The Z-transform into control systems : review and a case of application

El presente documento describe el resultado de investigación de carácter exploratorio que condujo a estructurar una revisión categorizando y subcategorizando la transformada Z y sus aplicaciones en los sistemas de control. Para lo anterior, se usa el método por índices o basado en una taxonomía categórica orientada por fuentes clasificadas con las claves: historia, conceptualización, aplicación en señales elementales, criterios y características constructivas, y análisis y diseño en sistemas digitales; la metodología se valida por el juicio de expertos del grupo de investigación SciBas. Finalmente se desarrolla una aplicación en MatLab® simulando una implementación de un sistema de control. Como consecuencia se establece una línea de base de conocimiento para investigaciones sobre aplicaciones basadas en la transformada Z, y una forma de abordar simulaciones como alternativa de validación de resultados en un caso particular de sistemas de control.This document describes the result of an exploratory research that led to structuring a review categorizing and subcategorizing the Z transform and its applications in control systems. For the above, the method by indexes or based on a categorical taxonomy oriented by sources classified with the keys is used: history, conceptualization, application in elementary signals, criteria and constructive characteristics, and analysis and design in digital systems; the methodology is validated by the judgment of experts from the SciBas research group. Finally, an application is developed in MatLab® simulating an implementation of a control system. As a consequence, a knowledge base line is established for research on applications based on the Z transform, and a way of approaching simulations as an alternative to validate results in a particular case of control systems

GLOTTAL EXCITATION EXTRACTION OF VOICED SPEECH - JOINTLY PARAMETRIC AND NONPARAMETRIC APPROACHES

The goal of this dissertation is to develop methods to recover glottal flow pulses, which contain biometrical information about the speaker. The excitation information estimated from an observed speech utterance is modeled as the source of an inverse problem. Windowed linear prediction analysis and inverse filtering are first used to deconvolve the speech signal to obtain a rough estimate of glottal flow pulses. Linear prediction and its inverse filtering can largely eliminate the vocal-tract response which is usually modeled as infinite impulse response filter. Some remaining vocal-tract components that reside in the estimate after inverse filtering are next removed by maximum-phase and minimum-phase decomposition which is implemented by applying the complex cepstrum to the initial estimate of the glottal pulses. The additive and residual errors from inverse filtering can be suppressed by higher-order statistics which is the method used to calculate cepstrum representations. Some features directly provided by the glottal source\u27s cepstrum representation as well as fitting parameters for estimated pulses are used to form feature patterns that were applied to a minimum-distance classifier to realize a speaker identification system with very limited subjects

Zeros of Z-transform representation with application to source-filter separation in speech

International audienceWe propose a new spectral representation called the zeros of z-transform (ZZT), which is an all-zero representation of the z-transform of the signal. We show that separate patterns exist in ZZT representations of speech signals for the glottal flow and the vocal tract contributions. A decomposition method for source-tract separation is presented based on ZZT. The ZZT-decomposition consists in grouping the zeros into two sets, according to their location in the z-plane. This type of decomposition leads to separating glottal flow contribution (without a return phase) from vocal tract contribution in the z domain. Index Terms-Glottal flow estimation, source-filter separation, spectral representation, zeros of z-transform (ZZT)