Replace RRC filter taps, update M17 testsuite

RRC filter taps have been replaced with the ones generated by Wojciech,
a new baseband for the M17 demodulation testsuite has been generated,
using OpenRTX itself and some further minor changes.

TG-81

openrtx/include/protocols/M17/M17DSP.h

@@ -36,7 +36,7 @@ namespace M17
 /*
  * Coefficients for M17 RRC filter
  */
-extern const std::array<float, 79> rrc_taps;
+extern const std::array<float, 81> rrc_taps;
 
 /*
  * FIR implementation of the RRC filter for baseband audio generation.

openrtx/src/protocols/M17/M17DSP.cpp

@@ -26,34 +26,34 @@ namespace M17
 /*
  * Coefficients for M17 RRC filter for 48KHz sample rate
  */
-const std::array<float, 79> rrc_taps = {
+const std::array<float, 81> rrc_taps = {
-    -0.009265784007800534,  -0.006136551625729697,  -0.001125978562075172,
+    -0.003195702904062073, -0.002930279157647190, -0.001940667871554463,
-     0.004891777252042491,   0.01071805138282269,    0.01505751553351295,
+    -0.000356087678023658, 0.001547011339077758,  0.003389554791179751,
-     0.01679337935001369,    0.015256245142156299,   0.01042830577908502,
+    0.004761898604225673,  0.005310860846138910,  0.004824746306020221,
-     0.003031522725559901,  -0.0055333532968188165, -0.013403099825723372,
+    0.003297923526848786,  0.000958710871218619,  -0.001749908029791816,
-     -0.018598682349642525, -0.01944761739590459,   -0.015005271935951746,
+    -0.004238694106631223, -0.005881783042101693, -0.006150256456781309,
-     -0.0053887880354343935, 0.008056525910253532,   0.022816244158307273,
+    -0.004745376707651645, -0.001704189656473565, 0.002547854551539951,
-     0.035513467692208076,   0.04244131815783876,    0.04025481153629372,
+    0.007215575568844704,  0.011231038205363532,  0.013421952197060707,
-     0.02671818654865632,    0.0013810216516704976, -0.03394615682795165,
+    0.012730475385624438,  0.008449554307303753,  0.000436744366018287,
-    -0.07502635967975885,   -0.11540977897637611,   -0.14703962203941534,
+    -0.010735380379191660, -0.023726883538258272, -0.036498030780605324,
-    -0.16119995609538576,   -0.14969512896336504,   -0.10610329539459686,
+    -0.046500883189991064, -0.050979050575999614, -0.047340680079891187,
-    -0.026921412469634916,   0.08757875030779196,    0.23293327870303457,
+    -0.033554880492651755, -0.008513823955725943, 0.027696543159614194,
-     0.4006012210123992,     0.5786324696325503,     0.7528286479934068,
+    0.073664520037517042,  0.126689053778116234,  0.182990955139333916,
-     0.908262741447522,      1.0309661131633199,     1.1095611856548013,
+    0.238080025892859704,  0.287235637987091563,  0.326040247765297220,
-     1.1366197723675815,     1.1095611856548013,     1.0309661131633199,
+    0.350895727088112619,  0.359452932027607974,  0.350895727088112619,
-     0.908262741447522,      0.7528286479934068,     0.5786324696325503,
+    0.326040247765297220,  0.287235637987091563,  0.238080025892859704,
-     0.4006012210123992,     0.23293327870303457,    0.08757875030779196,
+    0.182990955139333916,  0.126689053778116234,  0.073664520037517042,
-    -0.026921412469634916,  -0.10610329539459686,   -0.14969512896336504,
+    0.027696543159614194,  -0.008513823955725943, -0.033554880492651755,
-    -0.16119995609538576,   -0.14703962203941534,   -0.11540977897637611,
+    -0.047340680079891187, -0.050979050575999614, -0.046500883189991064,
-    -0.07502635967975885,   -0.03394615682795165,    0.0013810216516704976,
+    -0.036498030780605324, -0.023726883538258272, -0.010735380379191660,
-     0.02671818654865632,    0.04025481153629372,    0.04244131815783876,
+    0.000436744366018287,  0.008449554307303753,  0.012730475385624438,
-     0.035513467692208076,   0.022816244158307273,   0.008056525910253532,
+    0.013421952197060707,  0.011231038205363532,  0.007215575568844704,
-    -0.0053887880354343935, -0.015005271935951746,  -0.01944761739590459,
+    0.002547854551539951,  -0.001704189656473565, -0.004745376707651645,
-    -0.018598682349642525,  -0.013403099825723372,  -0.0055333532968188165,
+    -0.006150256456781309, -0.005881783042101693, -0.004238694106631223,
-     0.003031522725559901,   0.01042830577908502,    0.015256245142156299,
+    -0.001749908029791816, 0.000958710871218619,  0.003297923526848786,
-     0.01679337935001369,    0.01505751553351295,    0.01071805138282269,
+    0.004824746306020221,  0.005310860846138910,  0.004761898604225673,
-     0.004891777252042491,  -0.001125978562075172,  -0.006136551625729697,
+    0.003389554791179751,  0.001547011339077758,  -0.000356087678023658,
-    -0.009265784007800534
+    -0.001940667871554463, -0.002930279157647190, -0.003195702904062073,
 };
 
 Fir< std::tuple_size< decltype(rrc_taps) >::value > rrc(rrc_taps);

openrtx/src/protocols/M17/M17Demodulator.cpp

@@ -84,7 +84,7 @@ void M17Demodulator::stopBasebandSampling()
 
 void M17Demodulator::resetCorrelationStats() {
     conv_ema = 0.0f;
-    conv_emvar = 10000000000.0f;
+    conv_emvar = 1000000000.0f;
 }
 
 /**

scripts/plot_m17_demod_csv.py

@@ -4,7 +4,7 @@ import pandas as pd
 from matplotlib import pyplot as plt
 
 plt.rcParams["figure.autolayout"] = True
-df = pd.read_csv("./build_linux/M17_clock_recovery_output_1.csv")
+df = pd.read_csv("./build_linux/M17_demodulator_output_1.csv")
 print("Contents in csv file:\n", df)
 #plt.plot(df.index, df.Input)
 #plt.plot(df.index, df.RRCSignal)

tests/unit/M17_demodulator.cpp

@@ -75,7 +75,7 @@ int main()
     for(size_t i = 0; i < baseband_samples; i++)
     {
         float elem = static_cast< float >(baseband_buffer[i]);
-        filtered_buffer[i] = static_cast< int16_t >(M17::rrc(0.10 * elem));
+        filtered_buffer[i] = static_cast< int16_t >(M17::rrc(elem));
     }
     fwrite(filtered_buffer, baseband_samples, 2, baseband_out);
     fclose(baseband_out);
@@ -89,7 +89,7 @@ int main()
     m17Demodulator.baseband = baseband;
     baseband.data = filtered_buffer;
 
-    FILE *output_csv_1 = fopen("M17_clock_recovery_output_1.csv", "w");
+    FILE *output_csv_1 = fopen("M17_demodulator_output_1.csv", "w");
     fprintf(output_csv_1, "Input,RRCSignal,LSFConvolution,FrameConvolution,Stddev\n");
     // Test convolution
     m17Demodulator.resetCorrelationStats();
@@ -139,7 +139,7 @@ int main()
     } while (syncword.index != -1);
     fclose(syncword_ref);
 
-    FILE *output_csv_2 = fopen("M17_clock_recovery_output_2.csv", "w");
+    FILE *output_csv_2 = fopen("M17_demodulator_output_2.csv", "w");
     fprintf(output_csv_2, "RRCSignal,SyncDetect,QntMax,QntMin,Symbol\n");
     uint32_t detect = 0, symbol = 0;
     offset = 0;

tests/unit/assets/M17_test_baseband_syncwords.txt

@@ -1,500 +1,2 @@
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+1957
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 -1