Assume that the signal
![$ f$](img137.png)
to be analyzed here is the superposition of
two signals,
![$ f=f_1+f_2$](img186.png)
, each component being produced by a different
phenomenon we want to discriminate. Let us assume further that
![$ f_1 \in {\cal{V}}$](img187.png)
and
![$ f_2 \in {\cal{W}^\bot}$](img188.png)
with
![$ {\cal{V}}$](img39.png)
and
![$ {\cal{W}^\bot}$](img166.png)
disjoint
subspaces.
Thus, we can obtain,
![$ f_1$](img7.png)
say, from
![$ f$](img137.png)
, by an oblique projector onto
![$ {\cal{V}}$](img39.png)
and along
![$ {\cal{W}^\bot}$](img166.png)
. The
projector will map to zero the component
![$ f_2$](img8.png)
to produce