From e060704385701f8be42510dc465d6db57b3b07dd Mon Sep 17 00:00:00 2001
From: Marek Blok <Marek.Blok@pg.edu.pl>
Date: Tue, 4 Apr 2023 14:06:54 +0200
Subject: [PATCH] added QAM to DSP::u::SymbolMapper for even bits_per_symbol
---
CHANGELOG | 2 ++
src/cpp/DSP_modules2.cpp | 34 +++++++++++++++++++++++++++++++++-
src/include/DSP_lib.h | 2 +-
3 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/CHANGELOG b/CHANGELOG
index 341def6..258f559 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -8,6 +8,8 @@ TODO::
LAST DONE:
CHANGES:
+- ver. 0.20.021 - <b>2022.04.04</b> Added:
+ - DSP::u::SymbolMapper - experimental support for QAM for even bits_per_symbol (Gray ordering)
- ver. 0.20.020 - <b>2022.04.04</b> Fixed:
- DSP::u::SymbolMapper - fixed support for phase rotation of DSP::e::ModulationType::ASK constelation
- ver. 0.20.019 - <b>2022.03.30</b> Fixed:
diff --git a/src/cpp/DSP_modules2.cpp b/src/cpp/DSP_modules2.cpp
index 2b5d424..41702b7 100644
--- a/src/cpp/DSP_modules2.cpp
+++ b/src/cpp/DSP_modules2.cpp
@@ -1817,7 +1817,7 @@ unsigned int getConstellation(
break;
case DSP::e::ModulationType::ASK: {
- constellation.resize(M);
+ constellation.resize(M);
for (unsigned int n=0; n < M; n++) {
constellation[n].re = static_cast<DSP::Float>(n)/static_cast<DSP::Float>(M-1);
constellation[n].im = 0;
@@ -1834,6 +1834,38 @@ unsigned int getConstellation(
}
break;
+ case DSP::e::ModulationType::QAM: {
+ // to convert number into gray, take the number and perform XOR after shifting the number 1 bit to the right.
+ // x_gray = x ^ (x >> 1);
+ DSP::Float component_offset = (sqrt(DSP::Float(M))-1);
+ if ((bits_per_symbol % 2) == 0) {
+ unsigned int mask = 0x00;
+ for (unsigned int ind = 0; ind < bits_per_symbol/2; ind++) {
+ mask <<= 1;
+ mask += 1;
+ }
+ constellation.resize(M);
+ for (unsigned int n=0; n < M; n++) {
+ unsigned int x_gray = n ^ (n >> 1);
+ unsigned int i = x_gray & mask;
+ unsigned int q = (x_gray >> (bits_per_symbol/2));
+ q = q & mask;
+ constellation[n] = DSP::Complex(DSP::Float(i) - component_offset, DSP::Float(q) - component_offset);
+ }
+ if (constellation_phase_offset != 0.0) {
+ for (unsigned int ind=0; ind < M; ind++) {
+ constellation[ind] = constellation[ind] * DSP::Complex(cos(constellation_phase_offset), sin(constellation_phase_offset));
+ }
+ }
+ is_real = false;
+ }
+ else {
+ //! \TODO for odd bits_per_symbol generate QAM constellation for bits_per_symbol+1 and next remove half of the symbols with larger magnitude ???
+ DSP::log << DSP::e::LogMode::Error << "getConstellation" << DSP::e::LogMode::second << "Unsupported modulation QAM bits_per_symbol value " << endl;
+ }
+ }
+ break;
+
default:
DSP::log << DSP::e::LogMode::Error << "getConstellation" << DSP::e::LogMode::second << "Unsupported modulation type" << endl;
break;
diff --git a/src/include/DSP_lib.h b/src/include/DSP_lib.h
index 9ff7484..34d7894 100644
--- a/src/include/DSP_lib.h
+++ b/src/include/DSP_lib.h
@@ -11,7 +11,7 @@
#define DSP_VER_MAJOR 0
#define DSP_VER_MINOR 20
-#define DSP_VER_BUILD 20 // !!! without zeroes before, else this will be treated as octal number
+#define DSP_VER_BUILD 21 // !!! without zeroes before, else this will be treated as octal number
#define DSP_VER_YEAR 2023
#define DSP_VER DSP_VER_MAJOR.DSP_VER_MINOR.DSP_VER_BUILD
--
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