System object: comm.GeneralQAMDemodulator
Demodulate using arbitrary QAM constellation
Y = step(H,X)
Y = step(H,X,VAR)
Y = step(H,X) demodulates the input data, X, with the general QAM 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 true and the DecisionMethod property to 'Log-likelihood ratio' the input data type must be single or double precision. 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 ratio or Log-likelihood ratio, and the VarianceSource property to 'Input port'.
Note: 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.