# Documentation

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# step

System object: comm.OQPSKModulator
Package: comm

Modulate using OQPSK method

## Syntax

`Y = step(H,X)`

## Description

 Note:   Starting in R2016b, instead of using the `step` method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, `y = step(obj,x)` and `y = obj(x)` perform equivalent operations.

`Y = step(H,X)` modulates input data, `X`, with the OQPSK modulator object, `H`, and returns baseband modulated output, `Y`. Depending on the value of the `BitInput` property, input `X` can be an integer or bit valued column vector with numeric, logical, or fixed-point data types.

The OQPSK modulator object upsamples by a factor of two. The `step` method outputs the length, `Y`, as 2$×$N, where N is the length of the input, `X`. The `step` method outputs an initial condition of zero, which is unrelated to the input values.

 Note:   `H` specifies the System object on which to run this `step` method.The object performs an initialization the first time the `step` method is executed. This initialization locks nontunable properties and input specifications, such as dimensions, complexity, and data type of the input data. If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first call the `release` method to unlock the object.