Filtering and Downsampling, Revisited
Let's return to the example of §11.1.3, but
this time have the FIR lowpass filter h(n) be length
,
. In this case, the
polyphase filters,
, are
each length
.12.2 Recall that
![]() |
(12.15) |
leading to the result shown in Fig.11.11.
Next, we commute the
:
downsampler through the adders and
upsampled (stretched) polyphase filters
to obtain
Fig.11.12. Commuting the downsampler through the
subphase filters
to obtain
is an example of a
multirate noble identity.
Next Section:
Multirate Noble Identities
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Type II Polyphase Decomposition