Blind source separation in the presence of weak sources

We investigate the information processing of a linear mixture of independen t sources of different magnitudes. In particular we consider the case where a number m of the sources can be considered as "strong" as compared to the other ones, the "weak" sources. We find that it is preferable to perform b lind source separation in the space spanned by the strong sources, and that this can be easily done by first projecting the signal onto the m largest principal components. We illustrate the analytical results with numerical s imulations. (C) 2000 Elsevier Science Ltd. All rights reserved.