<p>A typical instrumentation problem is the detection of a differential signal in the presence of a common-mode signal. In the case of measuring myo-electric signals, the common-mode signals present can be 10²-10⁴ larger than the differential signal. In such instances, the attenuation of these unwanted common-mode signals require complex circuit designs.</p> <p>In this work an investigation of the common-mode signal path led to the development of a general approach to the problem of unwanted signals arising from common-mode signal sources. It was found possible to write the overall common-mode gain as a product of the differential amplifier common-mode response and the isolation gain. The isolation gain depends on the ratio of the impedance of the common-mode signal path to the differential amplifier input impedance. The impedance of the common-mode signal path may be increased by employing in the amplifier system a self-contained power supply and an output coupler device such as a transformer.</p> <p>The general approach was used to design an amplifier system to measure myo-electric signals. This amplifier system gave a much improved common-mode signal rejection over currently used systems which typically have 40 db of differential gain but only -30 db of common-mode gain at 60 Hz. The improvement in common-mode signal rejection was 25 db.</p> / Master of Engineering (ME)

<p>The main objective of this thesis is to investigate the spectral properties of Multi-h phase coding and to consider the trade-offs between error performance and bandwidth occupancy for this modulation method.</p> <p>There are multi-h phase codes which allow for a wide range of trade-offs. For example, there is a bandwidth efficient code which occupies 23% less bandwidth than Fast Frequency Shift Keying (Fast FSK) but required 2.4 dB more power to give the same noise immunity. There is also a code that needs 40% more bandwidth than Fast FSK but yields the same transmission quality with a 3.7 dB savings is power.</p> <p>The power spectrum of a multi-h code is line-free and the tail of the spectrum rolls off as 1/f⁴ as in Fast FSK.</p> <p>Three different methods for spectral analysis are presented and compared. We have found that approaches based upon the Wiener-Khinchin Theorem are to be preferred.</p> <p>Pelchat's analysis of binary FSK with continuous phase is extended to the general multi-index case.</p> <p>A multi-h code can be modelled as Markov chain and the auto-correlation function can be calculated using the theory for such processes. We have devised a simple procedure for identifying the states of the Markov chain.</p> / Master of Engineering (ME)

<p>A microprocessor based moment analyzer for the measurement of the first four statistical moments of a random or periodic signal has been developed and implemented. The processing circuitry uses the current state-of-the-art semiconductor components to produce an instrument that is cheaper and more compact then all previous implementations. It also provides more flexibility and demonstrates the current design philosophy of employing programmable LSIs as major building blocks. The instrument consists of two custom designed boards and utilizes the microprocessor as well as other facilities in an existing INTEL Prompt 80 microcomputer development system.</p> / Master of Engineering (ME)

<p>Dynamic stability of multimachine and single machine-infinite bus systems is considered. System models are described, which include detailed generator, turbine, governor and exciter components, in addition to dynamic representation of mechanical loads and electrical networks. The overall modeling concepts are applied to a number of practical applications to demonstrate their behavior in power systems dynamic studies.</p> <p>A variety of linear dynamic equivalents are employed to reduce the complexity of stability studies for multi machine power systems. Undrill's technique for constructing linear dynamic equivalents is extended and improved in this thesis.</p> <p>Various reduction techniques are applied to reduce the order of the system. Mainly they are aggregation and singular perturbations techniques. The interactions between the reduction techniques and dynamic stability are explained.</p> <p>Insights are presented into the interpretation of eigenvalues and eigenvalue sensitivities as they reflect the various aspects of power system stability predictions in high order models, they are extended to be applied in reduced order models.</p> <p>The concepts considered are employed in the analysis of several examples utilizing actual power system data.</p> / Master of Engineering (ME)

<p>Recent advances in the area of communications has inspired the concept of ubiquitous coverage onto the market place. A pocket-size mobile unit will be able to provide two-way messaging on a global perspective. In order to realize this "radio on a chip" philosophy small, rugged, low power and inexpensive components must be designed. In this thesis, new circuits and devices that meet this communication challenge are examined. These involve the use of surface acoustic wave (SAW) components and devices.</p> <p>The coupling-of-modes theory is used to study the effects of injecting a very small stimulus signal into a SAW oscillator loop. This diminutive injected signal may force the loop, if the conditions prevail, to follow and track it. These injection-locked oscillators (ILOs) follow the theory of phase locked loops (PLLs) to provide circuits suitable for amplification and demodulation of digital modulation signals. The locking phase angle of an ILO follows a similar sigmoidal shape found in neurons. An equivalent SAW ILO neuron circuit is presented and further developed into a self organized neural network. The SAW-based ILOs are then modified by controlling the quality factor of the SAW feedback element to produce carrier recovery, analog to digital converters and data multiplexer circuits. A very non-linear, near-chaotic ILO is introduced and examined with the aid of the Duffing equation. The Duffing model accurately verifies a periodic pulse generator employing a driven unlocked SAW ILO.</p> <p>A crucial component in any communication receiver is a "front-end" filter that eliminates any interfering frequencies that are close-in to the receiver channel. A study of such a component reveals that a dual-mode leaky-SAW resonator filter is ideal for the task. Antenna theory is applied to model the radiation conductance of thick-film interdigital transducers (IDTs) in dual mode wideband leaky-SAW resonator-filters on 64° Y-X LiNbO₃ employing a three-IDT structure. As well, SAW coupling-of-modes reflection-grating equations and IDT S-parameters are modified to cater for increased leaky-SAW attenuation above the Bragg frequency. Theoretical frequency response computations are in excellent agreement with experimental results obtained for several low-loss 85-MHz structures fabricated with metallization film thickness ratios (h/λ) of up to 3%.</p> / Doctor of Philosophy (PhD)

<p>Radar clutter, the unwanted radar echoes, has a long history of being modeled a.s a stochastic process. The main reason for using this model is that radar clutter appears to be very random to our naked eyes. Due to this stochastic assumption, radar detection is based on statistical decision theory. More precisely, the probability distribution of noise or clutter is obtained to derive the likelihood function for making decision.</p> <p>In this thesis, we try to justify the stochastic assumption of radar clutter, in particular, sea clutter. We find that assuming sea clutter as a random process uses unnecessarily high degrees of freedom. In other words, sea clutter does not have to be modeled by a random process to handle its random behavior. Using different real-life sea clutter data, we show that the random nature of sea clutter is possibly a result of the chaotic phenomenon.</p> <p>After showing that sea clutter is not truely random, we then try to model sea clutter data by a deterministic dynamical system. To construct a useful model for sea clutter, we need to reconstruct the dynamics of sea clutter, and neural network is used here as a tool to achieve this purpose. Two novel neural networks are developed to reconstruct the clutter dynamics. The first one is called rational function neural network which has an unique local minimum and a rapid learning phase. The second network, which uses the idea that sea clutter can be embedded as a manifold, does not require any learning, and is very robust and accurate. Both networks have excellent performances in reconstructing the dynamics of the real-life sea clutter data.</p> <p>The model for sea clutter is then used for detection of small targets in ocean environment. Now detection is no longer a statistic decision problem, but rather a process of distinguishing two different dynamical systems. One dynamical system contains trajectories for sea clutter and targets, and the other describes the motion of sea clutter only. We use the trajectory matching idea to classify different dynamical systems, and the result of detecting real-life small targets such as a waverider is very exciting.</p> / Doctor of Philosophy (PhD)

<p>This thesis summarizes the results of an experimental investigation into the advantages of receiver relative phase measurement, and transmitter polarization switching for the detection of co-operative polarimetric targets in ground clutter. In addition to assessing the impacts of these hardware enhancements, the investigation quantifies relative merits of linear and circular polarizations for this application. The final goal of this research is to quantify the detection performance improvements possible through both the hardware and processing enhancements described. These results will then be used to define the architecture of the next generation of polarimetric radar navigation systems. The investigation begins by reviewing the mathematical representation of polarized waves, and the ways that polarization has been exploited in past radar systems. Next, a mathematical reflectance model is developed for the proprietary trihedral twist grid reflector, and applied to predict anechoic chamber measured responses. An experimental field trip was conducted to measure this reflector and ground clutter using the National Research Council polarimetric precipitation measurement radar. The seven-dimensional radar echo measurements were described using multiple scatter plots and analyzed using the K-nearest neighbour rule pattern classification technique. The results of this analysis revealed that both transmitter polarization switching and receiver relative phase measurement should be used together, and that these two features can reduce the probability of false alarm by up to an order of magnitude without affecting probability of detection. Lastly, linear polarization was demonstrated as providing higher performance than circular polarization for the detection of tile co-operative targets in ground clutter, both using conventional amplitude detection, and also for the amplitude-correlation channel detection.</p> / Doctor of Philosophy (PhD)

<p>The subject presented in this thesis concerns the design and fabrication of microwave printed circuit log - periodic antennas meant for operation at frequencies above 1.0 GHz. The designs has its basis in the work which was presented by Robert L. Carrel as a Ph. D thesis in 1961 and is one of the classic papers in the design of log - periodic dipole arrays.</p> <p>The method is modified to some extent firstly to compensate for planar, instead of cylindrical dipole and the effect of the dielectric loading which the supporting substrate provides.</p> <p>Methods which allow feeding the array from the opposite direction in which the main lobe extends are also discussed, one of which, the mode converter, is found to be immediately successful.</p> <p>A typical antenna is fabricated, its input impedance and radiation pattern measured and the results discussed with some comparison to Carrel's results.</p> / Master of Engineering (ME)

<p>The use of harmonic mode SAW filters allows the fabrication of UHF oscillators with standard lithographic techniques. However, such devices previously required external filtering to select the desired harmonic. This in turn requires relatively high O circuits with their associated alignment problems and phase sensitivity.</p> <p>This thesis discusses a technique which permits harmonic operation without the external circuitry. By utilizing the theory of the end-fire array antenna a stepped-delay line has been fabricated at frequencies greater than 400 MHz using the fifth harmonic (i.e. fundamental at 80 MHz). The result is a packaged SAW oscillator which exhibited an output power of -15 dBm into a 50 Ω termination at a harmonic frequency of 404.3 MHz. Short term stability measurements made yield a short term stability of better than 1 part in 10⁹ over a period of 1 sec.</p> / Master of Engineering (ME)

<p>The electrical characteristics of a thin heavily doped layer in silicon were determined.</p> <p>A p⁺ 200 Ω/ m junction depth boron diffusion in a 2 Ω cm n-type phosphorous doped substrate was considered a typical thin heavily doped layer. This layer is of considerable practical importance being a standard base and resistor diffusion in planar processing.</p> <p>To completely characterize the heavily doped layer, it was necessary to study the layers on either side; substrate and thermal oxide; and their interfaces with the heavily doped layer. The resultant structure was examined by means of MOS C-V, oxide leakage and breakdown, Hall effect, p-n junction characterization, and differential sheet resistivity using anodic sectioning and a four-point probe. These tests yielded the impurity profile, the transport and recombination properties of the substrate, the dielectric constant thickness, breakdown field and leakage current of the oxide and the properties of the substrate diffused layer interface. However, the properties of the heavily doped layer and its interface with the oxide were still unknown. To find them, an experimental procedure utilizing a new test structure was introduced.</p> <p>The test structure consisted of an MOS capacitor formed over a heavily doped layer. The layer in turn formed one side of a p-n junction diode. The resultant structure was an MOS capacitor-emitter transistor (MOSCET). In operation, the p-n junction was reverse biased and became a minority carrier collector, while the MOS capacitor was biased into inversion for a controlled length of tire during which minority carriers were generated and formed the inversion layer. A voltage pulse applied to the MOS capacitor caused it to release minority carriers from the inversion layer. The carriers were transported across the layer under the combined influence of diffusion, and internal fields to the p-n junction where the charge that had not recombined during transit was collected.</p> <p>The theoretical behaviour of the MOSCET was determined. First a MOS capacitance program was used to determfne the inversion charge as a function of the bias voltage. Then a model of the device was developed to explain the transient response when no inversion charge was present. A finite difference formulation was used to account for the minority carrier transport across, and recombination in, the diffused layer. A time dependent release mechanism was introduced as a boundary condition which included values calculated in the non-inversion response. The result was a self consistent model of the MOSCET which also agreed with the other experimental data available.</p> <p>The MOSCET can be used to study two other phenomena as well as the characterization of thin heavily doped layers. This structure supplies the only direct confirmation of the relationship between inversion charge and bias voltage on the MOS capacitor. A study of the avalanche properties p-n junctions can be made, at very low multiplication values, with the MOSCET since the number of injected carries is so well known.</p> <p>Measurements on the MOSCET yield the following properties of thin heavily doped layers.</p> <p>(1) The minority carrier generation lifetime near the interface.</p> <p>(2) The generation centre energy level.</p> <p>(3) The average minority carrier recombination lifetime in the layer.</p> <p>(4) The transport properties across the layer.</p> <p>(5) The inversion potential.</p> <p>(6) The fixed oxide charge density.</p> <p>(7) The insulator stability.</p> <p>These properties combined with those determined by the other techniques provide the most complete electrical characterization of the thin heavily doped layer to date.</p> / Doctor of Philosophy (PhD)