Polyphase FIR decimator

The `dsp.FIRDecimator`

System
object™ resamples vector or matrix inputs along the first dimension. The object
resamples at a rate *M* times slower than the input sampling rate, where
*M* is the integer-valued downsampling factor. The decimation combines an
FIR anti-aliasing filter with downsampling. The FIR decimator object uses a polyphase
implementation of the FIR filter.

To resample vector or matrix inputs along the first dimension:

Create the

`dsp.FIRDecimator`

object and set its properties.Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects? (MATLAB).

`firdecim = dsp.FIRDecimator`

`firdecim = dsp.FIRDecimator(decimFactor,num)`

`firdecim = dsp.FIRDecimator(___,Name,Value)`

returns an FIR
decimator, `firdecim`

= dsp.FIRDecimator`firdecim`

, which applies an FIR filter with a cutoff frequency
of `0.4*pi`

radians/sample to the input and downsamples the filter output
by factor of 2.

returns an FIR decimator with the integer-valued `firdecim`

= dsp.FIRDecimator(`decimFactor`

,`num`

)`DecimationFactor`

property set to `decimFactor`

and the `Numerator`

property set to `num`

.

returns an FIR decimator object with each specified property set to the specified value.
Enclose each property name in quotes. You can use this syntax with any previous input
argument combinations.`firdecim`

= dsp.FIRDecimator(___,`Name,Value`

)

**For versions earlier than R2016b, use the step
function to run the System object algorithm. The arguments to
step are the object you created, followed by
the arguments shown in this section.**

**For example, y = step(obj,x) and y = obj(x) perform equivalent operations.**

`y = firdecim(x)`

`y = firdecim(x,num)`

To use an object function, specify the
System
object as the first input argument. For
example, to release system resources of a System
object named `obj`

, use
this syntax:

release(obj)

This object implements the algorithm, inputs, and outputs described on the FIR Decimation block reference page. The object properties correspond to the block parameters, except:

**Framing**– The FIR decimator object only supports`Maintain input frame rate`

**Output buffer initial conditions**– The FIR decimator object does not support this parameter.**Rate options**– The FIR decimator object does not support this parameter.**Input processing**The FIR decimator object does not support this parameter.