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.