Fig. 10.

(a) Amplitude spectrum (the reference level of amplitudes equals 1 V) of EEG signals recorded by the proposed instrument when the subject’s eyes are open and when they are closed. A high-performance commercial bioamplifier (Powerlab 26 T, ADInstruments) was also used as a reference instrument in this series of experiments. It is clear that in the 7.5–12.5 Hz band the amplitude spectrum of the EEG signals recorded when eyes are closed is significantly higher than the amplitude spectrum of the signals recorded when eyes are open. Furthermore, the results acquired using the wireless transmission method: 1) are in full agreement with the results acquired using the wired transmission method, and 2) are in full agreement with the results acquired using the commercial bioamplifier. (b) EEG spectrogram calculated from the EEG data wirelessly recorded by the proposed instrument. Alpha waves in the 7.5–12.5 Hz band during the eyes closed period are clearly visible