From 38bf7539f5629f5233281e342d11d1f64047c93c Mon Sep 17 00:00:00 2001
From: Markus Schmidl <markus.schmidl@mailbox.tu-dresden.de>
Date: Mon, 6 Jan 2025 14:18:31 +0100
Subject: [PATCH] add stub executable for testing channel estimation

---
 include/iq_stream_decoder.hpp          |  3 +++
 src/experiments/CMakeLists.txt         |  7 ++++++-
 src/experiments/channel_estimation.cpp | 15 +++++++++++++++
 src/iq_stream_decoder.cpp              |  6 +++---
 4 files changed, 27 insertions(+), 4 deletions(-)
 create mode 100644 src/experiments/channel_estimation.cpp

diff --git a/include/iq_stream_decoder.hpp b/include/iq_stream_decoder.hpp
index 3c03583..1e0d4af 100644
--- a/include/iq_stream_decoder.hpp
+++ b/include/iq_stream_decoder.hpp
@@ -41,6 +41,9 @@ class IQStreamDecoder {
     static void abs_convolve_same_length(const QueueT& queueA, std::size_t offsetA, const std::complex<float>* itb,
                                          std::size_t len, float* res);
 
+    static auto solve_channel(const std::vector<std::complex<float>>& pilots,
+                          const QueueT& signal_queue, const std::size_t signal_offset);
+
     std::vector<std::complex<float>> channel_estimation(std::vector<std::complex<float>> const& stream,
                                                         std::vector<std::complex<float>> const& pilots);
 
diff --git a/src/experiments/CMakeLists.txt b/src/experiments/CMakeLists.txt
index 91eaf0d..187853f 100644
--- a/src/experiments/CMakeLists.txt
+++ b/src/experiments/CMakeLists.txt
@@ -8,4 +8,9 @@ target_link_libraries(packet-parser-example tetra-decoder-library)
 add_executable(slots-parser-example
                src/experiments/slots_parser_example.cpp)
 
-target_link_libraries(slots-parser-example tetra-decoder-library)
\ No newline at end of file
+target_link_libraries(slots-parser-example tetra-decoder-library)
+
+add_executable(channel-estimation
+               src/experiments/channel_estimation.cpp)
+
+target_link_libraries(channel-estimation tetra-decoder-library)
\ No newline at end of file
diff --git a/src/experiments/channel_estimation.cpp b/src/experiments/channel_estimation.cpp
new file mode 100644
index 0000000..2ce4aff
--- /dev/null
+++ b/src/experiments/channel_estimation.cpp
@@ -0,0 +1,15 @@
+/*
+ * Copyright (C) 2025 Transit Live Mapping Solutions
+ * All rights reserved.
+ *
+ * Authors:
+ *   Marenz Schmidl
+ */
+
+#include <iostream>
+
+auto main(int argc, char** argv) -> int {
+    auto decoder = IQStreamDecoder(nullptr, nullptr, nullptr, /*is_uplink=*/true);
+
+    return EXIT_SUCCESS;
+}
\ No newline at end of file
diff --git a/src/iq_stream_decoder.cpp b/src/iq_stream_decoder.cpp
index cb875f1..cf3ee9a 100644
--- a/src/iq_stream_decoder.cpp
+++ b/src/iq_stream_decoder.cpp
@@ -95,8 +95,8 @@ std::vector<std::complex<float>> IQStreamDecoder::channel_estimation(std::vector
     return stream;
 }
 
-static auto solve_channel(const std::vector<std::complex<float>>& pilots,
-                          const FixedQueue<std::complex<float>, 300>& signal_queue, const std::size_t signal_offset)
+ auto IQStreamDecoder::solve_channel(const std::vector<std::complex<float>>& pilots,
+                          const QueueT& signal_queue, const std::size_t signal_offset)
     -> arma::cx_fvec {
     auto arma_pilots = arma::cx_fvec(pilots);
     auto arma_signal = arma::cx_fvec(pilots.size());
@@ -104,7 +104,7 @@ static auto solve_channel(const std::vector<std::complex<float>>& pilots,
         arma_signal[i] = signal_queue[signal_offset + i];
     }
     auto arma_conj_pilots = arma::conj(arma_pilots);
-    auto h_vec = arma::solve(arma_conj_pilots * arma_pilots, arma_conj_pilots * arma::conj(arma_signal));
+    arma::cx_fvec h_vec = arma::solve(arma_conj_pilots.t() * arma_pilots, arma_conj_pilots.t() * arma::conj(arma_signal).t());
     return h_vec;
 }