Browsing by Author "Langman, Alan"
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- ItemOpen AccessThe design and implementation of a distributed data capture and processing framework for ground penetrating radar(2001) Wallis, Allen Bruce; Langman, AlanThis dissertation describes the development of a distributed data-capture and data-processing framework for use with a network-aware ground penetrating radar. The software that was developed addresses weakness in existingg data processing software, with the main focus being on the distributed capabilities of the framework.
- ItemOpen AccessDesign of a low-cost high speed data capture card for the Hubble Sphere Hydrogen Survey(2008) Salkinder, Jason; Inggs, Michael; Langman, AlanThis thesis describes the design and implementation of a low-cost high speed data capture card for the Hubble Sphere Hydrogen Survey (HSHS). The Hubble Space Hydrogen Survey was initiated in an effort to build a low-cost cylindrical radio telescope for an all sky redshift survey with the observational goal to produce a 3-dimensional mapping of the bulk Hubble Sphere using Hydrogen 21cm emissions. This dissertation ï¬ rst investigates the system design to see how each of the user speciï¬ cations set by the planning team could be achieved in terms of design decisions, component selection and schematic capture. The final design. AstroGIG, satisï¬ es the user speciï¬ cations by capturing data up to a full power bandwidth of 1.7GHz with an instantaneous bandwidth of ≤ 250MHz white maximizing the dynamic range. AstroGIG buffers, processes, stores and ï¬ nally transmits the data through a 4-lane PCI-Express interface to a standard PC where the majority of the processing is performed. The system implementation is then described where issues relating to the process of transforming schematics into a physical PCB, and HSHS integration are discussed. The design is veriï¬ ed through Hyperlynx simulations to give a high degree of certainty that physical implementation and production would be successful. Results from tests on the actual hardware characterizing the overall system performance are presented. Conclusions are drawn based on these results and suggestions for future work and design improvements are recommended.
- ItemOpen AccessThe design of hardware and signal processing for a stepped frequency continuous wave ground penetrating radar(2002) Langman, Alan; Inggs, MichaelA Ground Penetrating Radar (GPR) sensor is required to provide information that will allow the user to detect, classify and identify the target. This is an extremely tough requirement, especially when one considers the limited amount of information provided by most GPRs to accomplish this task. One way of increasing this information is to capture the complete scattering matrix of the received radar waveform. The objective of this thesis is to develop a signal processing technique to extract polarimetric feature vectors from Stepped Frequency Continuous Wave (SFGWV) GPR data. This was achieved by first developing an algorithm to extract the parameters from single polarization SFCW GPR data and then extending this algorithm to extract target features from fully polarimetric data. A model is required to enable the extraction of target parameters from raw radar data. A single polarization SFCW GPR model is developed based on the radar geometry and linear approximations to the wavenumber in a lossy medium. Assuming high operating frequencies and/or low conductive losses, the model is shown to be equivalent to the exponential model found in signal processing theory. A number of algorithms exist to extract the required target parameters from the measured data in a least squared sense. In this thesis the Matrix Pencil-of-Function Method is used. Numerical simulations are presented to show the performance of this algorithm for increasing model error. Simulations are also provided to compare the standard Inverse Discrete Fourier Transform (IDFT) with the algorithm presented in this thesis. The processing is applied to two sets of measured radar data using the radar developed in the thesis. The technique was able to locate the position of the scatterers for both sets of data, thus demonstrating the success of the algorithm on practical measurements. The single polarization model is extended to a fully polarimetric SFCW GPR model. The model is shown to relate to the multi-dimensional exponential signal processing model, given certain assumptions about the target scattering damping factor. The multi-snapshot Matrix Pencil-of-Function Method is used to extract the scattering matrix parameters from the raw polarimetric stepped frequency data. Those Huynen target parameters that are independent of the properties of the medium, are extracted from the estimated scattering matrices. Simulations are performed to examine the performance of the algorithm for increasing conductive and dielectric losses. The algorithm is also applied to measured data for a number of targets buried a few centimeters below the ground surface, with promising results. Finally, the thesis describes the design and development of a low cost, compact and low power SFCW GPR system. It addresses both the philosophy as well as the technology that was used to develop a 200 - 1600 MHz and a 1 - 2 GHz system. The system is built around a dual synthesizer heterodyne architecture with a single intermediate frequency stage and a novel coherent demodulator system - with a single reference source. Comparison of the radar system with a commercial impulse system, shows that the results are of a similar quality. Further measurements demonstrate the radar performance for different field test cases, including the mapping of the bottom of an outdoor test site down to 1.6 m.
- ItemOpen AccessImplementing a ground penetrating radar user interface in system-on-chip technology(2005) Bauermeister, E F; Inggs, Michael; Langman, AlanGround penetrating radar technology is used to provide a fast and accurate method for target location compare to other geophysical sensing techniques. An existing ground penetrating radar system developed by Open Fuel (Pty) Ltd is used in the detection and avoidance of obstacles for a sub-surface horizontal directional drill mechanism. This ground penetrating radar system could be implemented as a portable surface-based version of the system for geophysical applications. A factor limiting its implementation is a personal or a laptop computer required to execute the human-machine interface software package for the radar system. Thus, there exists a need to produce a radar user interface to replace the computer required by the current ground penetrating radar system, while maintaining the original functionality of the radar system, while maintaining the original functionality of the radar system. The purpose of this design project was to develop a user interface for a ground penetrating radar system in hardware. The radar user interface had to allow for the autonomous operation of the ground penetrating radar system and the human-machine interface application software.
- ItemOpen AccessA reconfigurable accelerator card for high performance computing(2008) Aitken, Michael James; Inggs, Michael; Langman, AlanThis thesis describes the design, implementation, and testing of a reconfigurable accelerator card. The goal of the project was to provide a hardware platform for future students to carry out research into reconfigurable computing. Our accelerator design is an expansion card for a traditional Von Neumann host machine, and contains two field-programmable gate arrays. By inserting the card into a host machine, intrinsically parallel processing tasks can be exported to the FPGAs. This is similar to the way in which video game rendering tasks can be exported to the GFC on a graphics accelerator. We show how an FPGA is a suitable processing element, in terms of performance per watt, for many computing tasks. We set out to design and build a reconfigurable card that harnessed the latest FPGAs and fastest available I/O interfaces. The resultant design is one which can run within a host machine, in an array of host machines, or as a stand-alone processing node.
- ItemOpen AccessRHINO: reconfigurable hardware interface for computation and radio(2011) Scott, Simon; Langman, Alan; Inggs, MichaelField-programmable gate arrays, or FPGAs, provide an attractive computing platform for software-defined radio applications. Their reconfigurable nature allows many digital signal processing (DSP) algorithms to be highly parallelised within the FPGA fabric, while their customisable I/O interfaces allow simple interfacing to analogue-to-digital converters (ADCs) and digital-to-analogue converters (DACs). However, FPGA boards that deliver sufficient performance to be useful in real-world applications are generally expensive. Rhino is an FPGA-based hardware processing platform that primarily supports software-defined radio applications. The final cost estimate for a complete Rhino system is under $1700, cheaper than similar FPGA boards that deliver much lower performance.