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Deep seismic exploration in the Gippsland Basin is hindered by strong, unidentified noise below the Latrobe Group coal sequence. Low velocity events that appeared in field data semblance analyses suggested that an elastic wave modelling study was required to understand the subcoal reflection response. The modified reflectivity method (Kennet, 1980) provided a means for constructing detailed and accurate synthetic seismograms from realistic depth models, under the assumption of an isotropic, plane-layered earth. A study into the effect of each part of an elastic depth model (upon an elastic depth model (upon an elastic synthetic seismogram) resulted in a set of guidelines for obtaining a field data comparison. Excellent ties were obtained at several wells, often using little more than a partial sonic log. The noise contributions to the synthesis were interpreted using additional synthetics computed from variations upon the depth model and by exercising control over the wave types modelled. Subsequent processing of the synthetics revealed three types of persistent noise in progressively deeper parts of the subcoal image: 1) mode converted interbed multiples (generated within the coal sequence); 2) S-wave reflections and long period multiples (generated between the coal sequence and the Miocene carbonates and 3) surface related multiples.

Deep seismic exploration in the Gippsland Basin is hindered by strong, unidentified noise below the Latrobe Group coal sequence. Low velocity events that appeared in field data semblance analyses suggested that an elastic wave modelling study was required to understand the subcoal reflection response. The modified reflectivity method (Kennet, 1980) provided a means for constructing detailed and accurate synthetic seismograms from realistic depth models, under the assumption of an isotropic, plane-layered earth. A study into the effect of each part of an elastic depth model (upon an elastic depth model (upon an elastic synthetic seismogram) resulted in a set of guidelines for obtaining a field data comparison. Excellent ties were obtained at several wells, often using little more than a partial sonic log. The noise contributions to the synthesis were interpreted using additional synthetics computed from variations upon the depth model and by exercising control over the wave types modelled. Subsequent processing of the synthetics revealed three types of persistent noise in progressively deeper parts of the subcoal image: 1) mode converted interbed multiples (generated within the coal sequence); 2) S-wave reflections and long period multiples (generated between the coal sequence and the Miocene carbonates and 3) surface related multiples.

No description available.

With the evolution of technologies, mixed-signal system integration is becoming necessary for combining heterogeneous functions such as high-speed processors, radio frequency (RF) circuits, memory, microelectromechanical systems (MEMS), sensors, and optoelectronic devices. This kind of integration is required for convergent microsystems that support communication and computing capabilities in a tightly integrated module. A major bottleneck with such heterogeneous integration is the noise coupling between the dissimilar blocks constituting the system. The noise generated by the high-speed digital circuits can couple through the power distribution network (PDN) and this noise can transfer to sensitive RF circuits, completely destroying the functionality of noise-sensitive RF circuits. One common method used for mixed-signal integration in the package is splitting the power and/or ground planes. The gap in the power and ground planes can partially block the propagation of electromagnetic waves. However, electromagnetic energy can still couple through the split, especially at frequencies greater than 1 GHz. The AI-EBG structure in this dissertation has been developed to suppress unwanted noise coupling in mixed-signal systems and this AI- EBG structure shows excellent isolation (-80 dB ~ -140 dB), which results in a noise coupling-free environment in mixed-signal systems. The AI-EBG structure would be part of the power distribution network (PDN) in systems and is expected to have a significant impact on noise suppression and isolation in mixed-signal systems in future.

Speech enhancement has been an active research problem for decades and continues to be an important problem. This is made even more true by the proliferation of portable devices having audio input capabilities. In the presence of noise, both the quality and intelligibility of speech signals have been significantly deteriorated. The proposed research are the frameworks for improving the quality/intelligibility of the degraded speech: 1) a single-channel noise suppression system based on perceptual speech detection 2) multi-sensor noise suppression system for acoustic harsh environments based on non-air conductive sensors 3) a speech bandwidth extension system for telephone speech Significant improvement in both speech intelligibility and quality from the proposed frameworks are indicated from extensive experiments, inlcuding MOS, DRT, speech recognition task, and log spectral distortion.

This thesis is composed of three parts. In the first part, analysis and discussion of phase noise in phase-locked loop is made. Because OFDM upconverter requires high phase noise performance, we therefore study the mechanism of noise suppression in a proposed dual phase-locked loop, and then derive the formula to predict the circuit characteristics. In the second part, experiment and simulation of a dual phase-locked loop is performed for comparison. The experiment uses hybrid circuit combined with related equipment and components to measure the noise suppression characteristics in a dual phase-locked loop. The simulation relies on the component behavioral model in ADS. Comparison between simulation and measurement shows good agreement. In the third part, this thesis carries out a 1.55¡V2.3 GHz frequency synthesizer RFIC design for DVB up-down architecture using TSMC 0.18£gm CMOS process. The test results validate the chip design.

Este trabalho tem a finalidade de apresentar e comparar técnicas de redução de ruído utilizando como critérios de avaliação a mínima distorção espectral e a redução de ruído, na reconstrução dos sinais de voz degradados por ruído. Para tanto, utilizou-se os filtros de Kalman de tempo discreto e de freqüência discreta em conjunto com a técnica de subtração espectral de potência. Os sinais utilizados foram contaminados por ruídos branco e colorido, e a avaliação do desempenho dos algoritmos foi realizada tendo-se como parâmetros a relação sinal/ruído segmentada (SNRseg) e a distância de Itakura-Saito (d(a,b)). Após o processamento, verificou-se que a técnica, proposta neste trabalho, de filtragem de Kalman no tempo em conjunto com a subtração espectral de potência, apresentou resultados um pouco melhores em relação à filtragem de Kalman na freqüência em conjunto com a subtração espectral de potência. / This work has as main objective to present and to compare techniques of noise reduction using as evaluation criterion the low spectral distortion and the noise reduction in the reconstruction of corrupted speech signals. For so much, it was used the Kalman\'s filters in the time and frequency domain together with the technique of power spectral subtraction. The used signals were corrupted by white and colored noises and the evaluation of effectiveness of the algorithms was accomplished using the segmental signal-to-noise ratio (SNRseg) and the Itakura-Saito distance (d(a,b)). After the processing, it was noticed that the Kalman filtering in the time together with power spectral subtraction presented better results than the Kalman filtering in the frequency together with power spectral subtraction.