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 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 
