Methods for time delay estimation between EEG signals : a critical evaluation
Three estimators of the time delay between signals, based on the methods of crosscorrelation, phase spectrum and an information theory-based method (AAMI), respectively, are critically evaluated. In some cases these methods can yield accurate measurements of the time delay between EEG channels, and can help to determine the location of an epileptic focus. The AAMI-based technique is efficient when a small number of data points is available, however, it requires large amounts of computer time, and its error analysis is not theoretically tractable. The other two methods provide theoretically tractable error analysis, and are comparatively faster. However, they require larger amounts of data. A good agreement with theory, as far as error is concerned, is achieved with the correlation and the phase spectrum-based method, provided that the number of equivalent degrees of freedom is large, the segment length is relatively large, and the normalized bandwidth of the signals is wide.