This Figure shows the polyphase interpolation filter option which implements the computationally efficient 1-to- P interpolation filter.
A set of
N
prototype filter coefficients
is mapped to the
polyphase subfilters
according to
Equation 3-1
, as in the decimation case.
Each new input sample
engages all of the polyphase segments in parallel. For each input sample delivered to the filter,
output samples, one from each segment, are delivered to the filter output port, as indicated by the commutator in
This Figure
.
The output sample
rate is
where
is the sample rate of the input data stream
. Observe each of the polyphase segments operating at the low input sample rate
(compared to the high output sample rate
) and a total of
operations performed per output point.