Browsing by Author "Inggs, Michael"

Now showing 1 - 20 of 86
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    A 500kHz-5MHz CW stepped frequency borehole tomographic imaging system
    (2001) Isaacson, Adam Rhett; Inggs, Michael
    This dissertation involves a study of Cross-Borehole Tomography. The mathematical physical models of the Radon Transform are reviewed. The entire Cross-Borehole Tomographic process is simulated, based on these physical models of the Radon Transform. The system specifications for the final design are based on the results from the simulation. Finally, the final design is built, and tested. The phase yields a better quality of image reconstruction when compared to amplitude, and hence a coherent system is a good choice. The system is frequency to frequency coherent for the entire transmit frequency range, which satisfies the main aim of this dissertation.
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    Accelerating Gauss-Newton filters on FPGA's
    (2010) Da Conceicao, Jean-Paul Costa; Inggs, Michael
    Radar tracking filters are generally computationally expensive, involving the manipulation of large matrices and deeply nested loops. In addition, they must generally work in real-time to be of any use. The now-common Kalman Filter was developed in the 1960's specifically for the purposes of lowering its computational burden, so that it could be implemented using the limited computational resources of the time. However, with the exponential increases in computing power since then, it is now possible to reconsider more heavy-weight, robust algorithms such as the original nonrecursive Gauss-Newton filter on which the Kalman filter is based. This dissertation investigates the acceleration of such a filter using FPGA technology, making use of custom, reduced-precision number formats.
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    Accelerating software radio astronomy FX correlation with GPU and FPGA co-processors
    (2010) Woods, Andrew; Inggs, Michael
    This thesis attempts to accelerate compute intensive sections of a frequency domain radio astronomy correlator using dedicated co-processors. Two co-processor implementations were made independently with one using reconfigurable hardware (Xilinx Virtex 4LXlOO) and the other uses a graphics processor (Nvidia 9800GT). The objective of a radio astronomy correlator is to compute the complex valued correlation products for each baseline which can be used to reconstruct the sky's radio brightness distribution. Radio astronomy correlators have huge computation demands and this dissertation focuses on the computational aspects of correlation, concentrating on the X-engine stage of the correlator.
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    Acceleration of parasitic multistatic radar system using GPGPU
    (2011) John, Mathew; Inggs, Michael
    This dissertation details the implementation of PMR [Parasitic Multistatic Radar] signal processing chain in the GPGPU [General Purpose Graphic Processing Units] platform. The primary objective of the project is to accelerate the signal processing chain without compromising the algorithm efficiency and to prove that GPGPUs are a promising platform for parasitic radar signal processing.
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    Adventures in radio astronomy instrumentation and signal processing
    (2008) McMahon, Peter Leonard; Inggs, Michael
    This thesis describes the design and implementation of several instruments for digitizing and processing analogue astronomical signals collected using radio telescopes. Modern radio telescopes have significant digital signal processing demands that are typically best met using custom processing engines implemented in Field Programmable Gate Arrays. These demands essentially stem from the ever-larger analogue bandwidths that astronomers wish to observe, resulting in large data volumes that need to be processed in real time. We focused on the development of spectrometers for enabling improved pulsar² science on the Allen Telescope Array, the Hartebeesthoek Radio Observatory telescope, the Nançay Radio Telescope, and the Parkes Radio Telescope. We also present work that we conducted on the development of real-time pulsar timing instrumentation.
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    An airborne X-band synthetic aperture radar receiver design and implementation
    (2004) Mohungoo, Ajmal Ismail; Inggs, Michael
    This dissertation focuses on the design and implementation of an X-band receiver for use in the South African Synthetic Aperture Radar (SASAR II) project. The SAR will be used to demonstrate the capability of building a high resolution X-hand imaging radar in South Africa. The design starts by investigating the maximum power return from different targets over a swath width with changing incidence angles. A receiver-power-level table and diagram were constructed, with the power return from at trihedral corner reflector as maximum input power and thermal noise as the minimum input power to the receiver. The output of the receiver, which has to be fed to the input of an analogue-to-digital converter (ADC), is limited by the ADC's maximum operating input power. Amplifiers, attenuators and mixers were chosen to implement a dual-stage downconversion from a radio frequency (RF) of 9300 MHZ to a 2nd IF of 1300 MHZ and then to a 1st IF of 158 MHz. A sensitivity time control (STC) is implemented in the receiver to cater for the limited dynamic range of the ADC. The power return varies with range and hence, time. Thus, an STC will correct for low return power, at far range, by boosting the received signal and attenuating large return power, at close range, ideally providing a fairly constant power return at the receiver output. A manual gain control (MGC) is also needed in the receiver, such that none of the components are driven into saturation. The gain control is switched on when large targets are expected to fall in the swath width, otherwise it is switched to a minimum for targets with tow backscattered power. The tests that were carried out on the receiver components showed that all the components operated very close to their specifications. The cascaded filters work well in tailoring the front-end 3-dB bandwidth to close to the required 3-dB bandwidth. The receiver was designed to have enough gain to boost the maximum power received to within the operating range of the ADC, without saturating any components in the receiver. The noise figure test showed a noise figure of 4.20 dB. This is 1.73 dB higher than the calculated noise figure of 2.47 dB which is a result of an underestimation of the losses in the system.
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    Aspects of stepped-frequency processing for low-frequency SAR systems
    (2000) Lord, Richard Thomas; Inggs, Michael
    Ultra-wideband synthetic aperture radar (SAR) systems operating in the VHF/UHF region are becoming increasingly popular because of their growing number of applications in the areas of foliage penetration radar (FOPEN) and ground-penetrating radar (GPR). The objective of this thesis is to investigate the following two aspects of low-frequency (VHF/UHF-band) SAR processing: 1. The use of stepped-frequency waveforms to increase the total radar bandwidth, thereby increasing the range resolution, and 2. Radio frequency interference (RFI) suppression. A stepped-frequency system owes its wide bandwidth to the transmission of a group of narrow-bandwidth pulses, which are then combined using a signal processing technique to achieve the wide bandwidth. Apart from providing an economically viable path for the upgrading of an existing single frequency system, stepped-frequency waveforms also offer opportunities for RFI suppression. This thesis describes three methods to process stepped-frequency waveforms, namely an IFFT method, a time-domain method and a frequency-domain method. Both the IFFT method and the time-domain method have been found to be unsuitable for SAR processing applications. The IFFT method produces multiple "ghost targets" in the high resolution range profile due to the spill-over effect of energy into consecutive coarse range bins, and the time-domain technique is computationally inefficient on account of the upsampling requirement of the narrow-bandwidth pulses prior to the frequency shift. The frequency-domain technique, however, efficiently uses all the information in the narrowband pulses to obtain high-resolution range profiles which do not contain any "ghost targets", and is therefore well suited for SAR processing applications. This technique involves the reconstruction of a wider portion of the target's reflectivity spectrum by combining the individual spectra of the transmitted narrow-bandwidth pulses in the frequency domain. It is shown here how this method may be used to avoid spectral regions that are heavily contaminated with RFI, thereby alleviating the problem of receiver saturation due to RFI. Stepped-frequency waveforms also enable the A/D converter to sample the received narrow-bandwidth waveform with a larger number of bits, which increases the receiver dynamic range, thereby further alleviating the problem of receiver saturation during the presence of RFI. In addition to using stepped-frequency waveforms for RFI suppression, a number of other techniques have been investigated to suppress RFI. Of these, the notch filter and the LMS adaptive filter have been implemented and applied on real P-band data obtained from the E-SAR system of the German Aerospace Center (DLR), Oberpfaffenhofen, and on real VHF-band data obtained from the South African SAR (SASAR) system. Both methods significantly suppressed the RFI in the real images investigated. It was found that the number of range lines upon which the LMS adaptive filter could operate without adaptively changing the filter tap weights was often well above 100. This facilitated the re-writing of the LMS adaptive filter in terms of an equivalent transfer function, which was then integrated with the range-compression stage of the range-Doppler SAR processing algorithm. Since the range-compression and the interference suppression could then be performed simultaneously, large computational savings were achieved. A technique was derived for suppressing the sidelobes which arise as a result of the interference suppression of the LMS adaptive filter. This method was also integrated with the range-compression stage of the range-Doppler processor, leading to a very efficient implementation of the entire RFI suppression routine.
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    Calibration of a SuperDARN Radar Antenna by means of a Satellite Beacon
    (2012) Agaba, Doreen; Inggs, Michael; Cilliers, Pierre
    This dissertation reports on the investigation to determine which orbits, ionospheric conditions and seasons of the year that will facilitate the reception of the high frequency (HF) beacon signal from the 1 U CubeSat ZACUBE 1 by the SuperDARN HF radar in Antarctica, and by the HF direction-finding (DF) systems in both Pretoria and Hermanus. The primary objective of the HF beacon on ZACUBE 1 is to provide a continuous radio signal to calibrate and verify the elevation-resolving algorithm of the SuperDARN HF Radar antenna at SANAE IV in Antarctica. The signal will also be used to characterise the beam pattern of this and other HF radar antennas in the SuperDARN network, and to characterise the ionosphere over the Earth’s polar region. A secondary objective of the HF beacon on the satellite is to measure the ionospheric total electron content (TEC) by using either measurements of the carrier phase delays or of the Faraday rotation of the signal. An orbit analysis was done for the CubeSat using parameters for an orbit at an altitude of 600 km and inclination angles of 97.8° and 65°. To account for the propagation effects of the radio wave at 14.099 MHz, the IRI-2007 model and the Chapman layer model were used to define the ionosphere. A ray tracing algorithm written in MATLAB was used to simulate the ray paths. To evaluate the results, a documented ray tracing algorithm known as Haselgrove ray tracing was used. The results obtained show that for an orbit at an inclination above 70° and altitude of 600 km, a number of rays actually traverse the ionosphere and reach the receivers during most of the year for a sufficient period of time during every pass. The least refraction is experienced during winter, therefore it is the best time for the calibration of the radar antenna. The results indicate that the objectives of the CubeSat mission should be achieved.
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    Characterisation of a dual frequency conversion superheterodyne receiver
    (2008) Wu, Wai-Man Monica; Inggs, Michael
    This dissertation starts off with a brief introduction of the SKA project, and explain how it relates to the KAT project. Then certain receiver design techniques and parameters will be discussed together with receiver design trade-offs will be presented. This dissertation will then focus on the actual simulations of the 3x4 receiver module using the time-domain RF simulator, SystemView. An overview of the design for the 24-channel RF rack integrated locally by Tellumat (Pty) Ltd is presented and acceptance tests will be conducted and the test results will be presented.
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    Co-processor offloading applied to passive coherent location with Doppler and bearing data
    (2010) Milburn, Joe; Inggs, Michael
    This project dealt with the acceleration of an aircraft tracking algorithm using a ClearSpeed mathematical co-processor. The algorithm is based on non-linear differential correction (also known as the Gauss-Newton method) and uses Doppler and bearing data from a Passive Coherent Location (PCL) radar system. A PCL radar uses a network of receivers to track targets through their back-scatter from existing Continuous Wave (CW) transmissions, such as broadcast TV or radio. The lack of an active transmitter in a PCL system results in relatively low procurement, operation and maintenance costs. This is of particular advantage for airports in third world countries, many of which do not have radar assisted air traffic control.
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    Commissioning a 400 Hz rotary inverter
    (2009) Smith, Wayne Anthony; Inggs, Michael
    This dissertation covers the commissioning and testing of an aircraft's constant frequency alternator as the power supply for the Blue Parrot radar. The Blue Parrot is an X-band radar which forms part of the navigation and weapon-aiming system onboard the Buccaneer S-50 SAAF aircraft. The radar set uses a source of three-phase power at 400 Hz, which the constant frequency alternator can supply with the aid of certain auxiliary systems. The auxiliary systems include a prime mover, blower fan and a telemetering system. The prime mover has high starting currents which were reduced significantly by the use of a soft-starter. During testing, the constant frequency alternator started overheating and a blower fan was selected based on its thermal requirements. Significant cooling of the constant frequency alternator's case temperature was achieved by the use of a blower fan and shroud. The generator control unit monitors and regulates all parameters on the unit except for case temperature and blower fan pressure. A telemetering system was designed and built to monitor and display these parameters.
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    A comprehensive literature review of SAR polarimetric calibration for Waseda SAR Sensor
    (2015) Algafsh, Abdullah; Inggs, Michael
    This dissertation deals with a comprehensive literature review on SAR polarimetric calibration, as well as developing a polarimetric calibration procedure to be used for calibrating the sensor for the Waseda SAR project. The complete work is presented in six chapters. The dissertation starts by introducing Synthetic Aperture Radar Polarimetry (SAR polarimetry) by identifying the research objectives, and explains Waseda SAR project between King Abdulaziz City for Science and Technology and the University of Cape Town. A comprehensive literature review on SAR polarimetric calibration is introduced in the dissertation. The literature review explains the developments in calibration methods from the early 1960’s to recent years, including passive and active reflector advantages as well as the limitations for both reflectors. Also, displaying the received power as a function of polarization in a graphic way is presented in the dissertation known as the ‘polarization signature’. Two examples are used which are: the trihedral corner reflector and the dihedral corner reflector. The two examples are the theoretical reference for the calibration procedure for Waseda SAR sensor. The calibrated data set collected from NASA’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) over California is analyzed. The data is contaminated with an unrealistically high amount of coupling (-5 dB) to show the coupling effect on the data and then remove the amount of coupling to return the data to its original form. The dissertation concludes with a calibration procedure to be used for calibrating Waseda SAR sensor using the presented methods of SAR polarimetric calibration. The procedure involves using external devices such as: trihedral corner reflectors and dihedral corner reflectors as well as calculating the sizes of the reflectors and how the calibration flights are to be coordinated and instrumented with the reflectors.
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    The design and development of a pulsed radar block for the Rhino platform
    (2012) Raw, Bruce; Winberg, Simon; Inggs, Michael
    The Reconfigurable Hardware Interface for computiNg and radiO (Rhino) Platform is an FPGA based computing platform designed at the University of Cape Town to provide an FPGA resource that is both affordable and easy to learn and use in research and skills development in the areas of Software Designed Radio, Radio Astronomy and Cognitive Radio. A fremework comprising reusable radar processing modules (referred to in this text as "Radar Blocks") has been implemented on the Rhino and allows users to control simple pulse radar. The pulse radar application is implemented on the FPGA using the radar blocks framework which allows each block to be configured from the ARM processor to adapt settings during experiments. This project developed blocks for the communications bus, Gigabit Ethernet and simple pulse radar.
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    The design and implementation of a carrier card for the Karoo Array Telescope
    (2008) George, David; Inggs, Michael
    The Karoo Array Telescope [KAT] is a South African project that is attempting to build a worldclass radio telescope in the Northern Cape. The first prototype phase of the project was called the eXperimental Development Model or XDM. This MSc project involves the development of a carrier card that was planned to be used for XDM. The card, called the XDM Carrier Card, or XCC, was designed to be used as part of a modular Digital Signal Processing [DSP] architecture.
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    Design and implementation of a digital real-time secondary surveillance radar/identification friend or foe target emulator
    (2010) Neemat, Sharef; Inggs, Michael
    A real live test involving such a large number of targets would be extremely expensive, and difficult to repeat. There is thus a need for specialized target emulators to be developed and used as laboratory test equipment. This thesis describes the design and implementation of a transistor-transistorlogic (TTL) real-time SSRlIFF target emulator.
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    Design and implementation of a low-cost FMCW imaging radar
    (2016) Tchekashkin, Ivan; Inggs, Michael
    Imaging radar systems have been predominantly developed using a coherent pulse radar approach, which is typically associated with expensive and complex hardware that usually requires a large amount of space. Hence, the use of such sensors is reserved to large organizations that can afford to purchase or develop them. This is unfortunate as there are numerous uses for imaging radar sensors in both military and civilian sectors. One of such uses lies in the agricultural sector and entails using imaging radar data to monitor crop development. As a result, a project was initiated at the University of Cape Town (UCT), in collaboration with droneSAR company, which aimed to develop a low-cost, compact, imaging radar that could be mounted on a small Unmanned Aerial Vehicle (UAV). The purpose of this research project is aimed at developing the first system prototype. The RadioCamera-S is the S-band FMCW radar, that was developed to test the architecture that could be utilised to enable the filtering of the feed-through and nadir components, which are typically the strongest returns in the spectrum. The prototype has two modes of operation that are aimed at shifting the unwanted signals outside of the pass band of the receiver. This is achieved by generating two identical L-FMCW waveforms that are offset by a chosen time period. This enables a shift of the spectrum by the frequency, which corresponds to the time offset. The capabilities of the proposed hardware were examined and the specifications for the ground based version were developed. The parameters that influence the wave-form design were discussed and the optimal values were chosen for the ground based radar system. Verification of the transmitter and receiver operation was carried out, which was followed by system tests that demonstrated that the feed-through signal could be attenuated by employing the first proposed mode of operation. RTI plots were generated and showed that the radar was capable of detecting the movement of a reflector in the observable scene.
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    Design and implementation of a parallel registration algorithm for SAR images
    (2001) Fadiran, Oladipo O; Inggs, Michael; Wilkinson, Andrew John
    Registration of two or more images of the same scene is an important step in image processing that seeks to extract information not obtainable from one of the images in question. This process is required in many Engineering, Scientific and Medical applications. The accuracy of this step is crucial to the reliability of subsequent image processing and or decisions made on its basis. The huge size of the date to be processed, the speed at which the processing is required and the accuracy requirements necessitates a quick, efficient, robust and in some respects automatic program which efficiently harnesses available computing resources. This is the object of this project - the design of an image registration algorithm with a bias for SAR/InSAR applications but also applicable for other registration purposes, implemented on a parallel cluster of computing nodes.
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    The design and implementation of a radar simulator
    (1998) Lengenfelder, Rolf; Inggs, Michael
    This dissertation describes the design and implementation of a radar simulator called Sarsim2. The radar simulator was originally developed to produce synthetic range profiles (SRPs) of complex aircraft models. It was then expanded and upgraded to generate simulated synthetic aperture radar (SAR) data. Over the last few years a substantial amount of work has been carried out by the Radar Remote Sensing Group (RRSG) at the University of Cape Town (UCT) to produce SRPs of aircraft targets using an 1-Band search radar of Reutech Systems. The high range resolution that can be obtained from SRP processing makes it feasible to extract characteristic features from a profile obtained from an aircraft. The ultimate aim of producing SRPs is to use these extracted features for non-cooperative target recognition (NCTR) , i.e. to be able to identify an aircraft type from the echo signal received by the radar. The radar simulator was written to produce SRPs of aircraft models, which could then be used to investigate the feasibility of various aircraft-identification algorithms. The stepped-frequency processing required to obtain SRPs of aircraft targets has initiated further research in the RRSG into more efficient stepped-frequency processing techniques, and the radar simulator has been used extensively to generate simulated data . The RRSG group is also actively involved with SAR processing techniques, and the radar simulator has been invaluable in providing necessary simulation data to test various processing algorithms . One of the main objectives of this simulator was to have an easy-to-use graph ical interface, which can show results in real-time . This requirement makes it necessary to find some way of reducing the required computation. The solution implemented may be called VYSIWIC (what you see is what is calculated). This means that the data is only calculated to a resolution depending on the screen resolution. Only when the data is saved to disk will it be calculated and written with the required sampling rate.
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    Design and Implementation of a Secondary Surveillance Radar/Identification Friend or Foe Transceiver Card
    (2012) Alsaif, Saleh; Inggs, Michael
    The performance of SSR/IFF equipment, i.e. the transponder or the interrogator, can be tested by means of an SSR/IFF test set, which is usually extremely expensive, hard to transport and requires end-user certificates. This dissertation thus focuses on the design and implementation of a short-range real- time SSR/IFF Transceiver Card (ITRC), which can be used as an experimental platform for SSR/IFF test applications. User requirements are provided and analysed, resulting in a system breakdown structure, where for each subsystem a summary of related concepts is presented in order to produce the technical requirements for the system. The hardware was designed to be smaller, lighter, less expensive and easy to repair than conventional SSR/IFF test sets. When it has been integrated with an existing SSR/IFF reply emulator, it is capable of generating and analysing RF SSR/IFF signals for modes 1, 2, 3/A, C and secure mode 4 at a frequency of 1030 MHz and 1090 MHz in order to test the functionality of the interrogator and transponder. Verification for the design was accomplished by testing the transceiver hardware and then integrating the system with SSR/IFF transponder and interrogator. The results achieved were found to be compliant with the user requirements.
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    The design and implementation of a simulator for multistatic radar systems
    (2008) Brooker, Marc; Inggs, Michael
    This thesis presents the design and implementation of a signal level simulator supporting a wide variety of radar systems, and focusing on multistatic and netted radars. The simulator places few limits on the simulated system, and supports systems with arbitrary numbers of receivers, transmitters, and scatterers. Similarly, the simulator places no restrictions on the radar waveform to be simulated, and supports pulsed, continuous wave (CW) and carrier-free radar systems. A flexible model is used to describe the radar system to be simulated, with the parameters of the radar hardware, the properties of scatterers and the layout of objects in the simulated environment specified in XML format. The development of the simulation model focused on balancing the requirements of flexibility and usability, ensuring that the model can be efficiently used to represent any type of radar system. Oscillator phase noise is a limiting factor on the performance of some types of radar systems. The development of a model for the deterministic and static components of phase noise is presented. Based on this model, an algorithm for the efficient generation of synthetic phase noise sequences was developed, based on a multirate signal processing approach. This thesis presents this algorithm, and results of simulations of the effects of phase noise on synthetic aperture radar (SAR) and pulse-Doppler radar systems. The FERS simulator, an implementation of the simulation model presented in this thesis, was developed in the C++ and Python programming languages. This simulator is able to perform real-time simulation of some common radar configurations on commodity PC hardware, taking advantage of multicore and multiprocessor machines. FERS has been released as open source software under the GNU general public licence (GPL). Validation of the simulator output was performed by comparison of simulation results with both theory and measurements. The simulator output was found to be accurate for a wide variety of radar systems, including netted pulse-Doppler, moving target indication (MTI) and synthetic aperture (SAR) radar systems.