Application of Wigner Distribution to Analysis of Filter Characteristics and EEG Transient Properties
| Autor: | Ta-Jen Liu, 劉達人 |
|---|---|
| Rok vydání: | 1994 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 82 Time-frequency representation is a widely used method in the field of analyzing nonstationary signal. Wigner distribution (WD) is one of many representations capable of displaying energy density information on time-frequency plane. First of all, WD method and conventional method are applied to the analysis of filters' characteristics. According to those examples and results presented, we find that characteristics of signals and systems are better revealed with time-frequency distribution. Especially when transient, frequency-dependent characteristics are of interest, WD provides a useful tool to extract those features. Then, WVD and the concept of instantaneous frequency (IF) are used to detect transient events of focal sharp waves in EEG. We will compare the results obtained with WVD method and STFT method. The performance using WVD is better than using STFT method. The performance is evaluated by the capability of correctly detecting the events of interest. In addition, channel correlation and spatial characteristics of multichannel EEG's are studied using WVD method with the aid of IF estimation. We find that there are two important factors in detecting the transient events of multichannel EEG's. One factor is the window length used for computing WVD and STFT. The other factor is the recording site of the signal. Based on our experiments, an appropriate choice of the EEG channel is the one close to the source generating the events. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|