Modulate using Mary pulse amplitude modulation
AM, in Digital Baseband sublibrary of Modulation
The MPAM Modulator Baseband block modulates using Mary pulse amplitude modulation. The output is a baseband representation of the modulated signal. The Mary number parameter, M, is the number of points in the signal constellation. It must be an even integer.
All values of power assume a nominal impedance of 1 ohm.
Baseband Mary pulse amplitude modulation using the block's default signal constellation maps an integer m between 0 and M1 to the complex value
2m  M + 1
This value is actually a real number. The block's output signal is a complex datatype signal whose imaginary part is zero.
The block scales the default signal constellation based on how you set the Normalization method parameter. The following table lists the possible scaling conditions.
Value of Normalization Method Parameter  Scaling Condition 

Min. distance between symbols  The nearest pair of points in the constellation is separated by the value of the Minimum distance parameter 
Average Power  The average power of the symbols in the constellation is the Average power parameter 
Peak Power  The maximum power of the symbols in the constellation is the Peak power parameter 
This block accepts a scalar or column vector input signal.
When you set the Input type parameter to Integer
,
the block accepts integer values between 0
and M1
. M represents
the Mary number block parameter.
When you set the Input type parameter to Bit
,
the block accepts binaryvalued inputs that represent integers. The
block collects binaryvalued signals into groups of K =
log_{2}(M) bits
where
K represents the number of bits per symbol.
The input vector length must be an integer multiple of K. In this configuration, the block accepts a group of K bits and maps that group onto a symbol at the block output. The block outputs one modulated symbol for each group of K bits.
The Constellation ordering parameter indicates how the block assigns binary words to points of the signal constellation.
If Constellation ordering is
set to Binary
, then the block uses a natural
binarycoded constellation.
If Constellation ordering is
set to Gray
, then the block uses a Graycoded
constellation.
For details about the Gray coding, see the reference page for the MPSK Modulator Baseband block.
The MPAM Modulator Baseband block provides the capability to visualize a signal constellation from the block mask. This Constellation Visualization feature allows you to visualize a signal constellation for specific block parameters. For more information, see the Constellation Visualization section of the Communications System Toolbox™ User's Guide.
The number of points in the signal constellation. It must be an even integer.
Indicates whether the input consists of integers or groups of
bits. If this parameter is set to Bit
,
then the Mary number parameter must be 2^{K} for
some positive integer K.
Determines how the block maps each group of input bits to a corresponding integer.
Determines how the block scales the signal constellation. Choices
are Min. distance between symbols
, Average
Power
, and Peak Power
.
The distance between two nearest constellation points. This
field appears only when Normalization method is
set to Min. distance between symbols
.
The average power of the symbols in the constellation, referenced
to 1 ohm. This field appears only when Normalization method is
set to Average Power
.
The maximum power of the symbols in the constellation, referenced
to 1 ohm. This field appears only when Normalization method is
set to Peak Power
.
The output data type can be set to double
, single
, Fixedpoint
, Userdefined
,
or Inherit via back propagation
.
Setting this parameter to Fixedpoint
or Userdefined
enables
fields in which you can further specify details. Setting this parameter
to Inherit via back propagation
, sets the output
data type and scaling to match the following block.
Specify the word length, in bits, of the fixedpoint output
data type. This parameter is only visible when you select Fixedpoint
for
the Output data type parameter.
Specify any signed builtin or signed fixedpoint data type.
You can specify fixedpoint data types using the sfix
, sint
, sfrac
, and fixdt
functions
from FixedPoint
Designer™ software. This parameter is only visible
when you select Userdefined
for the Output
data type parameter.
Specify the scaling of the fixedpoint output by either of the following methods:
Choose Best precision
to
have the output scaling automatically set such that the output signal
has the best possible precision.
Choose Userdefined
to
specify the output scaling in the Output fraction length parameter.
This parameter is only visible when you select Fixedpoint
for
the Output data type parameter or when you select Userdefined
and
the specified output data type is a fixedpoint data type.
For fixedpoint output data types, specify the number of fractional
bits, or bits to the right of the binary point. This parameter is
only visible when you select Fixedpoint
or Userdefined
for
the Output data type parameter and Userdefined
for
the Set output fraction length to parameter.
Port  Supported Data Types 

Input 

Output 
