Obtaining the EEG envelope in real time: a practical method based on homomorphic filtering.
A thorough study of the amplitude modulation characteristics of the EEG tracings remains to be done. In this paper a digital system is built in a way that permits real time elicitation of the EEG envelope, with a low computational effort. The EEG signal is considered to be the product of a slow varying envelope and a fast bipolar oscillation. The signal is applied to the input of a multiplicative homomorphic system which produces the envelope as its low-pass output. This method may then be the first step in a systematic on-line envelope analysis.
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Servicio de Neurofisiologia Clinica, Hospital General Vall d'Hebron, Barcelona, España.
D000328:Adult; D004569:Electroencephalography / Q000295:instrumentation*; D005071:Evoked Potentials; D006801:Humans; D009862:Online Systems / Q000295:instrumentation; D012815:Signal Processing, Computer-Assisted; D012984:Software