comm.GeneralQAMModulator
Modulate using arbitrary QAM constellation
Description
The comm.GeneralQAMModulator
object modulates using quadrature amplitude modulation. The
output is a baseband representation of the modulated signal.
This object accepts variable-size inputs. After the object is locked, you can change the size of each input channel, but you cannot change the number of channels. For more information, see Variable-Size Signal Support with System Objects.
To modulate a signal using quadrature amplitude modulation:
Define and set up your QAM modulator object. See Construction.
Call
step
to modulate a signal according to the properties ofcomm.GeneralQAMModulator
. The behavior ofstep
is specific to each object in the toolbox.
Note
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.
Construction
H = comm.GeneralQAMModulator
creates a
modulator System object, H
. This object modulates
the input signal using a general quadrature amplitude modulation (QAM)
method.
H = comm.GeneralQAMModulator(
creates
a QAM modulator object, Name
,Value
)H
, with each specified
property set to the specified value. You can specify additional name-value
pair arguments in any order as (Name1
,Value1
,...,NameN
,ValueN
).
H = comm.GeneralQAMModulator(CONST,
creates
a General QAM modulator object, Name
,Value
)H
. This object
has the Constellation
property set to CONST
,
and the other specified properties set to the specified values.
Properties
|
Signal constellation Specify the constellation points as a vector of real or complex
double-precision data type. The default is exp().
The length of the vector determines the modulation order. The |
|
Data type of output Specify the output data type as one of |
Methods
step | Modulate using arbitrary QAM constellation |
Common to All System Objects | |
---|---|
release | Allow System object property value changes |
Examples
Modulate data using an arbitrary 3-point constellation. Then, visualize the data in a scatter plot
hQAMMod = comm.GeneralQAMModulator; % Setup a three point constellation hQAMMod.Constellation = [1 1i -1]; data = randi([0 2],100,1); modData = step(hQAMMod, data); scatterplot(modData)
Algorithms
This object implements the algorithm, inputs, and outputs described on the General QAM Modulator Baseband block reference page. The object properties correspond to the block parameters.
Extended Capabilities
Version History
Introduced in R2012a