pammod
Pulse amplitude modulation (PAM)
Description
Examples
Modulate Data Symbols with PAM
Generate random data symbols and apply pulse amplitude modulation.
Set the modulation order.
M = 8;
Generate random integers and apply PAM modulation having an initial phase of /4.
data = randi([0 M-1],100,1); modData = pammod(data,M,pi/4);
Display the PAM constellation diagram.
scatterplot(modData)
PAM Symbol Mapping
Plot PAM symbol mapping for Gray-coded and binary-coded data.
Set the modulation order, and then create a data sequence containing a complete set of constellation points.
M = 8; data = 0:M-1;
Modulate and demodulate Gray and natural binary encoded data.
symgray = pammod(data,M,0,'gray'); mapgray = pamdemod(symgray,M,0,'gray'); symbin = pammod(data,M,0,'bin'); mapbin = pamdemod(symbin,M,0,'bin');
Plot the constellation points using one of the symbol sets. For each constellation point, assign a label indicating the Gray-coded and binary-coded values for each symbol.
For Gray-code symbol mapping, adjacent constellation points differ by a single bit and are not numerically sequential.
For binary-coded mapping, adjacent constellation points follow the binary encoding and are sequential.
scatterplot(symgray,1,0,'b*'); for k = 1:M text(real(symgray(k))-0.6,imag(symgray(k))+0.6,... dec2base(mapgray(k),2,4)); text(real(symgray(k))-0.2,imag(symgray(k))+1.2,... num2str(mapgray(k))); text(real(symbin(k))-0.6,imag(symbin(k))-0.6,... dec2base(mapbin(k),2,4),'Color',[1 0 0]); text(real(symbin(k))-0.2,imag(symbin(k))-1.2,... num2str(mapbin(k)),'Color',[1 0 0]); end axis([-M M -2 2])
Input Arguments
x
— Input signal
vector | matrix
Input signal, specified as a vector or matrix of integers in the range of [0,
M
– 1].
Example: randi([0 3],100,1)
Data Types: double
M
— Modulation order
positive integer power of two
Modulation order, specified as a positive integer power of two.
Example: 4
Data Types: double
initphase
— Initial phase
0
(default) | real-valued scalar | []
Initial phase of the modulated signal (in radians), specified as a real scalar.
Example: pi/4
Data Types: double
symorder
— Mapping order for modulation symbols
'bin'
(default) | 'gray'
Mapping order for the modulation symbols, specified as 'bin'
or
'gray'
. This argument specifies how the function assigns binary
vectors to corresponding integers.
If
symorder
is'bin'
, the function uses a binary-coded mapping order.If
symorder
is'gray'
, the function uses a Gray-coded mapping order.
Data Types: char
| string
Output Arguments
y
— Complex baseband representation of PAM-modulated signal
vector | matrix
Complex baseband representation of a PAM-modulated signal, returned as vector or
matrix of complex values. The modulated signal has a minimum Euclidean distance of 2.
The columns of y
represent independent channels.
Data Types: double
| single
Complex Number Support: Yes
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
See Code Generation for Complex Data with Zero-Valued Imaginary Parts (MATLAB Coder).
Version History
Introduced before R2006a
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