acquire new equipment to be able to use the
new standards.
An elegant solution to the above issues is to use software-defined radio sections to
replace the hardware radio components. New communications standards can then be
supported by simply loading new software onto the equipment, provided the maximum
processing capacity of the processor(s) that the software runs on can accommodate
the bandwidth requirements of that specific standard.
This thesis investigates the ideas behind software defined radio and also describes
the design and implementation of a software architecture that can be used to implement
software defined radios on general-purpose platforms such as personal computers. / AFRIKAANSE OPSOMMING: Die hoë tempo van tegnologiese vordering maak dit moontlik om baie gevorderde
mobiele kommunikasie standaarde te implementeer wat meer funksionaliteit bied as
blote spraakkommunikasie. Die hardeware wat gebruik word om die radios van
sulke stelsels te implementeer neem gewoonlik langer om te ontwikkel as die ander
komponente van die stelsels. Die ander probleem is dat hierdie hardeware gewoonlik
nie hergebruik kan word wanneer nuwe kommunikasie standaarde in gebruik geneem
word nie omdat die standaarde nie versoenbaar is nie. Dit het tot gevolg dat beide
die verbruiker en die diensverskaffer groot bedrae geld moet spandeer om die nuwe
tegnologie te kan gebruik.
'n Elegante oplossing vir hierdie probleme is om gebruik te maak van radios waarvan
die funksionaliteit in sagteware gedefiniëer word. Nuwe kommunikasie standaarde
kan dan gebruik word deur slegs die nodige sagteware op die toerusting te laai, solank
die verwerkingskapasiteit van die mikroverwerkers in die stelsel die benodigde bandwydte
kan akkommodeer.
Hierdie tesis ondersoek die konsepte van sagteware-gedefiniëerde radio en beskryf
die ontwerp en implementering van 'n sagteware argitektuur vir die implementering
van sagteware-gedefiniëerde radios op veeldoelige platforms soos persoonlike rekenaars.
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