<p>This thesis evaluates a bandwidth efficient data transmitting system which is modelled as a PRS system. A maximum likelihood receiver implementing VA is assumed at the receiving end. An algorithm is developed to compute a fundamental performance parameter of the system, called the free distance. 99% energy bandwidth and intersymbol interference (lSI) degradation are used to measure the performance of the system. Nonlinear programming and minimax methods are applied to find the optimal channel codes under different criteria. Three different sets of optimal channel codes have been found; first, the worst-case channel codes in terms of lSI degradation, secondly, the minimum 99% energy bandwidth channel codes and finally the minimum 99% energy bandwidth channel with fixed lSI degradation constraint. Two PRS systems with different pulse shaping filter are considered. First, an ideal low pass filter with minimum Nyquist bandwidth is evaluated for channel lengths up to twelve. Then a spectral raised-cosine filter with roll-off factor equal to one is evaluated for channel lengths up to four. The two PRS systems show that a longer channel can have better performance in consideration of both bandwidth and lSI degradation. The raised cosine filter causes no performance penalty in narrow band channels.</p> / Master of Engineering (ME)

<p>Complex automation systems, such as industrial robots, require a computer-based control system for the effective utilization of the advanced technology.</p> <p>A state-of-the-art was studied and presented in this thesis.</p> <p>A distributed computer control system for a modified Unimate 2000 robot, is presented. The 16-bit Intel 8086 microprocessor was used as the master computer, and the 8-bit Intel 8748 microprocessor as the slave processor.</p> <p>The system is effective and the experimental results agree with the simulation.</p> / Master of Engineering (ME)

<p>The demand for significant improvements in navigation systems, which must include more accurate and reliable position location, has been continuously growing in the last decade and is expected to increase rapidly in the near future. The need for this advanced position location and navigation system extends, not only to the airspace, but also to the surface of the earth where ships, land vehicles and aircraft in distress exist. Investigations have shown that satellite-based systems offer a number of unique advantages which meet the required characteristics of the future position location and navigation system. Whether the satellite system is designed to serve the entire earth or a certain portion of the earth, it is required that one or more satellites be visible simultaneously to the user. This necessitates the use of a satellite constellation which provides a multi-fold continuous coverage pattern. In this thesis, a detailed study of coverage patterns and design of satellite constellations for position location and navigation is presented. The metod employed relies on mathematical modelling and computer search f or the configurations of the optimal constellations. The selected optimization criterion is based on minimizing the cost through the minimization of the total number of satellites and satellite altitude. Several new mathematical models have been developed which eliminate the need for computer modelling. Computer search has been conducted based on the different models to determine the optimal satellite constellation for multi-fold continuous coverage. Results are presented throughout the thesis. Specifically, the analysis has led to the development of the following: 1. A mathematical model for a constellation of satellites in an equatorial orbits. 2. Two different mathematical models for a constellation of satellites in a network of polar orbits. A major development is the concept of the interaction between orbits to maximize the coverage. 3. Two mathematical models for a satellite constellation in a hybrid network which combines a network of polar orbits with an equatorial orbit. This type of constellation has not received attention in the open literature to date. 4. A model for a satellite constellation in a network of inclined orbits providing single-fold continuous coverage. 5. Five different satellite constellations in synchronous orbits for three-fold continuous coverage of the Atlantic Ocean. Finally, conclusions and a number of recommendations for future research are provided.</p> / Doctor of Philosophy (PhD)

<p>Various tests had been conducted in order to examine the stationarity and the normality characteristics of electrical control signals of the digestive tract. They were done because the conventional frequency analysis, which is used extensively for the investigation of biological signals, usually assumes the signal to be stationary and normally distributed. The validity of this assumption should then be examined before any further analysis is applied. The tests are conducted by proposing a null hypothesis that the signal under investigation is stationary and normally distributed. It was found that the percentage of rejection of the hypothesis increases towards the colonic end of the tract.</p> <p>Since conventional power spectral analysis does not provide any phase information on non-stationary signal, the bispectral analysis, which is the Fourier transform of the third moment; was used in order to examine many of the still-unknown characteristics of the gastrointestinal signal. The analysis mainly searches for any phase-locking between frequency components and hence identifies the generators of the signal. Two seperate analyses had been done : one was for a single channel and the other was for a double channel of signals. It was found that the same group of generators for the electrical signals on the upper part of the tract is present most of the time. But short-lived and locally based oscillators dominate the functions in the colon. From the cross-bispectral analysis, it was found that the generators in the stomach and the duodenum usually exert driving force to the distal site but bidirectionally in the jejunum. In the colon, only independent frequency components were found to be phased-locked occasionally.</p> <p>In conclusion, the analyses carried out in this study provide some alternate means to investigate many of the still largely unknown signals.</p> / Master of Engineering (ME)

<p>The problem of estimating the power spectral density of Gastrointestinal (GI) signals is studied. Classical nonparametric methods based on the discrete Fourier Transform are presented along with modern parametric methods which are generally based on autoregressive- moving average (ARMA) time series models. Some algorithms of ARMA parameter estimation are presented under the classification of optimal and suboptimal methods. Two recently proposed ARMA methods are particularly considered and proven to be equivalent. Additive interference between autoregressive signals is shown to produce an ARMA process with equal orders of the MA and the AR parts. This has been made use of in modelling and spectral estimation of the Electrical Control Activity (ECA) in the small intestine.</p> <p>Four methods for spectral estimation of GI signals have been implemented in a general minicomputer based program.</p> <p>The performance of the different methods is demonstrated by examples taken from small intestinal ECA. The spatial distribution and the temporal variations have been investigated for the ECA spectra in the small intestine.</p> / Master of Engineering (ME)

<p>In order to improve the performance of differential encoding systems, the encoding and decoding models have to change according to the speech waveform. The speech signal can be treated as quasi-stationary processes, which over a short period of time can be modelled by a certain set of parameters. Adaptive algorithms should be viewed as means of adjusting the system parameters.</p> <p>In this thesis, a 2.048 sec. long sentence has been studied by the Box-Jenkins time series procedure to determine the order of the linear prediction model and to investigate the need for adding moving-average terms. The algorithm suggested by Box-Jenkins for parameter estimation has been employed to update the parameters of the predictor of a prediction error coder each specific period of time.</p> <p>Since it is difficult to implement this algorithm on-line an alternative scheme has been studied. It is based on using the Box-Jenkins procedure to determine a suitable ARMA model and then updating the parameters of this model using a good on-line estimation algorithm. The applicability of the recursive least-squares and the stochastic approximation algorithms has been investigated. Stochastic approximation appears more promising as it takes less time for computation with an acceptable performance.</p> <p>As a result of this study, the addition of moving average terms to the predictor's model are shown to be necessary. But when Box-Jenkins' algorithm was tested with an ARMA model with adaptive and fixed initial parameters, it did not outperform the pure autoregressive model used with the same algorithm.</p> <p>The application or the three adaptive algorithms, the Box-Jenkins' approach, the recursive least-squares and the stochastic approximation, has been studied for the PEC configuration and the performance of the predictor was evaluated in each case. The results of this study indicate that combining stochastic approximation with the time series, and including an adaptive quantizer is applicable to differential encoder configurations, mainly the DPCM, with slight modificiations, and would yield better signal-to-noise ratio.</p> / Master of Engineering (ME)

<p>A system is designed for calculating on-line digital impedance of a transmission line using a Microprocessor (Intel 8085) and a Fast Multiplier (TRW TDC 1003J). The approach taken is to use a digital filter to extract the fundamental component of voltage V and current I, then the impedance is given by V/I. The filter is of the sliding or running spectral measurement type. The total time taken for impedance calculation is 1.033 msec for 16 samples in a cycle at the power line frequency of 60 Hz. The maximum absolute error is ±1.52% the largest possible impedance value.</p> / Master of Engineering (ME)

<p>This thesis addresses the problem of position control of an industrial robot. The robot used for this study is a modified UNIMATE-2000 with five degrees of freedom, which is dedicated to research in arc welding applications.</p> <p>The problem of position control of an industrial robot is first analysed. It is evident that due to several factors such as the elasticity of the arm, gravitational effects due to link orientation and load variations, a conventional fixed feedback controller is not adequate. It is therefore necessary to use an adaptive control scheme for position control.</p> <p>It is well known that the dynamics of a robot are non-linear and coupled, because of which it is not convenient to derive control laws which can be implemented in real time. Further, because the dynamics change as a function of link orientation and load variation, the model has to be evaluated on-line.</p> <p>In the past, robots were modelled from lays of classical mechanics. Although this scheme can result in accurate models, they are not suitable for adaptive control applications because of their complexity. In addition, this scheme of modeling requires a-priori knowledge of mass of links, specification of servo amplifiers and actuators. Often, to simplify models, dynamics of actuators and elasticity of links is neglected which results in unsatisfactory control.</p> <p>In this thesis we describe a new method for modeling the robot. The model is derived from experimental observations and does not require knowledge of the structure and internal subsystems of the robot. Further, it includes actuator dynamics and the elasticity of the arm. The method is demonstrated by modeling one axis of the UNIMATE-2000.</p> <p>Since the model is of non-minimum phase, the explicit pole-placement type of a self-tuning regulator was designed. Parameters of the model are updated at every sampling interval using a recursive Ieast squares estimator. Since, as mentioned before, dynamics of the robot change as a function of link orientation and Ioad variation, a 'weighting factor' is used for parameter estimation. Studies presented include the effect of truncation of controller parameters, adaptivity of the regulator to changes in system dynamics, and the effect of a variable weighting factor.</p> <p>Finally, several aspects of implementation of the self-tuning regulator, including selection of the controller structure, selection of the microprocessor, AID, D/A converter and programming language are discussed.</p> / Doctor of Philosophy (PhD)

<p>A polarimetric radar navigation (PRAN) system makes use of a specially modified marine radar and polarization rotating twist-grid retroreflectors in order to navigate a confined waterway, even in inclement weather or after dark. Despite the polarization diversity offered by such a radar target, depolarization allows significant cross-polar clutter to obscure the reflector return. The objective of the thesis is to successfully demonstrate the enhancement and detection of a cooperative cross-polar target.</p> <p>A field experiment is designed in Hamilton Bay, and 28 scans of real-time non-coherent HH-pol and HV-pol radar video recorded in a digital format from atop the Canadian Centre for Inland Waters, in Burlington, Ontario. The two reflectors are located at sites in the Dofasco area and the La Salle Park area. A conventional cell-averaging CFAR processor is initially used to give a benchmark against which to compare joint signal processing methods. A dimensionless normalized target-to-clutter ratio (NTCR) is introduced to quantify performance, along with standard sub-images to subjectively show the effect of the processing.</p> <p>An adaptive cross-polar interference canceller is designed which processes the dual-polarization channels jointly, reducing the nonstationary clutter variance and enhancing the target. An analog implementation of the processor was granted Canadian and U.S. patents.</p> <p>In another approach, mutual information based unsupervised learning of linear and nonlinear networks is investigated. The RBF network is shown to greatly enhance cross-polar reflector response in the non-Gaussian statistical environment.</p> <p>Next, a modular solution integrates all three methods to produce superior reflector enhancement in average and peak clutter.</p> <p>Finally, a novel post-detection processor is demonstrated that successfully uses a priori information about the reflector location along the water-land boundary of the waterway. A fuzzy processor combines primary detection information with the output from a vision-based edge detector to effectively remove false alarms.</p> / Doctor of Philosophy (PhD)

<p>A C-band four-element integrated receiver system for digital beamforming (DBF) has been designed and implemented. For an array with digital beam processing, as a means of achieving precise pattern control (low sidelobe, adaptive nulling and high resolution) over large bandwidth and large dynamic range, the use of self-calibration techniques and circuitry was studied and evaluated. A multilayer linear self-calibration loop was also suggested and developed. Furthermore, in this thesis, the use of active antennas and optically controlled microwave devices in DBF systems was investigated.</p> <p>Integrated antennas, as the first stage of the whole DBF system, are required for overcoming excessive power loss in large microstrip array antennas, for avoiding degraded array far-field pattern performance due to spurious radiation from microstrip feed networks and for larger effective isotropic radiated power (EIRP). The possibilities of using active antennas instead of conventional passive antennas are studied. Several new active antenna structures were proposed and implemented. Detailed design procedures and experimental results were given. Other applications for spatial power combiners and larger active antenna arrays were also addressed.</p> <p>The optical control of microwave devices and subsystems is a rapidly growing area of research. In this thesis, the possibilities of using optical control in DBF systems are discussed. This thesis also describes the first reported application of frequency-dependent finite-difference time-domain ((FD)²TD) method for modelling optoelectronic microwave semiconductor devices. The two major effects of a constantly illuminated semiconductor plasma which must be analyzed are: (i) the strong influence of carrier diffusion and recombination-generation processes on photoconductivity and (ii) the depth to which the plasma penetrates the device. Two examples of using modified (FD)²TD method to analyze a two-dimensional optically controlled dielectric resonators and three-dimensional optically controlled phase shifters/attenuators are presented. Finally the comparison between available experimental results and theoretical results are discussed.</p> / Doctor of Philosophy (PhD)