# dsp.DigitalDownConverter

Translate digital signal from intermediate frequency (IF) band to baseband and decimate it

## Description

The `dsp.DigitalDownConverter`

object translates digital signal from
intermediate frequency (IF) band to baseband and decimates it.

To digitally downconvert the input signal:

Create the

`dsp.DigitalDownConverter`

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?

## Creation

### Description

returns a
digital downconverter (DDC) System object™, `dwnConv`

= dsp.DigitalDownConverter`dwnConv`

.

returns a DDC object, `dwnConv`

= dsp.DigitalDownConverter(`Name,Value`

)`dwnConv`

, with the specified property
`Name`

set to the specified `Value`

. You can
specify additional name-value pair arguments in any order as
(`Name1`

,`Value1`

,...,`NameN`

,`ValueN`

).

## Properties

## Usage

### Description

### Input Arguments

### Output Arguments

## Object Functions

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)

## Examples

## More About

## Algorithms

The digital down converter downconverts the input signal by multiplying it with a complex exponential that has the specified center frequency. The algorithm downsamples the frequency downconverted signal using a cascade of three decimation filters. In this case, the filter cascade consists of a CIC decimator, a CIC compensator, and a third FIR decimation stage. The following block diagram shows the architecture of the digital down converter.

The scaling section normalizes the CIC gain and the oscillator power. It can also contain a
correction factor to achieve the desired ripple specification. When you specify an
oscillator signal through the input port, the normalization factor does not include
the oscillator power factor. Depending on how you set the decimation factor, the
block bypasses the third filter stage. When the input data type is double or single,
the algorithm implements an *N*-section CIC decimation filter as an
FIR filter with a response that corresponds to a cascade of *N*
boxcar filters. The algorithm emulates a CIC filter with an FIR filter so that you
can run simulations with floating-point data. When the input data type is
fixed-point, the algorithm implements a true CIC filter with actual comb and
integrator sections.

This block diagram represents the DDC arithmetic with single or double-precision, floating-point inputs.

For details about fixed-point operation, see Fixed Point.

## Extended Capabilities

## Version History

**Introduced in R2012a**

## See Also

### Functions

`getDecimationFactors`

|`getFilterOrders`

|`getFilters`

|`fvtool`

|`groupDelay`

|`visualizeFilterStages`

|`generatehdl`