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.

Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / Conventional immunity tests are both time consuming and costly. There is thus a reasonable interest in relatively quick, but accurate and cost effective, in-house pre-compliance test techniques within an engineering design-house. This thesis provides information on the equivalence between in-house and conventional immunity test techniques. Three techniques were evaluated, namely: 1. E-field radiation with a log periodic antenna (conventional test technique); 2 E-field radiation with an inhouse designed and constructed modified TEM cell (in-house test technique); 3. Current injection using a complete off the shelf EMCO current probe device (in-house test technique). After the transfer data of the EMCO probe was verified, the modified TEM cell design, construction and equivalent measurement tests were performed. These tests revealed that within the respective bandwidth of interest, the devices produced results that are equivalent to each other within 0.9dB. Hence equivalence between in-house and conventional test techniques is possible.

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.

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.

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.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Structure from Motion suggests that an object or scene’s three-dimensional structure can be determined from its observed two-dimensional motion. Human efforts, manifested in computer algorithms, try to mimic the enormous power of the visual processing capabilities of the human brain. We present an algorithm to estimate structure, using the Unscented Kalman Filter, from the motion of point-wise features, produced by the Kanade-Lucas-Tomasi feature tracker. The algorithm is evaluated critically against an extensive set of motion sequences, with special attention paid to facial feature reconstruction.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / High-temperature superconductive (HTS) logic has become a large research field worldwide. The HTS advantages compared to the low-temperature circuits are the reduced cooling requirements, increased or comparable operation speeds and the "ease" of manufacturing. The potential of HTS logic circuits is vast and surpassed by very few other technologies. However, before these circuits can reach the market, suitable simulation packages and fabrication processes have to be designed. The simulation of HTS Rapid Single Flux Quantum (RSFQ) circuits are performed at temperatures between 30 and 77 Kelvin. The noise sources in Josephson junctions (JJ’s) are investigated and incorporated into these simulations. The results show that it is possible to operate these circuits in this temperature range. An objective of this thesis is the fabrication of HTS step-edge JJ’s. A process to fabricate these junctions was investigated and improved. This includes the etching of substrate steps with the use of the argon ion mill, deposition of the YBCO thin films with the Pulsed Laser Deposition (PLD) system and the etching of the final circuit by the use of dry or wet etching.

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.

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.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Visually estimating three-dimensional position, orientation and motion, between an observer and a target, is an important problem in computer vision. Solutions which compute threedimensional movement from two-dimensional intensity images, usually rely on stereoscopic vision. Some research has also been done in systems utilising a single (monocular) camera. This thesis investigates methods for estimating position and pose from monocular image sequences. The intended future application is of visual tracking between satellites flying in close formation. The ideas explored in this thesis build on methods developed for use in camera calibration, and structure from motion (SfM). All these methods rely heavily on the use of different variations of the Kalman Filter. After describing the problem from a mathematical perspective we develop different approaches to solving the estimation problem. The different approaches are successfully tested on simulated as well as real-world image sequences, and their performance analysed.