Properties of Activity Index Extended by Higher-Order Moments

摘要

The activity index definition is based on Mahalanobis distance. As such, its implementation deploys second-order statistics. In multiple-input multiple-output (MIMO) models, it indicates the level of activity of individual input sources. In this paper, we study an extended definition of activity index, whereas second-order statistics are replaced by higher orders. We show experimentally that noise resistance at higher even orders increases. Although the influence of superimposed source activity also increases, which is disturbing, combinations of two or more activity indexes at different orders open deeper insights into the behaviour of input sources. This can be of considerable help when analysing and, in particular, decomposing compound MIMO output signals.