OQPSK Demodulator Baseband (Communications Blockset)

Demodulate OQPSK-modulated data

Library

PM, in Digital Baseband sublibrary of Modulation

Description

The OQPSK Demodulator Baseband block demodulates a signal that was modulated using the offset quadrature 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 outputs integers between 0 and 3. If the Output type parameter is set to Bit, then the block outputs binary representations of such integers, in a binary-valued vector whose length is an even number.

The input symbol period is half the period of each output integer or bit pair. The constellation used to map bit pairs to symbols is on the reference page for the OQPSK Modulator Baseband block.

Frame-Based Inputs

If the input is a frame-based column vector, then the block processes several integers or several pairs of bits, in each time step. In this case, the output sample time equals the input sample time, even though the symbol period is half the output period.

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.

If the input is a frame-based column vector, then the output vector contains 1/(2S) integers or pairs of bits for each sample in the input vector, while the output sample time equals the input sample time.
If the input is a sample-based scalar, then the output vector contains a single integer or pair of bits, while the output sample time is 2S times the input sample time.

Dialog Box

Output type: Determines whether the output consists of integers or pairs of bits.
Phase offset (rad): The amount by which the phase of the zeroth point of the signal constellation is shifted from /4.
Samples per symbol: The number of input samples that represent each modulated symbol.

Pair Block

OQPSK Modulator Baseband

See Also

QPSK Demodulator Baseband

Multipath Rayleigh Fading Channel OQPSK Demodulator Passband