QPSK Demodulator Baseband (Communications Blockset)

Demodulate QPSK-modulated data

Library

PM, in Digital Baseband sublibrary of Modulation

Description

The QPSK Demodulator Baseband block demodulates a signal that was modulated using the 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 input can be either a scalar or a frame-based column vector.

If the Output type parameter is set to Integer, then the block maps the point

to m, where is the Phase offset 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 the QPSK Modulator Baseband block shows the signal constellations for the cases when the Constellation ordering parameter is either Binary or Gray.

Processing an Upsampled Modulated Signal

The input signal can be an upsampled version of the modulated signal. The Samples per symbol parameter is the upsampling factor. It must be a positive integer.

For more information, see Upsampled Signals and Rate Changes in Using the Communications Blockset.

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 offset (rad): The phase of the zeroth point of the signal constellation.
Samples per symbol: The number of input samples that represent each modulated symbol.

Pair Block

QPSK Modulator Baseband

Puncture QPSK Modulator Baseband