
Multiple channels signals 95
FIGURE 3.5: Comparison of DTF (panel B) and PDC (panel D) for simulation
scheme A. Resulting schemes of propagation for DTF and PDC below corresponding
panels. Thickness of arrows proportional to the flow intensities. The convention of
presenting DTF/PDC is as in Figure 3.4. Note that the weak flow from channel 5 is
enhanced by PDC.
3.6 Multivariate signal decompositions
3.6.1 Principal component analysis (PCA)
3.6.1.1 Definition
Principal component analysis (PCA) is a method of decomposition of multichan-
nel epoched data into components that are linearly independent; that is, spatially and
temporally uncorrelated. Depending ...