Polyphase FIR interpolator

The `dsp.FIRInterpolator`

System
object™ upsamples an input by the integer upsampling factor, *L*,
followed by an FIR anti-imaging filter. The filter coefficients are scaled by the
interpolation factor. A polyphase interpolation structure implements the filter. The resulting
discrete-time signal has a sampling rate *L* times the original sampling
rate.

To upsample an input:

Create the

`dsp.FIRInterpolator`

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).

`firinterp = dsp.FIRInterpolator`

`firinterp = dsp.FIRInterpolator(interpFactor,num)`

`firinterp = dsp.FIRInterpolator(___,Name,Value)`

returns an
FIR interpolator, `firinterp`

= dsp.FIRInterpolator`firinterp`

, which upsamples an input signal by a factor
of 3 and applies an FIR filter to interpolate the output.

returns an FIR interpolator with the integer-valued
`firinterp`

= dsp.FIRInterpolator(`interpFactor`

,`num`

)`InterpolationFactor`

property set to
`interpFactor`

and the `Numerator`

property set to
`num`

.

returns an FIR interpolator 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.`firinterp`

= dsp.FIRInterpolator(___,`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 = firinterp(x)`

`y = firinterp(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 Interpolation block reference page. The object properties correspond to the block parameters, except:

The

`FIRInterpolator`

object does not have a property that corresponds to the**Input processing**parameter of the FIR Interpolation block.The

**Rate options**block parameter is not supported by the`FIRInterpolator`

object.