System object: comm.QPSKDemodulator
Package: comm
Demodulate using QPSK method
Y = step(H,X)
Y = step(H,X,VAR)
Starting in R2016b, instead of using the step method to perform the operation defined by the System
object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.
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.
obj 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 (MATLAB) 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.