The symbol demapper takes constellation points and generates appropriate consecutive bits
Keywords
digital, electrical, unidirectional
Ports
| Name | Type |
|---|---|
| input I | Electrical Signal |
| input Q | Electrical Signal |
| output | Digital Signal |
Properties
General Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
name Defines the name of the element. |
Modulation Symbol Demapper | - | - |
|
annotate Defines whether or not to display annotations on the schematic editor. |
true | - | [true, false] |
|
enabled Defines whether or not the element is enabled. |
true | - | [true, false] |
|
type Defines the element unique type (read only). |
Modulation Symbol Demapper | - | - |
|
description A brief description of the elements functionality. |
The symbol demapper takes constellation points and generates appropriate consecutive bits | - | - |
|
prefix Defines the element name prefix. |
DEMAP | - | - |
|
model Defines the element model name. |
- | - | - |
|
library Defines the element location or source in the library (custom or design kit). |
- | - | - |
|
local path Defines the local path or working folder $LOCAL for the element. |
- | - | - |
|
url An optional URL address pointing to the element online help. |
- | - | - |
Standard Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
configuration Defines whether or not to enable I and Q ports. |
dual input | - | [dual input, single input |
|
bitrate Defines the input signal bitrate. |
%bitrate% | bits/s | [1, +∞) |
|
synchronization delay I The time delay to apply to the input signal. |
0 | s | [0, +∞) |
|
synchronization delay Q The time delay to apply to the input signal. |
0 | s | [0, +∞) |
|
decision method Defines the decision method. Methods include 'hard decision', 'log-likelihood ratio' and 'approximate log-likelihood ratio'. |
hard decision | - | [hard decision, log likelihood ratio, approximate log likelihood ratio |
|
noise variance I The noise variance or the noise power. |
0 | W | [0, +∞) |
|
noise variance Q The noise variance or the noise power. |
0 | W | [0, +∞) |
|
decision point Defines whether or not to automatically determine the decision point for the constellation diagram. |
automatic | - | [automatic, user defined |
|
decision instant Defines the time instant for the constellation diagram detection decision points. |
20e-012 | s | (-∞, +∞) |
|
scale factor I The scale factor for the symbol map IQ values. |
1 | - | (0, +∞) |
|
scale factor Q The scale factor for the symbol map IQ values. |
1 | - | (0, +∞) |
|
rotation The rotation angle rotates the symbol map IQ values. |
0 | rad | (-∞, +∞) |
|
load map from file Defines whether or not to load IQ values from an input file or to use the currently stored values. |
false | - | [true, false] |
|
symbol map filename The file containing user defined IQ values. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
modulation type Defines the input signal modulation scheme. The user can choose between different standard modulation schemes. |
2PAM | - | [user defined, 2PAM, 4PAM, 8PAM, 16PAM, BPSK, QPSK, 8PSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM, 256QAM |
|
symbol map table The table allows the user to read or modified a symbol map by changing the position of one or more symbols. |
<2,2> [-1, 1, 0,...] | - | - |
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Implementation Details
The modulation symbol demapper takes constellation points input and output appropriate consecutive bits accordingly. Please see the example file Demapper.icp for detailed information.
In this example, the modulation symbol map is used to generate 16QAM modulated electrical signals, and then the modulation symbol demapper demodulates the signals according to the modulation type selected.
If the demapper's modulation type matches the mapper's modulation type, the original transmitted signal should be recovered. The first figure below has matched demapper and mapper while the second has mismatch demapper and mapper, the results are shown.
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Fig. 1 Matched demapper & mapper |
Fig. 1 Not matched demapper & mapper |