Department of Electrical and Electronic Engineering
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Electrical and Electronic Engineering is an exciting and dynamic field. Electrical engineers are responsible for the generation, transfer and conversion of electrical power, while electronic engineers are concerned with the transfer of information using radio waves, the design of electronic circuits, the design of computer systems and the development of control systems such as aircraft autopilots. These sought-after engineers can look forward to a rewarding and respected career.
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Browsing Department of Electrical and Electronic Engineering by browse.metadata.advisor "Bakkes, P. J."
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- ItemAspects affecting the design of a low earth orbit satellite on-board computer(Stellenbosch : Stellenbosch University, 2000-12) Grobler, H.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Satellites are not all made equal. The large number of possible orbits, desired functionality and budget constraints are but a few of the factors that influence the design of a satellite. Given a particular set of design requirements, a number of designs may meet these requirements. Each of these designs will typically entail a trade-off between a number of (conflicting) parameters, whilst still satisfying the system requirements. The On-Board Computer (OBC) of a satellite, the satellite subsystem primarily responsible for the operational control of a satellite, can consequently be designed in any of a number of different ways. As the factors that influence the flight performance of an OBC differs to those of a terrestrial computer, the OBC design will therefore be significantly different. A high-level overview of the factors that impact OBC design and operation is presented. Improvements to the existing designs are proposed. In conclusion, a number of guidelines for a future OBC design also are given.
- ItemThe design of a CMOS sensor camera system for a nanosatellite(Stellenbosch : University of Stellenbosch, 2006-12) Baker, Eric Albert; Bakkes, P. J.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.This thesis relates to the design of a camera system for a nanosatellite based on a CMOS image sensor. The design specifications and constraints are considered followed by the proposal of a versatile design with all the required functions imple- mented on a single FPGA. These functions include bad block management, data routing, an EDAC, a soft-core processor, glue logic to external devices, and com- munication busses. The Altera Nios II soft-core processor is implemented in this design, which en- ables simple changes to be made in software. A good mixture of intellectual prop- erty soft-cores, open-source cores, and user created logic are utilised in this broad base design, containing a combination of hardware, digital logic, and software. Low power and compact devices are selected for this design to minimize the power usage and the physical size of the camera system. The system's peak power consumption is 952mW which is below the required maximum consumption of 1W. This design's performance is therefore ideal for a subsystem onboard a nanosatel- lite.
- ItemDesign of a distributed satellite ground system(Stellenbosch : Stellenbosch University, 2001-12) Barry, Richard Malan; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: This thesis describes the development of a distributed ground support system to be used in the small satellite program at the University of Stellenbosch. A literature study was done to determine the current trends in ground support design. These trends are presented together with an analysis of the SUNSAT groundstation software. New technologies in the field of distributed systems are discussed and used in the design of a distributed ground support system. The design centres around a servicesbased architecture where services are distributed on the network. The design is evaluated according to attributes exhibited by effective distributed systems. Certain services were implemented to demonstrate the feasibility of the design. The implementations are discussed and suggestions are made for future improvements and fields of possible further study.
- ItemDesign of a reliable telecommand system for the Sunsat microsatellite(Stellenbosch : Stellenbosch University, 1994) Botha, Tielman F.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The aim of this thesis is the generation of a telecommand system for use on the Sunsat microsatellite. This includes the hardware module for integration in the satellite as well as ground station control software. The telecommand system is defined. Functional requirements are specified and used as basis for a conceptual design. In this conceptual design three different paths to the telecommand usisng three different architectures are implemented. Data sources used for control purposes are the two main on-board computers as well the ground station via four different modems.
- ItemThe design of CAN nodes for minimising cables on the SUNSAT's TCMD system(Stellenbosch : Stellenbosch University, 2003-12) Musetha, Rendani D.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The aim of this thesis is to investigate a design of a microcontroller based embedded system that will be used to minimise cable harness on the SUNSAT micro-satellite. The system is called CAN node. The CAN node(s) implements CAN (Controller Area Network) serial bus architecture protocol. The protocol is implemented on the two nodes to transport data from the TCMD tot he 0 ther trays 0 f SUNSAT. CAN node( s) design proj ect focuses on the TCMD tray, because it is the central point for data communication in SUNSAT and it acts as the eyes and hands of the satellite's operator. As a result most of the communication cables are located at this tray. The two nodes are called TX-node and RX-nodes. The TX-node is used to collect data from the TCMD tray and transmits them serially to RX-node. The RX-nodes receives the TCMD data from TX-node and transmits these data to their respective nodes. In application RX-nodes need to be ten, but only one is used for testing purpose. The design had its shortcomings, of which they are discussed in this thesis. The recommendations of an ideal system are also given to elaborate how the system should behave in the real situation. Despite its shortcomings, the CAN node(s) project has successfully proven that cable harness on the TCMD tray of SUNSAT can be minimised by using CAN technology.
- ItemDevelopment of a high speed PCI data capture card for the SUNSAT I ground station(Stellenbosch : Stellenbosch University, 2002-03) Van der Westhuizen, W. J. (Willem Joseas); Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The primary payload of the University of Stellenbosch's micro-satellite, SUNSAT I, was a high quality imager, capable of taking stereoscopic images of the surface of the earth. Although the orbit of SUNSAT I will have the satellite pass over the whole earth, contact via the SUNSAT I ground station at the University will only be made for 3% of each day. To be able to photograph any part of the earth onboard memory was provided on the satellite to store the image until it can be downloaded to the ground station. A high speed downlink was also added to the satellite to be able to download a complete image from the onboard memory in one pass and also to take realtime pictures as the satellite passes over the ground station. At that stage there was no way to capture the data at the ground station. A high speed digital data capture mechanism was needed. The thesis discusses the development of a high speed capture card. Due to the high speeds needed it provided an excellent opportunity to develop the card using the PCI bus, the first design to do so at the University, as an interface with a computer. A prototype card was developed first to do proof of concept. It is shown that the prototype card fulfilled the functional requirements and it was also used to capture the first image from the complete satellite during the final tests before launch. Finally a production card for use in the ground station was designed and assembled.
- ItemThe development of a mass memory unit for a micro-satellite using NAND flash memory(Stellenbosch : Stellenbosch University, 2005-04) Horsburgh, Ian J.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: This thesis investigates the possible use of NAND flash memory for a mass memory unit on a micro-satellite. The investigation begins with an analysis of NAND flash memory devices including the complexity of the internal circuitry and the occurrence of bad memory sections (bad blocks). Design specifications are produced and various design architectures are discussed and evaluated. Subsequently, a four bus serial access architecture using 16- bit NAND flash devices was chosen to be developed further. A VHDL design was created in order to realise the intended system functionality. The main functions of the design include a sustained write data rate of 24 MB/s, bad block management, multiple image storing, error checking and correction, defective device handling and reading while writing. The design was simulated extensively using NAND flash simulation models. Finally, a demonstration test board was designed and produced. This board includes an FPGA and an array of 16 8-bit NAND flash devices. The board was tested sucessfully and a write data rate of 12 MB/s was achieved along with all the other main functions.
- ItemThe development of an ARM-based OBC for a nanosatellite(Stellenbosch : University of Stellenbosch, 2007-12) Brand, Christiaan Johannes Petrus; Bakkes, P. J.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.Next-generation nanosatellites are becoming a very cost effective solution to gain access to space. Modern manufacturing technology together with low power low cost devices makes the development of nanosatellites, using standard industrial components, very attractive. A typical nanosatellite will have only one microprocessor, capable of performing all the computing tasks onboard the satellite - housekeeping, AODC (Attitude and Orbit Control) and instructing the different payloads aboard the satellite. One of the major requirements was to choose a processor from a dominant manufacturer in the market that will still be available for future satellite missions. Just as the 8051 dominated the 8-bit market, the ARM7 processor is fast becoming a market leader in the segment for 16-bit applications. ARM processors has also been used much in handheld devices in recent years - which emphasize the low power requirements and stability of these processors in embedded applications. This thesis investigates the different processors that are currently available. A complete system design is done, taking into account all the different modules needed onboard a very small Low Earth Orbit (LEO) satellite. Finally, some test results are given showing how this system can be reliably used onboard a nanosatellite in future.
- ItemDevelopment of an integrated fuel management system with the aid of CPLDs(Stellenbosch : Stellenbosch University, 2000-12) Swanepoel, S.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The need for a locally manufactured, cost-effective, fuel management system led to the design and development of a functional prototype. This thesis presents the design, development and full implementation of two functional prototypes. While field tests performed on the first prototype assisted in identifying necessary modifications, a need for greater complexity in support hardware was also identified. In order to comply with the cost-effective nature of the project, it was realized that this complexity could only be achieved via the implementation of a CPLD based system. Using Altera's Maxplus II design software, the CPLD code was synthesized according to the required specifications then simulated and analyzed On completion of the new CPLD based system, the second prototype, one of Altera's megacore functions is implemented and used as a substitute to an external hardware. All necessary modifications were successfully completed and the system was installed.
- ItemThe evaluation of an ARM-based on-board computer for a low earth orbit satellite(Stellenbosch : Stellenbosch University, 2002-12) Dreijer, Gregor (Gregor Steve); Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The use of commercial-off-the-shelf (COTS) components and emerging technologies in satellite systems has become increasingly popular over the past few years. This is mainly due to advances in radiation shielding and system-level reliability improving techniques. The use of a new generation commercial processor in the design of a satellite's on-board computer (OBC) is now considered a feasible option. The aim of this thesis was to evaluate the use of a commercial grade ARM processor in a low earth orbit (LEO) microsatellite on-board computer. The process began with the selection of the most suitable ARM processor for an aBC design. A typical aBC system was developed for the chosen processor, in order to test its functionality and performance in anOBC design.
- ItemFeasibility of the PowerPc 603ETM for a LEO satellite on-board computer(Stellenbosch : Stellenbosch University, 2002-12) Vos, Jacu; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: For space designs, just as for terrestrial applications, the appetite for more computing power is virtually insatiable. Further, like portable applications, space use implies severe power constraints. Among currently available commercial processors, the PowerPC family ranks high in Million Instructions Per Second (MIPS) per watt, but its suitability for space applications outside low-earth orbits (LEOs) may be limited by the radiation environment, particularly single ev nt effects (SEE). This thesis covers the feasibility of using the PowerPC 603e™ processor for LEO satellite applications. The PowerPC architecture is well established with an excellent roadmap, which makes for a baseline microprocessor with long-term availability and excellent software support. The evaluation board design leverages Commercial Off-The-Shelf (COTS) technologies, allowing early integration and test. It provides a clear path to upgrades and provides a high performance platform to suit multiple missions.
- ItemFeasibility of using an ARM processor in a micro satellite on-board computer(Stellenbosch : Stellenbosch University, 2001-12) Barnard, Arno; Bakkes, P. J.; Stellenbosch University. Faculty of Faculty of Engineering . Dept. of Electrical and Electronic Engineering.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.
- ItemHoe spoed koppelvlak vir n nuwe generasie SUNSAT mikrosatelliet(Stellenbosch : Stellenbosch University, 1999-12) Strydom, H. L.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering.ENGLISH ABSTRACT: A micro-satellite is a complex system constructed of a number of subsystems. Communication interfaces must exist between these subsystems to exchange data, for example telemetric and telecommand. In order to receive all data, these interfaces must be efficient and reliable. Failure of an interface can result in an unuseable subsystem, which could affect the satellite. The aim of this thesis was to investigate alternative possibilities for the implementation of a high-speed interface between the main camera and mass-memory. On the first generation SUNSAT the interface was realised by sending the analog image-information of the different colours, parallel to the mass-memory, where information is converted to digital data and latched into the main memory. This leads to limitations of the interface, and the disadvantages will be discussed. Various parallel and serial technologies are investigated and discussed. LVDS was chosen as the most suitable technology and was used to design the interface. This technology has the advantage of implementing a serial bus, using low differential voltages for the transmission of data. This minimises the use of power and noise. The high bandwidth of LVDS also allows an errorprotocol to be implemented. As part of the errorprotocol, an EDAC is implemented to correct single biterrors, but it needs a higher bandwidth, which is a disadvantage. A limited-queue can be used to resend data for any other errors, but it is impractical to implement a bigger memory on the sending side. The errorprotocol is implemented and simulated and is discussed in this thesis.
- ItemInvestigation of a command and data handling architecture for the SUNSAT-2 micro satellite(Stellenbosch : Stellenbosch University, 1999-12) Koekemoer, Jan-Albert; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering.ENGLISH SUMMARY: This thesis investigates the design of a Command and Data Handling (C&DH) system for possible use on future SUNSAT satellites. The investigation begins with a description of the underlying components of a general C&DH system, namely telemetry (TLM) and telecommand (TCMD). From the subsequent evaluation of these subsystems on SUNSAT-1, several recommendations to improve their functionality on the proposed C&DH design are made. Preliminary design specifications and requirements are then set up for the new design. The main requirements are flexibility and reliability. A logical improvement from the centralised TLM and TCMD designs used on SUNSAT-1, is identified, namely a bus architecture for the proposed C&DH system. Several bus technologies are subsequently evaluated and from this, Controller Area Network (CAN) technology is chosen as a suitable, relatively high speed serial bus. Several system architectures to implement CAN with on the C&DH system are then evaluated. The concept of CAN nodes within the C&DH system is explained, and from this, the detail of such a node is presented, designed, and implemented in the form of a prototype hardware system. The performance of the prototype is then evaluated against the set specifications and requirements. Other work related to the design of a C&DH system covered in this document, includes the evaluation of several international TLM and TCMD standards. From these, the recommendations ofthe Consultative Committee for Space Data Systems (CCSDS) are identified as a possible down- and uplink protocol on future satellites.
- ItemMobile radio data network for documentation display(Stellenbosch : Stellenbosch University, 2000-04) Du Toit, Rene; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: This product is designed as an educational tooL It was developed to make a classroom more organised. Better and easier communication between the teacher and the students can be established, as well as improved communication between different classrooms. The stand alone unit can be used anywhere because there is no wiring between this and the computer. It can be a big addition to the educational system, especially in places where books are not readily available for the students. The system consists of various components. These components are a computer, a stand alone unit and an interconnection for these two. The interconnection was incorporated with the use of radio links. At the computer side of the design, a windows interface was developed to enable the computer user to communicate with the stand alone unit user. The radio link was inserted to make the communication between the computer and the stand alone unit wireless. The stand alone unit consists of a keypad, liquid crystal display, serial port and a floppy drive. The serial port is used as connection between the stand alone unit and the radio links. It is possible to expand the system. The keypad can be replaced by a keyboard to enable the stand alone user to type and save data on the stand alone unit itself, and a hard drive might be added to increase the storage space. The inclusion of the floppy drive makes the system more compact and creates the possibility of transferring data by use of the floppy, which in tum does not limit a person to working only in one place.
- ItemA new approach to embedded computer benchmarking(Stellenbosch : Stellenbosch University, 2006-04) Smit, Willem A.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Years of experience gained in the field while designing and building new digital hardware for clients in both the private and public sectors have shown that choosing the correct processor for the job beforehand is difficult. The reason is the type of situation where the final speed of the application cannot be known before it is tested on the actual hardware, but that the hardware cannot be built before it is known which CPU will be fast enough to run the application. Designers have traditionally tried to reduce the risk by referring to various benchmark programs to compare processors with each other, and then by over designing. In this regard various attempts have been made to describe the performance of CPU's, but these are generally very application-specific and the accuracy depends on who is doing the measuring. Manufactures have been known to quote figures that will portray their hardware in the best possible light. The purpose of this thesis will be to develop a robust, simple and quick way to determine what performance a CPU will achieve in a given practical application. The theory will then be tested on several CPU platforms. The development of such a method has very practical application in the engineering industry, as the type and number of CPU's in a design have very real cost implications. The method will also have spin-offs in the System-On-a Chip (SOIC) and FPGA environment when the method is used to analyse the requirements of a given application. The results can then be used to influence the data flow paths and CPU architecture of such a design. The thesis first does a literature survey of current benchmarking methods. This will then be used to influence the postulation of a theory of how the problem of benchmarking should be tackled. The theory will then be tested on several platforms, as stated above.
- ItemOndersoek na die gebruik van CAN in 'n laespoed kommunikasie stelsel vir 'n volgende generasie SUNSAT mikro satelliet(Stellenbosch : Stellenbosch University, 1999-12) Steyn, C. H.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering.ENGLISH SUMMARY: The communication structure of the current SUNSAT 1 micro satellite employs a parallel architecture, which consists of a number of different unique interfaces. The current system however has some undesirable properties, some of which are the high processor load and the amount of different interfaces that exist. For a next generation SUNSAT micro satellite the need arose for a new communication structure, which replaces the parallel structure with a network system. In this thesis the CAN (Controller Area Network) protocol is evaluated for implementation in a possible next generation communication system. Different systems are evaluated and the properties of each system are discussed.
- Item'n Ondersoek na die geskiktheid van 'n datavloeiverwerker as 'n herstruktureerbare spesiale verwerker(Stellenbosch : Stellenbosch University, 1984-11) Loubser, Nicolas Johan; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering.AFRIKAANSE OPSOMMING: Hierdie tesis behels 'n ondersoek na die geskiktheid van 'n datavloei-verwerker om as 'n herstruktureerbare spesiale verwerker te dien. Die werking van 'n datavloei-verwerkermodel word aan die hand van datavloeikonsepte verduidelik. Die tekortkominge van die model, naamlik die gebrek aan datastruktuur-hanterings, toevoer/afvoer en hertoelatingsmeganismes wor-d uitgelig en moontlike oplos~ings word gege•• 'n Semodifiseerde datavloei-model, wat beide struktuurhantering en toevoer/afvoermeganismes insluit, word voorgestel. Hertoelating word met behulp van 'n datapakketbenamingsmetode bewerkstellig. Om die programmeerbaarheid en die herstruktureerbaarheid van die model te ondersoek, is besluit om 'n datavloei-verwerker te simuleer. Die model is met behulp van die hoevlaktaal PASCAL, en bedryfstelselroepe op die VAX 11/780 rekenaar gesimuleer. ParallelIe verwerkingskonsepte in beide programmatuur en argitektuur word gedemonstreer.
- ItemProtection unit for radiation induced errors in flash memory systems(Stellenbosch : Stellenbosch University, 2004-12) Bryer, Bevan; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Flash memory and the errors induced in it by radiation were studied. A test board was then designed and developed as well as a radiation test program. The system was irradiated. This gave successful results, which confirmed aspects of the study and gave valuable insight into flash memory behaviour. To date, the board is still being used to test various flash devices for radiation-harsh environments. A memory protection unit (MPU) was conceptually designed and developed to morntor flash devices, increasing their reliability in radiation-harsh environments. This unit was designed for intended use onboard a micro-satellite. The chosen flash device for this study was the K9F1208XOA model from SAMSUNG. The MPU was designed to detect, maintain, mitigate and report radiation induced errors in this flash device. Most of the design was implemented in field programmable gate arrays and was realised using VHDL. Simulations were performed to verify the functionality of the design subsystems. These simulations showed that the various emulated errors were handled successfully by the MPU. A modular design methodology was followed, therefore allowing the chosen flash device to be replaced with any flash device, following a small reconfiguration. This also allows parts of the system to be duplicated to protect more than one device.
- ItemA second generation SUNSAT RAMDISK(Stellenbosch : Stellenbosch University, 2000-12) Rust, A. N.; Bakkes, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The SUNSAT RAMDISK was studied, and tests performed to assess its flight readiness. Errors were detected, and modifications had to be made to ensure proper operation. SUNSAT was subsequently launched, and to date the RAMDISK is still functioning correctly. The flight readiness testing of the RAMDISK was considered a pre-study to designing a second generation RAMDISK. A conceptual mass memory storage device support structure was designed. This second generation RAMDISK, or memory drive is intended to be used on a second generation SUNSAT, or SUNSAT 2. The design is targeted for implementation in fields programmable gate arrays (FPGA's) and was realised using VHDL. This hardware description language is an accepted standard, and can be implemented in a number of different programmable logic devices; both SRAM and fuse-link based. Simulations were performed to verity the functionality of the design, and to determine whether the data transfer specifications could be met using programmable logic devices. A modular design methodology was followed. The memory drive was designed so that any type and amount of memory can be added to the drive without a major design change. The simulations indicated that a data capturing speed of 130 Mbits/s could be maintained.