# dpskmod

Differential phase shift keying modulation

## Syntax

``y = dpskmod(x,M)``
``y = dpskmod(x,M,phaserot)``
``y = dpskmod(x,M,phaserot,symorder)``

## Description

example

````y = dpskmod(x,M)` modulates the input signal using differential phase shift keying (DPSK) with modulation order `M`.```
````y = dpskmod(x,M,phaserot)` specifies the phase rotation of the DPSK modulation.```
````y = dpskmod(x,M,phaserot,symorder)` also specifies the symbol order.```

## Examples

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Plot the output of the `dspkmod` function to view the possible transitions between DPSK symbols.

Set the modulation order to 4 to model DQPSK modulation.

`M = 4;`

Generate a sequence of 4-ary random symbols.

`x = randi([0 M-1],500,1);`

Apply DQPSK modulation to the input symbols.

`y = dpskmod(x,M,pi/8);`

Specify a constellation diagram object to display a signal trajectory diagram and without displaying the corresponding reference constellation. Display the trajectory.

```cd = comm.ConstellationDiagram( ... ShowTrajectory=true, ... ShowReferenceConstellation=false); cd(y)```

## Input Arguments

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Input signal, specified as a vector or matrix of positive integers. The elements of `x` must have values in the range of [0, `M` – 1].

Data Types: `double`

Modulation order, specified as an integer power of two.

Example: `2` | `4` | `16`

Data Types: `double`

Phase rotation of the DPSK modulation, specified in radians as a real scalar. The total phase shift per symbol is the sum of `phaserot` and the phase generated by the differential modulation.

If you specify `phaserot` as empty, then `dpskmod` uses a phase rotation of 0 degrees.

Example: `pi/4`

Data Types: `double`

Symbol order, specified as `'bin'` or `'gray'`. This argument specifies how the function assigns binary vectors to corresponding integers.

• If `symorder` is `'bin'`, the function uses binary-coded ordering.

• If `symorder` is `'gray'`, the function uses a Gray-coded ordering.

Data Types: `char`

## Output Arguments

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Complex baseband representation of a DPSK-modulated output signal, returned as vector or matrix of complex values. The columns represent independent channels.

Note

An initial phase rotation of 0 is used in determining the first element of the output `y` (or the first row of `y` if it is a matrix with multiple rows), because two successive elements are required for a differential algorithm.

## Version History

Introduced before R2006a