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DQPSK Demodulator Baseband - Demodulate DQPSK-modulated data

Library

PM, in Digital Baseband sublibrary of Modulation

Description

The DQPSK Demodulator Baseband block demodulates a signal that was modulated using the differential quaternary phase shift keying method. The input is a baseband representation of the modulated signal.

The input must be a discrete-time complex signal. The output depends on the phase difference between the current symbol and the previous symbol. The first integer (or binary pair, if the Output type parameter is set to Bit) in the block's output is the initial condition of zero because there is no previous symbol.

The input can be either a scalar or a frame-based column vector. The block accepts the input data types single and double.

Outputs and Constellation Types

If the Output type parameter is set to Integer, then the block maps a phase difference of

θ + πm/2

to m, where θ is the Phase rotation parameter and m is 0, 1, 2, or 3.

If the Output type parameter is set to Bit, then the output contains pairs of binary values. The reference page for theDQPSK Modulator Baseband block shows which phase differences map to each binary pair, for the cases when the Constellation ordering parameter is either Binary or Gray.

Dialog Box

Output type

Determines whether the output consists of integers or pairs of bits.

Constellation ordering

Determines how the block maps each integer to a pair of output bits. This field is active only when Output type is set to Bit.

Phase rotation (rad)

This phase difference between the current and previous modulated symbols results in an output of zero.

Output data type

When the parameter is set to 'Inherit via internal rule' (default setting), the block will inherit the output data type from the input port. The output data type will be the same as the input data type if the input is of type single or double.

For integer outputs, this block can output the data types int8, uint8, int16, uint16, int32, uint32, single, and double. For bit outputs, output can be int8, uint8, int16, uint16, int32, uint32, boolean, single, or double.

Pair Block

DQPSK Modulator Baseband