Abstracts of MSc Theses: 2003


List of MSc Theses: 2003

  1. Thomas G H Bennett Development of a Parallel SAR Processor on a Beowulf Cluster.
  2. Michael K Cope Design, Simulation and Implementation of a Digital Quadrature Demodulator for a Stepped Frequency Radar.
  3. Tinashe Gwena Gollach: Configuration of a Cluster based Linux Virtual Server.
  4. Stephen Karabo Modise Development of a Real Time Radar Data Acquisition System.
  5. Teboho Nyareli Development of a Cable Odometer with a Network Interface.
  6. Daniel J Tanser Simulation of a Slope Stability Radar for Opencast Mining.

Back to list of Group's MSc Theses


Bennett T G H

Development of a Parallel SAR Processor on a Beowulf Cluster


The purpose of this dissertation is to present the development and testing of the parallelisation of a Range-Doppler SAR processor. The inherent data parallelism found in SAR data lead to the choice of using master slave parallel processor, where copies of a slave task perform the same tasks on different sets of data.

However, the SAR processor that was parallelised needed to implement a corner turn without saving data to disk keeping the data set being processed distributed in memory over the nodes in the cluster. This was successfully achieved using a in-place method, thus saving valuable memory resources.

Once the parallel processor was implemented some timing tests where performed, yeilding a maximum speedup factor of 6.2 for an 8 slave processor system.

Back to list of Group's MSc Theses


Cope M K

Design, Simulation and Implementation of a Digital Quadrature Demodulator for a Stepped Frequency Radar


This thesis describes the model used to investigate the effects of Phase Noise and Quantisation noise on the IF quadrature detector of a SFCW radar.

The scope of this thesis is the design and implementation of a digital quadrature demodulator for a stepped frequency ground penetrating radar. This dissertation presents a theoretical model of the demodulator, simulations characterising the demodulator performance, as well as the design, construction and measurement of the prototype demodulator.

The demodulator estimates the amplitude and phase of the intermediate frequency signal of a time-interleaved dual-channel heterodyne radar receiver. A demodulator model is developed from a survey of the relevant literature, paying particular attention to errors introduced in sampling. Simulations predict the demodulation performance in the radar system, suggesting coherent integration improves acuracy by reducing the effect of random sampling errors. The design of the prototype and characterisation of its performance are briefly reported.

Measurements confirmed that coherent integration increased the demodulator accuracy. Timing jitter was found to be the most significant cause of error, due to phase noise in the IF signal. The simulations predicted that the demodulator would not meet the specified performance; measurement determined the prototype's accuracy to be within specification, although the test signals were of higher quality than the expected radar IF signal.

Back to list of Group's MSc Theses


Gwena T

Gollach: Configuration of a Cluster based Linux Virtual Server


This dissertation discusses the configuration of the Gollach cluster. The system has a shared disk spread over all machines, and uses MOSIX to share load. All machines boot off a single server.

This thesis describes the Gollach cluster. The Gollach is an eight machine computing cluster that is aimed at being a general purpose computing resource for research purposes. This includes image processing and simulations. The main quest in this project is to create a cluster server that gives increased computational power ad a unified system image (at several levels) without requiring the users to learn specialised tricks. At the same time the cluster must not be tasking to administer.

The making of this cluster aims to give a single image on several levels of the computer, which are: processes, I/O (Input/Output) and storage. To achieve this the cluster computer is built together on a unified backbone that ensures sharing on the levels mentioned above. It makes use of diskless booting, NFS-root (Network File System), MOSIX and LVS (Linux Virtual Server) to achieve this. MOSIX migrates processes and balances load. LVS distributes users on the cluster server. Diskless booting and NFS-root file system ensure that all the machines on the cluster share a single disk image. Mass storage has been aggregated with the help of NBD (Network Block Device) and software RAID (Redundant Array of Independent Disks).

The Gollach has been built and it provides a general computing resourec for multiple users. Administration turns out to be at almost the same level as a single Linux server due to the use of ClusterNFS. ClusterNFS is an NFS server which provides name translation. Therefore machine specific files can be kept unique on the file server. User distribution using LVS has worked as expected, users' requests are always attached to the machine with the least connections. The mass storage device has been tested to work with RAID-0. The cluster has been made to run conventional programs as a conventional server, here it works to expectation with no visible difference to a single machine server. Parallelism with the help of MOSIX has been observed and non-I/O bound processes have experienced a speed-up due to the process migration. Disk I/O processes suffer though, from the speed descaling found with multiple simultaneous reads/writes.

Back to list of Group's MSc Theses


Modise S K

Development of a Real Time Radar Data Acquisition System


This thesis describes the implementation of the Geosonde software on a real time Linux platform. The hardware platform is a 486 system in PC104 format

The Geosonde radar system, developed for use in bore holes, includes a data acquisition system. Development is currently being conducted by the Radar Remote Sensing Group at the University of Cape Town and Stellenbosch University.

This thesis describes the development of a real time operating system and an overall upgrade of basic interfaces to the Geosonde system. The current system employs the use of an embedded MS-DOS operating system and supports basic user control and data exporting over serial line.

The objectives of this thesis are to perform major upgrades on the system by introducing an XML based form of network control and NTP synchronization of the processing board. As a result, an investigation into the adequacy of MS-DOS as a target operating system bearing in mind the intended upgrades was carried out.

Taking into consideration the failings of MS-DOS as far as the system requirements are concerned, an investigation into available real time executives for conducted and a decision based on the requirements was made. Embedded GNU/Linux was chosen as the target software platform.

The software design of the application shows all the necessary design issues considered. The implementation phase of the thesis describes all the tools necessary to implement the embedded Linux system and all the components necessary to meet the needs of the Geosonde system. The network and serial interfaces were tested and shown to be fully functional. The XML based control in particular offers a more flexible and more platform independent solution than the serial interface.

Back to list of Group's MSc Theses


Nyareli T N

Development of a Cable Odometer with a Network Interface


An Odometer determines the position, speed and direction of the radar antennas as they survey the subsurface of interest. This Odometer is controlled on a web page via an ethernet connection.

The dissertation involves the design of a Cable Odometer that determines the position, direction and speed of a Radar as it surveys the subsurface. The Radar moves horizontally across the surface or up and down a borehole.

The distance moved by the Radar as it surveys the subsurface is determined from the rotations of a wheel, over which a cable passes. The Radar is attached to this cable. Information on the distance moved is collected by Odometer and used for further analysis on the Radar data.

The user requirement states that in some cases data collected by Odometer is used when triggering Radar directly to make surveys at fixed interval. In other cases the Radar operates autonomously. For the latter case the data collected by both Radar and dometer is related by a time-stamp.

The Odometer is controlled on a web page. Depending on the mode of operation chosen the user can transfer the time-stamped data to remote data storage via a network or store it on board (i.e. in Dataflash) for later downloading.

Back to list of Group's MSc Theses


Tanser D J

Simulation of a Slope Stability Radar for Opencast Mining


The suitability of a radar as a slope stability monitor for an opencast mine is investigated. The radar is required to detect the millimetric pre-cursory movements of a wall face which signal instability. An application-specific simulation was written in Matlab in order to develop a differential interferometric algorithm to detect any movement.

This algorithm was applied to real data and performed adequately. Temporal decorrelation and atmospheric variations were identified as likely error sources, and were investigated in turn using the simulation. Based on the results of the simulation, a scanning procedure is proposed to minimise these potential error sources.

The radar is assessed as a very suitable technique for monitoring slope stability. It is very accurate as an indicator of zero movement, and performs within the specified millimetric precision for small movements (less than 2 mm). For larger movements, the radar indicates that a movement has occurred but the accuracy is reduced. These larger movements are unlikely to occur with the proposed scanning procedure.

Back to list of Group's MSc Theses



Return to RRSG's Homepage

This page was last updated in January 2007 (RL)