# comm.OQPSKModulator System object

Package: comm

Modulate using OQPSK method

## Description

The `OQPSKModulator` object modulates using the offset quadrature phase shift keying method. The output is a baseband representation of the modulated signal.

To modulate a signal using offset quadrature phase shift keying:

1. Define and set up your OQPSK modulator object. See Construction.

2. Call `step` to modulate the signal according to the properties of `comm.OQPSKModulator`. The behavior of `step` is specific to each object in the toolbox.

## Construction

`H = comm.OQPSKModulator` creates a modulator System object™, `H`. This object modulates the input signal using the offset quadrature phase shift keying (OQPSK) method.

`H = comm.OQPSKModulator(Name,Value)` creates an OQPSK modulator object, `H`, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (`Name1`,`Value1`,...,`NameN`,`ValueN`).

`H = comm.OQPSKModulator(PHASE,Name,Value)` creates an OQPSK modulator object, `H`. This object has the `PhaseOffset` property set to `PHASE` and the other specified properties set to the specified values.

## Properties

 `PhaseOffset` Phase of zeroth point of constellation from $\pi }{4}$ Specify the phase offset of the zeroth point of the constellation shifted from $\pi }{4}$, in radians, as a finite, real-valued scalar. The default is `0`. `BitInput` Assume input is bits Specify whether the input is bits or integers. The default is `false`. When you set this property to `true`, the inputs are bit representations of integers between `0` and `3`. The input requires a column vector of bit values with length that is an integer multiple of two. When you set this property to `false`, the input requires a column vector of integer values between `0` and `3`. `OutputDataType` Data type of output Specify the output data type as `double` | `single` | `Custom`. The default is `double`.

## Methods

 clone Create OQPSK modulator object with same property values constellation Calculate or plot ideal signal constellation getNumInputs Number of expected inputs to step method getNumOutputs Number of outputs from step method isLocked Locked status for input attributes and nontunable properties release Allow property value and input characteristics changes reset Reset modulator state step Modulate using OQPSK method

## Examples

Modulate data using OQPSK, and visualize the modulated data in a scatter plot.

```% Create binary data for 1000, 2-bit symbols data = randi([0 1],2000,1); % Create an OQPSK modulator System object and accept bits as inputs and set a phase offset of pi/16 hModulator = comm.OQPSKModulator(pi/16,'BitInput',true); % Modulate and plot the data, ignore the first output symbol modData = step(hModulator, data); scatterplot(modData(2:end))```

## Algorithms

This object implements the algorithm, inputs, and outputs described on the OQPSK Modulator Baseband block reference page. The object properties correspond to the block parameters.