Fine tune demodulator to OpenRTX M17 baseband

Fine tuned M17 demodulator with code generated from OpenRTX itself. TG-81
2021-12-26 15:42:41 +01:00 · 2021-12-26 15:42:41 +01:00 · 5bf4df75ba
commit 5bf4df75ba
--- a/openrtx/include/protocols/M17/M17Demodulator.h
+++ b/openrtx/include/protocols/M17/M17Demodulator.h
@ -106,8 +106,8 @@ private:
    static constexpr size_t M17_SAMPLES_PER_SYMBOL = M17_SPS;
    static constexpr size_t M17_INPUT_BUF_SIZE     = M17_FRAME_SAMPLES_24K / 2;
    static constexpr size_t M17_FRAME_BYTES        = M17_FRAME_SYMBOLS / 4;
-    static constexpr float conv_stats_alpha        = 0.0009765625f;
-    static constexpr float conv_threshold_factor   = 3.65;
+    static constexpr float conv_stats_alpha        = 0.0001f;
+    static constexpr float conv_threshold_factor   = 3.70;
    static constexpr float qnt_maxmin_alpha        = 0.999f;

    /**
--- a/openrtx/src/protocols/M17/M17Demodulator.cpp
+++ b/openrtx/src/protocols/M17/M17Demodulator.cpp
@ -84,7 +84,7 @@ void M17Demodulator::stopBasebandSampling()

 void M17Demodulator::resetCorrelationStats() {
    conv_ema = 0.0f;
-    conv_emvar = 1000000000.0f;
+    conv_emvar = 20000000000.0f;
 }

 /**
@ -204,7 +204,7 @@ void M17Demodulator::update()
        for(size_t i = 0; i < baseband.len; i++)
        {
            float elem = static_cast< float >(baseband.data[i]);
-            baseband.data[i] = static_cast< int16_t >(M17::rrc(elem) * 0.10);
+            baseband.data[i] = static_cast< int16_t >(M17::rrc(elem));
        }

        // If we locked a syncword just demodulate samples
--- a/scripts/plot_m17_demod_csv.py
+++ b/scripts/plot_m17_demod_csv.py
@ -2,9 +2,11 @@

 import pandas as pd
 from matplotlib import pyplot as plt
+from sys import argv

 plt.rcParams["figure.autolayout"] = True
-df = pd.read_csv("./build_linux/M17_demodulator_output_1.csv")
+df = pd.read_csv(argv[1])
+#df = df.head(n=10000)
 print("Contents in csv file:\n", df)
 #plt.plot(df.index, df.Input)
 #plt.plot(df.index, df.RRCSignal)
--- a/scripts/plot_m17_demod_csv2.py
+++ b/scripts/plot_m17_demod_csv2.py
@ -2,9 +2,11 @@

 import pandas as pd
 from matplotlib import pyplot as plt
+from sys import argv

 plt.rcParams["figure.autolayout"] = True
-df = pd.read_csv("./build_linux/M17_clock_recovery_output_2.csv")
+df = pd.read_csv(argv[1])
+#df = df.head(n=10000)
 print("Contents in csv file:\n", df)
 plt.plot(df.index, df.RRCSignal)
 plt.plot(df.index, df.SyncDetect)
--- a/tests/unit/M17_demodulator.cpp
+++ b/tests/unit/M17_demodulator.cpp
@ -83,11 +83,10 @@ int main()
    M17::M17Demodulator m17Demodulator = M17::M17Demodulator();
    m17Demodulator.init();
    dataBlock_t baseband = { nullptr, 0 };
-    baseband.data = baseband_buffer;
+    baseband.data = filtered_buffer;
    baseband.len = baseband_samples;
    dataBlock_t old_baseband = m17Demodulator.baseband;
    m17Demodulator.baseband = baseband;
-    baseband.data = filtered_buffer;

    FILE *output_csv_1 = fopen("M17_demodulator_output_1.csv", "w");
    fprintf(output_csv_1, "Input,RRCSignal,LSFConvolution,FrameConvolution,Stddev\n");
@ -109,7 +108,8 @@ int main()
                baseband.data[i],
                lsf_conv,
                stream_conv,
-                3.65 * m17Demodulator.getCorrelationStddev());
+                m17Demodulator.conv_threshold_factor *
+                m17Demodulator.getCorrelationStddev());
    }
    fclose(output_csv_1);

@ -126,6 +126,7 @@ int main()
        fscanf(syncword_ref, "%d\n", &expected_syncword);
        syncword = m17Demodulator.nextFrameSync(offset);
        offset = syncword.index + m17Demodulator.M17_SYNCWORD_SYMBOLS * M17_SPS;
+        //printf("%d\n", syncword.index);
        if (syncword.index != expected_syncword)
        {
            fprintf(stderr, "Error in syncwords detection #%d!\n", i);
--- a/tests/unit/assets/M17_test_baseband.raw
+++ b/tests/unit/assets/M17_test_baseband.raw
--- a/tests/unit/assets/M17_test_baseband_syncwords.txt
+++ b/tests/unit/assets/M17_test_baseband_syncwords.txt
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