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PM, in Digital Baseband sublibrary of Modulation
The OQPSK Modulator Baseband block modulates using the offset quadrature phase shift keying method. The output is a baseband representation of the modulated signal.
If the Input type parameter is set to Integer, then valid input values are 0, 1, 2, and 3. In this case, the input can be either a scalar or a frame-based column vector.
If the Input type parameter is set to Bit, then the input must be a binary-valued vector. In this case, the input can be either a vector of length two or a frame-based column vector whose length is an even integer.
For integer inputs, the block can accept the data types int8, uint8, int16, uint16, int32, uint32, single, and double. For bit inputs, the block can accept int8, uint8, int16, uint16, int32, uint32, boolean, single, and double.
The symbol period is half the input period. The first output symbol is an initial condition of zero that is unrelated to the input values.
The constellation used to map bit pairs to symbols is in the following figure. If the block's Phase offset parameter is nonzero, then this constellation is rotated by that parameter value.
For sample-based inputs, the output sample time equals half of the input symbol period.
In bit input mode, the input must be of length two.
In integer input mode, the input must be a scalar value.
If the input is a sample-based scalar, then the block outputs a single integer symbol for each time step. In this case, the sample-based input symbol period is half the output symbol period.
To open the completed model, click here in the MATLAB Help browser
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 period of each output sample is half the period of each integer or bit pair in the input.
To open the completed model, click here in the MATLAB Help browser
The modulator-demodulator pair incurs a delay, as described in Delays in Digital Modulation.
The amount by which the phase of the zeroth point of the signal constellation is shifted from π/4.
Indicates whether the input consists of integers or pairs of bits.
The output data type can be set to double, single, Fixed-point, User-defined, or Inherit via back propagation.
Setting this parameter to Fixed-point or User-defined enables fields in which you can further specify details. Setting this parameter to Inherit via back propagation, sets the output data type and scaling to match the following block.
Specify the word length, in bits, of the fixed-point output data type. This parameter is only visible when you select Fixed-point for the Output data type parameter.
Specify any signed built-in or signed fixed-point data type. You can specify fixed-point data types using the sfix, sint, sfrac, and fixdt functions from Simulink Fixed Point. This parameter is only visible when you select User-defined for the Output data type parameter.
Specify the scaling of the fixed-point output by either of the following methods:
Choose Best precision to have the output scaling automatically set such that the output signal has the best possible precision.
Choose User-defined to specify the output scaling in the Output fraction length parameter.
This parameter is only visible when you select Fixed-point for the Output data type parameter or when you select User-defined and the specified output data type is a fixed-point data type.
For fixed-point output data types, specify the number of fractional bits, or bits to the right of the binary point. This parameter is only visible when you select Fixed-point or User-defined for the Output data type parameter and User-defined for the Set output fraction length to parameter.
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