afsk clock skew initial work

src/demodulators/afsk.cpp

@@ -9,6 +9,7 @@
 #include <algorithm>
 #include <cmath>
 #include <fstream>
+#include <iostream>
 
 #include "bit-stream.h"
 #include "demodulators.hpp"
@@ -74,8 +75,8 @@ void afskSignalToBaseBand(wavgen::Reader &wavgen_reader,
 
     double s1 = mark_i_integ * mark_i_integ + mark_q_integ * mark_q_integ;
     double s2 = space_i_integ * space_i_integ + space_q_integ * space_q_integ;
-    int result = s1 - s2;
-
+    double result = s1 - s2;
+    std::cout << result << " ";
     if (result > 0) {
       result = 1;
     } else {
@@ -125,13 +126,5 @@ bool demodulators::afskDecodeAscii(wavgen::Reader &wavgen_reader,
   afskBaseBandToBitStream(base_band_signal, bit_stream);
   message = afskBitStreamToAscii(bit_stream);
 
-  // bit_stream.dumpBitStreamAsHex();
-  // std::ofstream out_file("out.txt");
-  // for (double d : base_band_signal) {
-  //   std::clamp(d, 0.0, 1.0);
-  //   out_file << d << std::endl;
-  // }
-
-  (void)message;
   return false;
 }

tests/CMakeLists.txt

@@ -5,4 +5,6 @@ add_executable(mwav_unit_tests
   ${MWAV_TESTS}/afsk_ascii_test.cpp
 )
 target_link_libraries(mwav_unit_tests GTest::GTest GTest::Main MWavLib WavGen)
-target_include_directories(mwav_unit_tests PRIVATE)
+target_include_directories(mwav_unit_tests PRIVATE)
+
+configure_file(${MWAV_TESTS}/afsk_timing_skew.wav ${CMAKE_CURRENT_BINARY_DIR}/afsk_timing_skew.wav COPYONLY)

tests/afsk_ascii_test.cpp

@@ -4,20 +4,35 @@
 #include <data_modes.hpp>
 #include <wav_gen.hpp>
 
-const std::string kOutFilePath = "test.wav";
+const mwav::data::Mode kMode = mwav::data::Mode::AFSK1200;
 
+/**
+ * @brief Encodes a string into an AFSK1200 signal/WAV file and then decodes it.
+ */
 TEST(DataModulation, EncodeAndDecodeAsciiAFSK) {
-  mwav::data::Mode mode = mwav::data::Mode::AFSK1200;
-
-  std::string input = "UUUHello World!UUU\x04";
+  const std::string kOutFilePath = "test.wav";
+  std::string input = "Hello World!\x04";
   std::string output;
 
-  mwav::data::encodeString(mode, input, kOutFilePath);
-  mwav::data::decodeString(mode, kOutFilePath, output);
+  mwav::data::encodeString(kMode, input, kOutFilePath);
+  mwav::data::decodeString(kMode, kOutFilePath, output);
   EXPECT_STREQ(input.c_str(), output.c_str());
 
   wavgen::Reader reader(kOutFilePath);
   const auto total_samples = reader.getNumSamples();
   const auto minimum_samples = input.size() * 8;
   EXPECT_GE(total_samples, minimum_samples);
+}
+
+/**
+ * @brief Pre-prepared WAV file with 20 samples added to the start of the file.
+ * @details 20 samples is enough to throw the signal off by 1/2 of a bit. This
+ * should test the ability of the demodulator to sync to the signal.
+ */
+TEST(DataModulation, DecodeWithSignalSkew) {
+  const std::string kInputFile = "afsk_timing_skew.wav";
+  std::string output;
+  mwav::data::decodeString(kMode, kInputFile, output);
+
+  std::cout << output << std::endl;
 }