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Development of dynamically reconfigurable ground station softwareMarais, Hendrik Gideon 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / Applications are normally developed with a specific purpose in mind and when
new features are needed the source code has to be modified, recompiled and
redistributed. It will be more beneficial if new features can be dynamically
added during runtime without the need to disrupt execution, especially in the
case of ground station software.
This thesis is about the implementation of a dynamic development environment
within which a modular system can be created from existing components
that can be extended with additional components at any time. The interaction
between these components can then be specified which can result in a
completely automated system.
It is concluded that the graphical tools of such an environment can make it
easy for people who do not necessarily have programming knowledge to build
a system from existing components that can be extended and reconfigured
whenever necessary.
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The design of a telemetry system for Grumeti reservesLabuschagne, Adriaan S. 03 1900 (has links)
Thesis (MScEng (Electrial and Electronic Engineering.))--University of Stellenbosch, 2006. / This thesis covers the design and development of a radio telemetry system
to assist in management of the Grumeti reserves. This was accomplished
through the integration of a digital data transmission system into the existing
analog voice radio network, while minimizing any possible interference.
The primary application of the system is vehicle tracking, but it is also capable
of supporting other telemetry data in the future. The system relies on
a server based at the reserve headquarters and various client telemetry units
installed in the vehicles. A vehicle’s location is requested via the server application.
The results are displayed on a digital map and stored into a database.
Various methods are used to reduce radio interference and support reliable
transmission of data. The system is also designed to be affordable, maintainable
and robust. Two prototypes were implemented to perform various tests
and establish the feasibility of the sysem. It proved to be capable of meeting
the main objectives and implementation will commence in the future.
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An HMM-based automatic singing transcription platform for a sight-singing tutorKrige, Willie 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / A singing transcription system transforming acoustic input into MIDI note sequences
is presented. The transcription system is incorporated into a pronunciation-independent
sight-singing tutor system, which provides note-level feedback on the accuracy with which
each note in a sequence has been sung.
Notes are individually modeled with hidden Markov models (HMMs) using untuned
pitch and delta-pitch as feature vectors. A database consisting of annotated passages
sung by 26 soprano subjects was compiled for the development of the system, since no
existing data was available. Various techniques that allow efficient use of a limited dataset
are proposed and evaluated. Several HMM topologies are also compared, in analogy with
approaches often used in the field of automatic speech recognition. Context-independent
note models are evaluated first, followed by the use of explicit transition models to better
identify boundaries between notes. A non-repetitive grammar is used to reduce the
number of insertions. Context-dependent note models are then introduced, followed by
context-dependent transition models. The aim in introducing context-dependency is to
improve transition region modeling, which in turn should increase note transcription accuracy,
but also improve the time-alignment of the notes and the transition regions. The
final system is found to be able to transcribe sung passages with around 86% accuracy.
Finally, a note-level sight-singing tutor system based on the singing transcription system
is presented and a number of note sequence scoring approaches are evaluated.
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Satellite data transmission by means of a multi-channel systemSmith, David 12 1900 (has links)
Thesis (MEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / The aim of this thesis is to find an a ordable and upgradeable manner of increasing the data
rate of current satellite systems. The compression, modulation and amplification techniques and
telecommunication regulations restrict the data rate, which are bypassed by designing a parallel
channel configuration.
In order to test this solution a system is developed that is based on the existing standards of
DVB-S and MPEG-2. The combination of these standards protect the data from interference,
package the data for ease of storage, modulate the data to more effectively radiate the signal and
shape the spectrum to adhere to telecommunication regulations.
The spacing between the channels is reduced and the transmitted signal is amplified to inject interference
into the system. The effect of this interference on the receiver is shown by transmitting
image data and comparing the received image with the original.
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USB telephony interface device for speech recognition applicationsMuller, J. J. 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Automatic speech recognition (ASR) systems are an attractive means for companies to deliver value added
services with which to improve customer satisfaction. Such ASR systems require a telephony interface to
connect the speech recognition application to the telephone system. Commercially available telephony
interfaces are usually operating system specific, and therefore hardware device driver issues complicate the
development of software applications for different platforms that require telephony access. The drivers and
application programming interface (API) for telephony interfaces are often available only for the Microsoft
Windows operating systems. This poses a problem, as many of the software tools used for speech recognition
research and development operate only on Linux-based computers. These interfaces are also typically in
PCI/ISA card format, which hinders physical portability of the device to another computer. A simple, cheaper
and easier to use USB telephony interface device, offering cross-platform portability, was developed and
presented, together with the necessary API.
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The development of a dynamically configured wireless ad-hoc multihop network protocolPretorius, Wynand 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / An ad-hoc network encompasses the cooperative engagement of a collection
of mobile nodes that are free to move and communicate with each other
wirelessly without the required intervention of any centralized access point
or existing infrastructure.
The advantage of such a network lies in it’s robustness, adaptiveness, the
fact that its self-configurable and that it becomes somewhat indestructible
due to it’s decentralized nature. But such a network layout simultaneously
introduces many complex network management issues which are normally
taken care of inherently by a rigid network architecture.
The biggest challenge faced by any such protocol is the fact that it needs
to be scalable, must maintain a decent stable data throughput, all whilst
performing it’s own continuous network management and associated routing
algorithms.
These mobile nodes need a complex, scalable, compact and essentially realtime
algorithm for maintaining an up to date representation of the overall
network layout, yet without clogging the system’s communications channels
with too much overhead traffic, and drastically lowering the effective data
throughput.
Since each mobile node only has a limited communications range each node
also needs very advanced routing capabilities which will allow it to track who
is currently within communications range, and at the same time allow the
node to create multihop paths to distant destination nodes, thus connecting
nodes which cannot directly communicate.
This report follows the development process of both the software needed
to successfully conceptualize, simulate and test the protocol, as well as the
hardware needed as proof of concept. It highlights and discusses the various
design choices / considerations made in development of such a protocol,
the strong- and weakpoints of the developed protocol, as well as providing
several possibilities to further evolve the developed protocol.
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The design of a hysteroscopy simulatorKruger, Gerrit V. 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / This thesis documents the research, design and implementation of a virtual
hysteroscopy simulator. A hysteroscopy is a medical procedure used in the
field of obstetrics and gynaecology. The system consists of a mechanically
modelled hysteroscope connecting to any personal computer using USB, and
is plug and play compatible on any modernWindows operating system. The
scope interfaces with custom-designed software, which simulates a patient’s
anatomy and thus creates a virtual operating environment. The software
incorporates features like simulated soft tissue and an ablation algorithm.
This system is developed with the aim to aid the young or inexperienced
surgeon with hands-on training, developing his hand-eye coordination and
visual and surgical skills used in this procedure.
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The dynamic modelling and control system of a tethered aerostat for remote sensing applicationsFourie, Daniel Andries 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Aerostats and Stratolites could play a major role in expanding current satellite and other technologies
in the near future. A study was made on the development of aerostat platforms and the current
state of Stratolite development.
The aim was to develop an airship system that is capable of maintaining a specific position
regardless of the presence of wind. The various applications of such a geostationary platform are
discussed.
A dynamic model of an airship was developed and a simulation was implemented in software.
This was done to study the possibility of developing aerostats like these.
A tethered airship system was developed and built to demonstrate that it is possible to control
the position of an airship. The airship system uses current technology in an unique combination to
fulfil the requirement of remaining stationary despite the influence of wind.
Various control system design techniques were used to implement the controllers. Linear models
of the airship system were identified practically and used to design the controllers.
The controllers were tested in simulation as well as practically and the results of these tests
are given. It was concluded that there exists potential for the development of Stratolite systems,
although there exists a fair amount of challenges and obstacles that would need to be overcome
before this technology could be implemented. / AFRIKAANSE OPSOMMING: Aerostats en Stratolites kan ’n besondere rol speel in die uitbreiding van huidige sateliet- en ander
aardwaarnemingstoepassings. ’n Studie is gemaak oor die ontwikkeling van Aerostat platforms en
die huidige stand van Stratolite ontwikkeling.
Die mikpunt was om ’n lugskipstelsel te ontwikkel wat in staat is om ’n spesifieke posisie te
handhaaf ten spyte van die invloed van wind. Die verskeidenheid van toepassings, waarvoor so ’n
geostasionêre platform gebruik kan word, word genoem.
’n Dinamiese model van ’n lugskip is ontwikkel en die stelsel is in sagteware gesimuleer. Dit is
gedoen om die moontlikheid te ondersoek om sulke Aerostats in die toekoms te ontwikkel.
’n Lugskipstelsel, wat aan die grond geanker word met ’n kabel, is ontwerp en gebou. Die stelsel
is gedemonstreer en daar is bewys dat dit moontlik is om die posisie van die lugskip te beheer. Die
lugskip gebruik huidige tegnologie wat in ’n unieke kombinasie saamgevoeg is om te illustreer dat
dit moontlik is vir die lugskip om stasionêr te bly ten spyte van wind.
Verskeie beheerstelsels ontwerptegnieke is gebruik om die beheerders mee te implementeer. Lineêre
modelle van die lugskip is prakties geïdentifiseer en is gebruik om die beheerders te ontwerp.
Die lugskip se beheerders is in simulasie sowel as prakties getoets en die resultate van hierdie
toetse word gegee. Die projek bevestig dat daar ’n potensiaal bestaan vir die praktiese ontwikkeling
van Stratolite stelsels. Daar is egter ’n hele paar uitdagings en probleme wat eers uit die weg geruim
sal moet word, voordat hierdie tegnologie ’n alledaagse werklikheid sal word.
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The instrumentation and initial analysis of the short-term control and stability derivatives of an ASK-I3 gliderBrowne, Keith R.J. 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2004.
220 leaves single printed pages ,preliminary pages i-xiv and numberd pages 1-188.Includes bibliography.list of figures and used a Hp Scanjet 8250 Scanner to pdf format (OCR), / ENGLISH ABSTRACT: This thesis describes the process followed to determine the short-term control and stability
derivatives of an ASK-13 glider (ZS-GHB). The short-term control and stability derivatives are
obtained by parameter estimation done using data recorded in flight. The algorithm used is the
MMLE3 implementation of a maximum likelihood estimator.
To collect the flight data sensors were installed in the ZS-GHB. Sensors measuring the
control surface deflections, translation acceleration, angular rates and the dynamic and static
pressure are needed to provide enough data for the estimation. To estimate accurate derivatives
specific manoeuvres were flown by the pilot, to ensure that all the modes of the glider were
stimulated.
The results reveal that the control and stability derivatives estimated from the flight data are
not very accurate but are still suitable to be used in simulating the glider's motion. / AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die proses wat gebruik is om die kort periode beheer en stabiliteit afgeleides
van 'n ASK-13 sweeftuig vas te stel. Die kort periode beheer en stabiliteit afgeleides is
verkry deur parameter afskatting op data wat gedurend vlugte van die sweeftuig opgeneem is.
Die algoritme wat gebruik is om die parameters af te skat is die MMLE3 voorstelling van 'n
maksimale moontlikheid afskatter.
Om vlug data te versamel sensore moes in die sweeftuig geinstalleer word. Die sensore meet
beheer oppervlak hoeke, versnellings, hoeksnellhede en die dinamies en statiese lugdruk om te
verseker dat daar genoeg data is vir die afskatting. Om die afgeskatte parameters akkuraad te
kry moet die loods spesefieke manoeuvres vlieg om seker te maak dat al die moduse van die
sweeftuig is gestimuleer.
Die resultate wat gelewer is 'n stel kort periode beheer en stabiliteit afgeleides wat nie
akkuraad is nie, maar wat weI goed genoeg is or ie bewegings van die sweeftuig te simuleer.
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The design of a high speed topology for a QPSK demodulator with emphasis on the synchronization algorithms needed for demodulationBooysen, Samuel 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This thesis describes the design and implementation of a software based QPSK demodulator
with a demodulation speed of 100 Mbps. The objective of the thesis was to identify a topology
for the QPSK demodulator that would allow for high data rates and the design of the synchronization
algorithms for carrier and symbol recovery. The QPSK demodulator was implemented
on an Altera Stratix II field programmable gate array (FPGA), which does complex I and Q sampling
on a down converted 720 MHz QPSK signal. The I and Q down converted baseband
signals are sent through matched filters which are implemented with discrete components to
maximize the signal to noise ratio of the received rectangular baseband pulses. A 1 GSPS direct
digital synthesizer (DDS) is used to generate the synchronous clock for the analog to digital
converters which samples the matched filter outputs. The demodulator uses two samples per
symbol to demodulate the QPSK signal. A dual locking system is implemented to have a wide
pre-locking filter for symbol synchronization and a narrow band post-lock filter to minimize the
loop noise. A symbol lock detection algorithm decides when the symbol recovery loop is locked
and switches between the loop filters.
A second 1 GSPS DDS output is mixed with a local oscillator to generate the 1.44 GHz LO signal
for the quadrature down conversion. The carrier recovery loop uses a numerically controlled oscillator
inside the FPGA for initial carrier acquisition which allows for very wide locking bandwidth.
After lock is achieved, the external carrier recovery loop takes over and removes any
frequency offset in the complex baseband signal by changing the frequency of the DDS. A QPSK
modulator was also developed to provide a QPSK signal with known data. The modulator can
generate any constellation diagram up to 256 points. / AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die ontwerp en implementasie van ’n sagteware gebaseerde QPSK demodulator
met ’n demodulasie spoed van 100 Mbps. Die doelstelling is om ’n topologie te identifiseer
vir ’n QPSK demodulator wat ’n hoë datatempo sal toelaat en ook om sinkronisasie algoritmes
te ontwikkel vir draer en simbool herkenning.
Die QPSK demodulator is geïmplimenteer op ’n Stratix II FPGA van Altera wat kompleks basisband
monstering doen op infase en kwadratuur basisband seine. Die basisband seine word
gegenereer van ’n 720 MHz QPSK sein met ’n kwadratuur menger wiese uittrees deur puls
passende filters gestuur word om die sein tot ruis verhouding te maksimeer. ’n Een gigamonster
per sekonde direk digitale sintetiseerder (DDS) is gebruik om die klok vir die analoog na digitaal
omsetters te genereer vir sinkrone monstering van die pulse passende filter uittrees. Die demodulator
gebruik twee monsters per simbool om ’n QPSK sein te demoduleer. ’n Tweevoudige sluit
algoritme word gebruik vir die simbool sinkronisasie waar ’n wyeband filter die inisiële sluit
funksie verrig en dan word daar oorgeslaan na ’n nouband filter vir fase volging wat die ruis
in die terugvoerlus verminder. Daar is ’n simbool sluit detektor wat identifiseer wanneer die
simbool beheerlus gesluit is en selekteer dan die gepaste filter.
’n Tweede DDS en ’n sintetiseerder se uittrees word gemeng om ’n 1.44 GHz draer te genereer
vir kohurente frekwensie translasie in die kwadratuur menger. Die draer sinkronisasie gebruik
’n numeries beheerbare ossilator vir die inisiële frekwensie en fase sluit wat baie vinnig geimplenteer
kan word omdat dit alles in sagteware binne in die FPGA gebeur. Na die interne draer
beheerlus gesluit is, neem die eksterne beheerlus oor om enige fase of frekwensie afsette in die
kompleks basisband seine van die kwadratuur menger te verwyder deur die frekwensie van
die draer DDS te beheer. ’n QPSK modulator is ook ontwikkel om verwysings data te genereer.
Enige konstelasie vorm tot 256 punte kan geimplementeer word.
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