Upsample, filter, and downsample input signals
DSP System Toolbox / Filtering / Multirate Filters
The FIR Rate Conversion block resamples the discretetime input such that its sample period is K/L times the input sample period (T_{si}). K is the integer value you specify for the Decimation factor parameter, and L is the integer value you specify for the Interpolation factor parameter.
The block treats each column of the input as a separate channel and resamples the data in each channel independently over time. To do so, the block implements a polyphase filter structure and performs the following operations:
Upsamples the input to a higher rate by inserting
L−1
zeros between input
samples.
Passes the upsampled data through a directform II transpose FIR filter.
Downsamples the filtered data to a lower rate by discarding
K1
consecutive samples following each
sample that the block retains.
The polyphase filter implementation is more efficient than a straightforward upsamplefilterdecimate algorithm. See Orfanidis [1] for more information.
Data Types 

Direct Feedthrough 

Multidimensional Signals 

VariableSize Signals 

ZeroCrossing Detection 

[1] Orfanidis, Sophocles J. Introduction to Signal Processing. Upper Saddle River, NJ: PrenticeHall, 1996.
firceqrip
 firgr
 firhalfband
 firnyquist
dsp.CICCompensationDecimator
 dsp.CICCompensationInterpolator
 dsp.FIRDecimator
 dsp.FIRHalfbandDecimator
 dsp.FIRHalfbandInterpolator
 dsp.FIRInterpolator