QUT ePrints

Parameters selection for optimising time-frequency distributions and measurements of time-frequency characteristics of nonstationary signals

Sucic, Victor (2004) Parameters selection for optimising time-frequency distributions and measurements of time-frequency characteristics of nonstationary signals. PhD thesis, Queensland University of Technology.


The quadratic class of time-frequency distributions (TFDs) forms a set of tools which allow to effectively extract important information from a nonstationary signal. To determine which TFD best represents the given signal, it is a common practice to visually compare different TFDs' time-frequency plots, and select as best the TFD with the most appealing plot. This visual comparison is not only subjective, but also difficult and unreliable especially when signal components are closely-spaced in the time-frequency plane. To objectively compare TFDs, a quantitative performance measure should be used. Several measures of concentration/complexity have been proposed in the literature. However, those measures by being derived with certain theoretical assumptions about TFDs are generally not suitable for the TFD selection problem encountered in practical applications. The non-existence of practically-valuable measures for TFDs' resolution comparison, and hence the non-existence of methodologies for the signal optimal TFD selection, has significantly limited the use of time-frequency tools in practice. In this thesis, by extending and complementing the concept of spectral resolution to the case of nonstationary signals, and by redefining the set of TFDs' properties desirable for practical applications, we define an objective measure to quantify the quality of TFDs. This local measure of TFDs' resolution performance combines all important signal time-varying parameters, along with TFDs' characteristics that influence their resolution. Methodologies for automatically selecting a TFD which best suits a given signal, including real-life signals, are also developed. The optimisation of the resolution performances of TFDs, by modifying their kernel filter parameters to enhance the TFDs' resolution capabilities, is an important prerequisite in satisfying any additional application-specific requirements by the TFDs. The resolution performance measure and the accompanying TFDs' comparison criteria allow to improve procedures for designing high-resolution quadratic TFDs for practical time-frequency analysis. The separable kernel TFDs, designed in this way, are shown to best resolve closely-spaced components for various classes of synthetic and real-life signals that we have analysed.

Impact and interest:

Citation countsare sourced monthly from Scopus and Web of Science® citation databases.

These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.

Citations counts from the Google Scholar™ indexing service can be viewed at the linked Google Scholar™ search.

Full-text downloads:

684 since deposited on 03 Dec 2008
102 in the past twelve months

Full-text downloadsdisplays the total number of times this work’s files (e.g., a PDF) have been downloaded from QUT ePrints as well as the number of downloads in the previous 365 days. The count includes downloads for all files if a work has more than one.

ID Code: 15834
Item Type: QUT Thesis (PhD)
Supervisor: Boashash, Boualem& MacGillivray, Helen
Keywords: Time-frequency distribution, Quadratic Class of time-frequency distributions, nonstationary signal, monocomponent signal, multicomponent signal, frequency modulated (FM) signal, linear FM signal, non-linear FM signal, kernel filter, separable kernel, Fourier transform, crossterms, autoterms, concentration, resolution, mainlobe amplitude, sidelobe amplitude, instantaneous frequency, instantaneous bandwidth, crossterms amplitude, comparison criteria, performance measure, parameter optimisation, optimal time-frequency distribution, design requirements, additive white Gaussian noise, real-life signal, Modified B distribution, Smoothed windowed Wigner-Ville distribution, separable kernel TFD.
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Past > Schools > School of Engineering Systems
Department: Built Environment and Engineering
Institution: Queensland University of Technology
Deposited On: 03 Dec 2008 13:50
Last Modified: 29 Oct 2011 05:39

Export: EndNote | Dublin Core | BibTeX

Repository Staff Only: item control page