EngeeComms.DQPSK_ModulatorBaseband

Differential quadrature phase modulation.

Library	`EngeeComms`.
Block	DQPSK Modulator Baseband

Description

The DQPSK_ModulatorBaseband system object performs signal modulation with usage of the differential quadrature phase shift keying method. The output signal is a modulated signal in the baseband. The input signal must be sampled in time.

To modulate using the differential quadrature phase shift keying method, follow the steps below:

Create an object EngeeComms.DQPSK_ModulatorBaseband and set its properties.
Call the object with arguments as if it were a function.

To learn more about how to work with system objects, see Engee system objects.

Signals with an integer value

If the property InputType property is set to Integer, the allowed input values are 0, 1, 2 and 3. In this case, the system object accepts the input signal as a scalar or column vector.

If the first input signal is m, the modulated symbol at the output will be of the form: ,

where is the phase shift.

If the subsequent input signal is also m, then the modulated symbol at the output is equal to the previous modulated symbol multiplied by .

Signals with binary value

If the property InputType is set to Bit, then the input contains pairs of binary values. In this case, the system object accepts a column vector whose length is equal to an even integer.

More generally, if the property PhaseRotation is set to for some integer k, then the signal constellation has 2k points.

Syntax

Creation

dqpskmod = EngeeComms.DQPSK_ModulatorBaseband() creates a system object to perform modulation usage of the dqpskmod differential quadrature phase manipulation method with by default properties.

Example:
```
dqpskmod = EngeeComms.DQPSK_ModulatorBaseband()
```
dqpskmod = EngeeComms.DQPSK_ModulatorBaseband(Name=Value) creates a system object to perform modulation usage of the dqpskmod differential quadrature phase manipulation method with the specified Name property set to the specified Value value. You can specify additional arguments as a name-value pair in any order (Name1=Value1,…,NameN=ValueN).

Example:
```
dqpskmod = EngeeComms.DQPSK_ModulatorBaseband(InputType=Bit)
```

Usage

outsignal = dqpskmod(insignal) performs modulation of the input signal using the differential quadrature phase manipulation method as specified in dqpskmod. The result is returned in outsignal.

Arguments

Input arguments

In - input DQPSK modulated signal
scalar | vector

Details

The input DQPSK-modulated signal as a scalar or vector.

Data types

Float64

Output arguments

Out - demodulated signal
vector | scalar

Details

Demodulated signal in the form of a scalar or vector.

Data types

ComplexF64, ComplexF32

Properties

# PhaseRotation — phase rotation
Float64 real number

Details

The phase difference between the previous and current modulated symbols when the input is zero.

# InputType — input signal type
String

Details

Indicates whether the input signal consists of integers or bit pairs.

# ConstellationOrdering — order of signal constellations
String

Details

Determines how the system object maps each pair of input bits to the corresponding integer, using either the Binary or Gray scheme.

Methods

Common for all system objects

`step!`	Start the system object’s operating algorithm
`reset!`	Reset the internal states of the system object