The reference signals ECG and EOG and the corrupted EEG were acquired simultaneously in polysomnographic studies. EEG, ECG and EOG records belonged to five adult patients and were downloaded from the MIT-BIH Polysomnographic Databas-Physiobank [11]. For testing purposes, in case no real records were available, artificially generated signals are quite acceptable.
3. RESULTS
Five EEG records were filtered with the proposed adaptive cascade filter. As we mentioned above, the first stage attenuates the line-frequency artifact. The H1(z) filter adapts the amplitude and the phase of the artificial sinusoidal signal x1(n) (50 or 60 Hz) in order to have as output a replica, y1(n), of the linefrequency artifact present in the EEG. Figure 4 illustrates the power spectra of: (a) the original EEG with the 50 Hz interference, and (b) the first stage output e1(n). Note in the last one that this component is attenuated in e1(n) and there are not modifications in the EEG original spectrum in other frequencies.
The reference signals ECG and EOG and the corrupted EEG were acquired simultaneously in polysomnographic studies. EEG, ECG and EOG records belonged to five adult patients and were downloaded from the MIT-BIH Polysomnographic Databas-Physiobank [11]. For testing purposes, in case no real records were available, artificially generated signals are quite acceptable.
3. RESULTS
Five EEG records were filtered with the proposed adaptive cascade filter. As we mentioned above, the first stage attenuates the line-frequency artifact. The H1(z) filter adapts the amplitude and the phase of the artificial sinusoidal signal x1(n) (50 or 60 Hz) in order to have as output a replica, y1(n), of the linefrequency artifact present in the EEG. Figure 4 illustrates the power spectra of: (a) the original EEG with the 50 Hz interference, and (b) the first stage output e1(n). Note in the last one that this component is attenuated in e1(n) and there are not modifications in the EEG original spectrum in other frequencies.
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