This dissertation makes a study of frequency discriminators and their role in instantaneous frequency measuring (IFM) signal acquisition receivers. Frequency discriminators are the major building blocks of IFM. They are required to measure frequency accurately over very broad bandwidths and to have near unity probabilities of pulse intercept. The major difficulties of the most commonly reported version are identified as a lack of component symmetry and a need to cross over two transmission lines while maintaining isolation. The accuracy due to lack of symmetry shows up analytically. effect on TOUCHSTONE, a micro-computer analysis package, is demonstrated as an excellent analysis tool while alternatives are also suggested. Variations of the standard discriminator are discussed. These are intended to improve performance due to lack of symmetry. None completely solve the cross over problem. A new type of discriminator requiring fewer components is introduced. It requires no cross over and exhibits greater symmetry. Analysis indicates that it performs better than the standard version. Two prototypes show the methods to be reliable and confirm the promise of the new version.

Thesis (M.N.R.M.)--University of Manitoba, 2001. / Includes bibliographical references (leaves 119-138).

No description available.

No description available.

No description available.

No description available.

Using high-resolution topography, we link the stratigraphy of layered ice deposits at the north pole of Mars to astronomically driven climate variability. Observations of trough exposures within these deposits are used to construct virtual ice cores at 16 sites, to which we apply wavelet analysis to identify periodicities in layer properties. To confidently relate these periodicities to climatic forcing, we identify overlapping dominant stratigraphic wavelengths and compare their ratios to that of the two dominant modes of insolation variability. The average ratio of stratigraphic wavelengths in the profiles is 1.90.1, lower than the ratio of 2.3 between dominant insolation periodicities. A similar analysis of synthetic stratigraphic profiles created with a climate-driven model of ice and dust accumulation shows that this lower stratigraphic ratio is a natural consequence of time-variable ice accumulation rates.

The movement away from metals towards polymers for automobile bearing coatings opens a new area for the possible modification of these coatings. This project, done in collaboration with Castrol, was to understand adsorption of small molecules at the surface of these polymers and work towards engineering host-guest interactions at the surface to provide binding of specific molecules. Initially, the commercial polyamide-imide was characterised via Nuclear Magnetic Resonance (NMR), Infrared (IR) and Ultra-Violet/Visible (UV-Vis) spectroscopy to understand the nature of the functional groups and structures present. This revealed that the imidisation reaction was incomplete so the functionality within the polymer could change and thus alter how molecules interact with it. This reaction was then investigated via IR and NMR spectroscopy and it was shown that the degree of imidisation varied with temperature. Then the characterised polyamide-imide was used to study the adsorption of alkylphenols, a class of molecules that have structures and functionality like common additives used in engine oils. Additionally, the adsorption of water was studied as it is a common contaminant. These two systems were studied via solution depletion isotherms and neutron reflectivity measurements. The isotherms confirmed the adsorption of the molecules whilst neutron reflection was used to characterise the layers. For alkylphenol, a rather sparsely packed layer of the molecules and solvent existed at the surface with their alkyl tails extending into the solvent. For water; the molecules diffuse into the polyamide-imide. It can be partially removed by washing the surface with dry dodecane; however, some water remains in the polymer layer. A viologen-cucurbit[8]uril binding site was chosen as the supramolecular surface interaction. The binding unit was incorporated into the polyamide-imide. The synthesis of the binding site polymer was achieved in two stages; the reproduction of the commercial polymer and the synthesis of a polymer containing 100% viologen with and without threaded cucurbit[8]uril. Whilst the synthesis appeared successful, neutron reflectivity measurements showed that, when in contact with a solution containing a second guest, no adsorption was seen on the polymer containing cucurbit[8]uril. In order to study the supramolecular interaction in non-polar solvent, a series of rotaxanes were synthesised with viologen-cucurbit[8]uril cores and bulky stopper groups to prevent unthreading of the cucurbituril as well as enhancing the solubility of the system. The two components were linked via an amidisation reaction between an acid chloride and an amine. Due to the low solubility of the products confirmation of synthesis was only possible in one case. As well as using a viologen-cucurbit[8]uril binding site, binding in cucurbiturils via halogen bonding was investigated as common halogen bonding species show good solubility in non-polar solvents. Initially co-crystals of 2,5-diiodo-1,3,4,6-tetrafluorobenzene with tertiary amides were studied. With N,N-dimethylformamide, a 1:2 co-crystal was seen but the structure with N-methyl-2-pyrrolidone had a stoichiometry of 1:1. In both structures the oxygen of the amide is involved in a halogen bonding; however, for N-methyl-2-pyrrolidone it is bifurcated leading to the formation of chains. A 50-50 mixture of pyridine and formic acid was found to solubilize both halogen bond donors and cucurbit[n]uril. Over the course of these experiments the structure of the co-crystals of two halogen bond donors, 2,5-diiodo-1,3,4,6-tetrafluorobenzene and 2,4,6-triiodo-1,3,5-trifluorobenzene, with pyridine were determined. Crystals of the cucurbituril-adducts weren’t of sufficient quality to determine the structure. The presence of binding solution was confirmed by 1H and 19F NMR experiments on the methyliodide-cucurbit[6]uril and Trans-diiodooctrafluoroazobenzene-cucurbit[8]uril systems.

The objective of the proposed research is to extend the battery life in cellular handsets by improving the transmitter efficiency. Bandwidth efficient modulation formats, such as W-CDMA, encode much of the information in amplitude modulation. Therefore, linear transmitters must be used so as not to increase transmission errors, and cause interference in adjacent bands. Various engineering trade-offs were examined to find a suitable transmitter architecture for W-CDMA. Dynamic biasing of the transmitter power amplifier (PA) provides a simple way to improve efficiency for applications that require highly linear amplification. The envelope elimination and restoration (EER) PA or EER-based polar-modulated PA is an attractive solution since it has potential to achieve very high efficiency with high linearity. However, the major impediment to EER implementation has been the lack of power-efficient dynamic power supply circuits that can operate with sufficient modulation bandwidth, and simultaneously achieve the required modulation linearity. This work proposes several solutions to this problem. First, a dynamic supply circuit using delta modulation was designed and implemented. An open-loop EER PA with 48% peak efficiency was constructed and tested with a cellular band IS-95 CDMA signal with a bandwidth of 1.25 MHz. The low switching loss by using a delta modulator made the implementation of a wideband dynamic biasing circuit possible. Second, a dynamic supply circuit using dual-phase PWM was designed and implemented to achieve wider bandwidth, lower noise, and higher efficiency. An open-loop EER PA was implemented with the dynamic supply IC. A digital gain compensation scheme was developed to further increase bandwidth and linearity. This enables a dynamic supply circuit with lower switching frequency to have larger usable bandwidth with little increased power consumption. A cellular band W-CDMA voice signal was used to evaluate the performance of the overall PA. The PA achieved 50% efficiency while passing all required spectral specifications of W-CDMA standard. To increase the inherent low dynamic range of an EER PA, a dual-mode power amplifier combining an EER PA and power-level tracking PA was proposed. This work will contribute to the development of high efficiency, small-sized multi-mode linear PAs for battery-operated wireless handheld devices.

No description available.