Above, we found that, for any integer
which divides
, a sufficient condition for perfect reconstruction is
![]() |
(12.59) |
![]() |
(12.60) |
![]() |
(12.62) |
Thus, given any polyphase matrix
, we can attempt to compute
: If it is stable, we can use it to build a
perfect-reconstruction filter bank. However, if
is FIR,
will typically be IIR. In §11.5 below, we will look at
paraunitary filter banks, for which
is FIR and
paraunitary whenever
is.