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Abstract:
This project concerns the design and implementation of an elevation over azimuth position controller for a Navy Jammer pedestal. The position controller system is implemented on a Cogent CSB337 Single Board Computer using position resolvers to provide position information. The position controller accepts digital position commands moves the pedestal to the appropriate position.
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Abstract:
The oscilloscope is the most versatile electronic instrument one can have on ones work table today. It is a very expensive instrument however. I propose a new kind of an oscilloscope. A box of electronics, with a CPLD at its heart and VGA monitor as its visual output, that provides the functionality of an oscilloscope. This instrument should also be a fraction of the cost of conventional oscilloscopes. This thesis produces an instrument that fulfils this objective: A cheap oscilloscope that uses a VGA monitor as its output. It does not have the complete functionality of conventional scopes, but it can be significantly improved. It can be used in educational laboratories where financial resources do not permit the purchasing of the commercial oscilloscopes.
During the design process, literature was read of the various parts of the prototype system. The UP2 Development Board and QuartusII were the primary tools used in the design.
Experiments, Simulations and Research were the primary methods used to facilitate the design process.
The prototype design consisted of 3 main processes. These processes could however be broken down in many other process. This is an indication of the top-down design process followed.
The thesis was successful in that it produces a trace of the input signal on the VGA monitor. The input signal was a saw-tooth waveform.
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Abstract:
This project analyses an Ultra-wideband borehole radar system operating in a lossy, homogeneous medium. The medium is real and is characterised using mathematical formulae that model its dielectric characteristics. The Ultra- wideband borehole radar under analysis is the GeoMole Borehole Radar, de- signed to operate in mining environments and down to depths where surface penetrating radars are unable to remotely sense underground dielectric varia- tions.
The aim of the analysis is to extract the parameters of each component in the system, including the medium it is operating in, and model them in a scientific dynamic systems simulator package. The response of the simulated borehole radar system is to be recorded and the parameters extracted.
The validity of the extracted parameters is to be verified through comparison with the real GeoMole borehole radar and through analysis of its corresponding time and range profiles. The analysis of the GeoMole radar's performance concludes with a comparison between the simulated borehole radar's performance and that of a Stepped Frequency Ground Penetrating Radar. This comparison is made to verify which radar technology is a better performer in a ground penetrating application.
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Abstract:
Research into stepped frequency continuous wave ground penetrating radar (SFCW GPR) has been carried out since 1990 at UCT. However, this is the first thesis that discusses the simulation of SFCW GPR using SystemView. SystemView is a time domain system simulator environment for the design and analysis of engineering, mathematical and scientific systems. Frequency domain analysis of the signals in SystemView analysis window is also possible.
A SFCW GPR system was simulated in SystemView. Various transmitter configuration were discussed and the variable parameter configuration was found most suitable and therefore was used for the simulation. The variable parameter configuration was found most suitable because of its easily adaptable characteristics. When the variable parameter configuration was used, it was found that transmitter frequency can be made to cover any arbitrary frequency range, by a simple mouse click. Also the frequency stepsize and the number of frequency steps were automated when the increment value was changed, in this configuration. For the simulation, the transmitter covered the 1-100 MHz frequency band with the transmitter power of 10 mW.
The propagation medium, assumed soil with a constant relative permittivity, was simulated from a simple attenuator. For a constant relative permittivity, it was found that there is a linear relationship between the attenuation and frequency. Therefore, the real ground characteristics were simulated based on the attenuation versus frequency relationship. A heterodyne receiver architecture for the 1-100 MHz signal was simulated, to mix the signal to an IF of 1 MHz and demodulate the signal. Digitisation was performed by a 14 bit quantiser with a 2 V voltage span. The mean noise value was found important for signal averaging in post processing. Signal processing was not satisfactory, even though the performance was better than the Impulse GPR system. Zero-padding the range profile in signal processing improved the high range resolution profile. Stacking was found difficult in SystemView for the SFCW GPR, the machine ran out of memory when stacking was attempted. Therefore the alternative was found to be Matlab. This was left out for future work.
The system performance was tested by comparing the SFCW GPR to the Impulse GPR. In terms of the dynamic range, SNR, and transmit power, the SFCW performance was found better. Advanced signal processing methods were recommended for the SFCWto further shows its capabilities over the Impulse GPR. Other recommendations include medium and antenna future work.
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Abstract:
Synthetic Aperture radar uses long range propagation characteristics of radar signals and the complex information processing capabillity of modern digital electronics to provide high resolution imaging. It can provide high-resolution images from platform operating at long ranges, despite severe weather conditions. The University of Cape Town (RRSG) group are currently building a SASARll radar. This report is based on the simulation of the SASARll X-Band Imaging radar. The simulation uses chirp pulse as base-band signal. The report describes all the signal procesing techniques of the SASARll X- Band Imaging radar, component limitations on the system resolution in particular the noise and non-linearities they generate. ADC limitaions on the system resolutions are also adressed.
In this project the signal had to be processed, integrated i.e. adding many pulses like a real radar and demodulated down to baseband using digital demodulation technique because modern radar demodulation techniques employ this method, however time constraints could not permit neither pulse integration nor digital demodulation of the signal down to baseband to take place. The investigations that were to be carried out on the simualtion of the SASARll X-Band Imaging radar were based on the work that has already beeen established by Masters students.
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Abstract:
An existing 400Hz generator set which is mechanically linked to a 15 kW induction motor needed to be tested so that it could be used to generate 400Hz power for various radar systems in the department. The 400Hz generator used was obtained from an Mirage F1 and coupled with the induction machine through a special coupling unit built under contract outside UCT.
The 400Hz power supply was set up in the machines where several tests were carried out to determine the performance characteristics of the system. Since this particular design had not been tested before, a large part of this thesis involved identifying and sorting out operational problems with the 400Hz supply. After the 400Hz power supply system had reached a point where it was working efficiently, implementation designs such as the cooling mechanism and the platform design where done.
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