Modulate using M-ary PAM method
The PAMModulator object modulates using M-ary pulse amplitude modulation. The output is a baseband representation of the modulated signal. The M-ary number parameter, M, represents the number of points in the signal constellation and requires an even integer.
To modulate a signal using M-ary pulse amplitude modulation:
H = comm.PAMModulator creates a modulator System object™, H. This object modulates the input signal using the M-ary pulse amplitude modulation (M-PAM) method.
H = comm.PAMModulator(Name,Value) creates an M-PAM modulator object, 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.PAMModulator(M,Name,Value) creates an M-PAM modulator object, H. This object has the ModulationOrder property set to M and the other specified properties set to the specified values.
Number of points in signal constellation
Specify the number of points in the signal constellation as a positive, integer scalar value. The default is 4. When you set the BitInput property to false, ModulationOrder must be even. When you set the BitInput property to true, ModulationOrder must be an integer power of two.
Assume bit inputs
Specify whether the input is in bits or integers. The default is false.
When you set this property to true, the step method input requires a column vector of bit values whose length is an integer multiple of log2(ModulationOrder). This vector contains bit representations of integers between 0 and ModulationOrder–1.
When you set this property to false, the step method input must be a column vector of integer symbol values between 0 and ModulationOrder–1.
Specify how the object maps an integer or group of log2(ModulationOrder) input bits to the corresponding symbol as one of Binary | Gray. The default is Gray.
When you set this property to Gray, the object uses a Gray-encoded signal constellation.
When you set this property to Binary, the input integer m, between ModulationOrder-1) maps to the complex value 2m– ModulationOrder + 1.
Constellation normalization method
Specify the method used to normalize the signal constellation as one of Minimum distance between symbols | Average power | Peak power. The default is Minimum distance between symbols.
Minimum distance between symbols
Specify the distance between two nearest constellation points as a positive, real, numeric scalar value. The default is 2. This property applies when you set the NormalizationMethod property to Minimum distance between symbols.
Average power of constellation
Specify the average power of the symbols in the constellation as a positive, real, numeric scalar value. The default is 1. This property applies when you set the NormalizationMethod property to Average power.
Peak power of constellation
Specify the maximum power of the symbols in the constellation as a positive, real, numeric scalar value. The default is 1. This property applies when you set the NormalizationMethod property to Peak power.
Data type of output
Specify the output data type as one of double | single | Custom. The default is double.
|clone||Create PAM modulator object with same property values|
|constellation||Calculate or plot ideal signal constellation|
|getNumInputs||Number of expected inputs to step method|
|getNumOutputs||Number of outputs from step method|
|isLocked||Locked status for input attributes and nontunable properties|
|release||Allow property value and input characteristics changes|
|step||Modulate using M-ary PAM method|
Modulate data using 16-PAM modulation, and visualize the data in a scatter plot.
% Create binary data for 100, 4-bit symbols data = randi([0 1],400,1); % Create a 16-PAM modulator System object with bits as inputs and % Gray-coded signal constellation hModulator = comm.PAMModulator(16,'BitInput',true); % Modulate and plot the data modData = step(hModulator, data); constellation(hModulator)
This object implements the algorithm, inputs, and outputs described on the M-PAM Modulator Baseband block reference page. The object properties correspond to the block parameters.