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OQPSK Modulator Baseband

Modulation using OQPSK method

  • Library:
  • Communications System Toolbox / Modulation / Digital Baseband / PM

Description

The OQPSK Modulator Baseband block modulates the input signal using the offset quadrature phase shift keying (OQPSK) method and applies pulse shape filtering to the waveform. The output is a baseband representation of the modulated signal.

For information about delays incurred by modulator-demodulator pair processing, see Modulation Delays.

Ports

Input

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Input data, specified as an integer or bit column vector.

The input signal is processed based on the setting selected for Input type.

Data Types: double

Output

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Output baseband waveform, returned as a column vector of complex data.

Parameters

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Modulation

Input type, specified as Integer or Bit.

  • When you set Input type to Integer, the input can be a scalar value or column vector, the length of which is the number of input symbols.

  • When you set Input type to Bit, the input width must be an integer multiple of two.

The output sample period is the period of each integer or bit pair in the input divided by Samples per symbol.

Phase of zeroth point of constellation shifted from π/4 radians, specified as a scalar.

Signal constellation bit mapping, specified as Gray, Binary, or a custom 4-element numeric vector of integers with values from 0 to 3.

SettingConstellation MappingComment

Gray

The signal constellation mapping is a Gray-encoded integer.

Binary

The signal constellation mapping for the input integer m (0 ≤ m ≤ 3) is the complex value e(j*(PhaseOffset+π/4) + j*2*π*m/4).

Custom 4-element numeric vector of integers with values from 0 to 3

Elements [a b c d] must be composed of the set of values [0, 1, 2, 3] in any order.

Filtering

Select the filtering pulse shape: Half sine, Normal raised cosine, Root raised cosine, or Custom.

Raised cosine filter rolloff factor, specified as a scalar from 0 to 1.

Dependencies

This property appears when Pulse shape is Normal raised cosine or Root raised cosine.

Data Types: double

Filter length in symbols, specified as a scalar. An ideal raised cosine filter has an infinite impulse response. However, to realize a practical implementation of this filter, the object truncates the impulse response to Filter span (in symbols) symbols.

Dependencies

This property appears when Pulse shape is Normal raised cosine or Root raised cosine.

Data Types: double

Filter numerator, specified as a row vector.

Dependencies

This parameter appears when Pulse shape is Custom.

Data Types: double

Number of samples per symbol, specified as a positive even integer.

Data Types: double

Other Parameters

  • Enforce single-rate processing — Executes the model, ensuring that the input and output signals have the same port sample time. The block implements the rate change by making a size change at the output when compared to the input. For integer inputs, the output width equals Samples per symbol times the number of symbols.

    For more information, see Single-Rate Processing with OQPSK Modulator Block.

  • Allow multirate processing — Executes the model, allowing the input and output signals to have different port sample times. The output sample time equals the symbol period divided by Samples per symbol.

For more information, see Single-Rate Processing with OQPSK Modulator Block.

Select the output data type: double or single.

More About

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Introduced before R2006a

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