Detection of Instantaneous Frequency in EEG Using Phase Locked Loop（ＩＩ）

Abstract

In this thesis, we investigate the feasibility of the phase- locked-loop (PLL) circuit in detection of the instantaneous frequency of EEG (electroencephalograph) signals. The PLL has been successfully applied to the high-frequency and signal- component (at a given time instant) sinusoidal signals for the time-varying frequency tracking. However, the EEG is a low- frequency and multi-component signals. To adapt the PLL for tracking the time-varying frequency of EEG, we move the EEG frequency spectrum to a much higher frequency region by applying the single-sideband-modulation (SSB) to EEG. The performance of PLL in the low-frequency and high-frequency cases are studied and compared by the computer simulation and hardware implementation. Results of frequency detection via the hardware implementation of PLL are shown to be in agreement with which of computer simulation. The study shows that a modification of the PLL enables the detection of the time-varying frequency of EEG.