Analysis of amplitude and phase characteristics for
delta, theta, and alpha bands at localized time instant from EEG
signals is important for the characterizing information processing in
the brain. In this paper, complex demodulation method was used to
analyze EEG (Electroencephalographic) signal, particularly for
auditory evoked potential response signal, with sufficient time
resolution and designated frequency bandwidth resolution required.
The complex demodulation decomposes raw EEG signal into 3
designated delta, theta, and alpha bands with complex EEG signal
representation at sampled time instant, which can enable the extraction
of amplitude envelope and phase information. Throughout simulated
test data, and real EEG signal acquired during auditory attention task,
it can extract the phase offset, phase and frequency changing instant
and decomposed amplitude envelope for delta, theta, and alpha bands.
The complex demodulation technique can be efficiently used in brain
signal analysis in case of phase, and amplitude information required.