| Sumario: | Some EEG signals possess pseudo-periodicity, which is difficult to identify and quantify. This paper points out the problems and proposes a straightforward approach for analyzing this long-term, extra low-rate rhythmicity (the fundamental frequency). The effect of pseudo periodicity on the Fourier spectrum is investigated. To process the enormous number of data points often encountered in this kind of signal, we adopt the down-sampling scheme in the field of multi-rate signal processing. In addition, waveform rectification is introduced to enhance the capability in detecting the number of pseudo periods. The experimental results demonstrate that the Fourier analysis, in combination with the down-sampling and amplitude-rectified processes, is feasible for quantifying the fundamental frequency and pseudo period of the EEG.
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