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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.
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