System object: comm.QPSKDemodulator
Package: comm

Demodulate using QPSK method


Y = step(H,X)
Y = step(H,X,VAR)


Y = step(H,X) demodulates input data, X, with the QPSK demodulator System object™, H, and returns Y. Input X must be a scalar or a column vector with double or single precision data type. When you set the BitOutput property to false, or when you set the DecisionMethod property to Hard decision and the BitOutput property to true, the data type of the input can also be signed integer, or signed fixed point (fi objects). Depending on the BitOutput property value, output Y can be integer or bit valued.

Y = step(H,X,VAR) uses soft decision demodulation and noise variance VAR. This syntax applies when you set the BitOutput property to true, the DecisionMethod property to Approximate log-likelihood ratioor Log-likelihood ratio, and the VarianceSource property to Input port. The data type of input VAR must be double or single precision.

    Note:   H specifies the System object on which to run this step method.

    The object performs an initialization the first time the step method is executed. This initialization locks nontunable properties and input specifications, such as dimensions, complexity, and data type of the input data. If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first call the release method to unlock the object.

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