RecklessAndFeckless/MIL-STD-188-110C
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I'm a little lost again

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RecklessAndFeckless 2024-10-14 17:43:33 -04:00
parent 010e479f89
commit cfbbacdd0f
4 changed files with 72 additions and 28 deletions
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18
include/modulation/PSKModulator.h
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@ -22,8 +22,9 @@ static constexpr double SCALE_FACTOR = 32767.0;
class PSKModulator {
public:
PSKModulator(const double _sample_rate, const bool _is_frequency_hopping, const size_t _num_taps)
: sample_rate(validateSampleRate(_sample_rate)), gain(1.0/sqrt(2.0)), is_frequency_hopping(_is_frequency_hopping), samples_per_symbol(static_cast<size_t>(sample_rate / SYMBOL_RATE)), phase_detector(symbolMap), srrc_filter(48, _sample_rate, SYMBOL_RATE, ROLLOFF_FACTOR) {
: sample_rate(validateSampleRate(_sample_rate)), gain(1.0/sqrt(2.0)), is_frequency_hopping(_is_frequency_hopping), samples_per_symbol(static_cast<size_t>(sample_rate / SYMBOL_RATE)), srrc_filter(48, _sample_rate, SYMBOL_RATE, ROLLOFF_FACTOR) {
initializeSymbolMap();
phase_detector = PhaseDetector(symbolMap);
}
std::vector<int16_t> modulate(const std::vector<uint8_t>& symbols) {
@ -78,7 +79,7 @@ public:
std::vector<uint8_t> demodulate(const std::vector<int16_t> passband_signal) {
// Carrier recovery. initialize the Costas loop.
CostasLoop costas_loop(sample_rate, symbolMap);
CostasLoop costas_loop(CARRIER_FREQ, sample_rate, symbolMap, 5.0);
// Convert passband signal to doubles.
std::vector<double> normalized_passband(passband_signal.size());
@ -91,8 +92,17 @@ public:
// Phase detection and symbol formation
std::vector<uint8_t> baseband_symbols;
for (size_t i = 0; i < baseband_IQ.size(); i++) {
baseband_symbols.emplace_back(phase_detector.getSymbol(baseband_IQ[i]));
size_t samples_per_symbol = sample_rate / SYMBOL_RATE;
for (size_t i = 0; i < baseband_IQ.size(); i += samples_per_symbol) {
std::complex<double> symbol_avg(0.0, 0.0);
for (size_t j = 0; j < samples_per_symbol; ++j) {
symbol_avg += baseband_IQ[i + j];
}
symbol_avg /= static_cast<double>(samples_per_symbol);
// Detect symbol from averaged signal
baseband_symbols.emplace_back(phase_detector.getSymbol(symbol_avg));
}
return baseband_symbols;

14
include/utils/costasloop.h
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@ -7,6 +7,7 @@
class PhaseDetector {
public:
PhaseDetector() {}
PhaseDetector(const std::vector<std::complex<double>>& _symbolMap) : symbolMap(_symbolMap) {}
uint8_t getSymbol(const std::complex<double>& input) {
@ -38,8 +39,8 @@ private:
class CostasLoop {
public:
CostasLoop(const double _sample_rate, const std::vector<std::complex<double>>& _symbolMap)
: sample_rate(_sample_rate), k_factor(-5 / _sample_rate),
CostasLoop(const double _carrier_freq, const double _sample_rate, const std::vector<std::complex<double>>& _symbolMap, const double _vco_gain)
: carrier_freq(_carrier_freq), sample_rate(_sample_rate), vco_gain(_vco_gain), k_factor(-1 / (_sample_rate * _vco_gain)),
prev_in_iir(0), prev_out_iir(0), prev_in_vco(0), feedback(1.0, 0.0),
error_total(0), out_iir_total(0), in_vco_total(0),
srrc_filter(SRRCFilter(48, _sample_rate, 2400, 0.35)) {}
@ -80,15 +81,19 @@ public:
prev_in_vco = in_vco;
// Generate feedback signal for next iteration
double feedback_real = std::cos(k_factor * in_vco);
double feedback_imag = -std::sin(k_factor * in_vco);
double feedback_real = std::cos(current_phase);
double feedback_imag = -std::sin(current_phase);
feedback = std::complex<double>(feedback_real, feedback_imag);
current_phase += 2 * M_PI * carrier_freq / sample_rate + k_factor * in_vco;
if (current_phase > 2 * M_PI) current_phase -= 2 * M_PI;
}
return output_signal;
}
private:
double carrier_freq;
double sample_rate;
double k_factor;
double prev_in_iir;
@ -99,6 +104,7 @@ private:
double out_iir_total;
double in_vco_total;
SRRCFilter srrc_filter;
double vco_gain;
std::complex<double> limiter(const std::complex<double>& sample) const {
double limited_I = std::clamp(sample.real(), -1.0, 1.0);

42
main.cpp
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@ -6,6 +6,7 @@
#include <vector>
#include "ModemController.h"
#include "PSKModulator.h"
int main() {
// Sample test data
@ -16,37 +17,40 @@ int main() {
BitStream input_data(sample_data, sample_data.size() * 8);
// Configuration for modem
size_t baud_rate = 300;
size_t baud_rate = 150;
bool is_voice = false; // False indicates data mode
bool is_frequency_hopping = false; // Fixed frequency operation
size_t interleave_setting = 1; // Short interleave
// Create ModemController instance
ModemController modem(baud_rate, is_voice, is_frequency_hopping, interleave_setting, input_data);
PSKModulator modulator(48000, is_frequency_hopping, 48);
const char* file_name = "modulated_signal_600bps_shortinterleave.wav";
const char* file_name = "modulated_signal_75bps_shortinterleave.wav";
// Perform transmit operation to generate modulated signal
std::vector<int16_t> modulated_signal = modem.transmit();
// Output modulated signal to a WAV file using libsndfile
SF_INFO sfinfo;
sfinfo.channels = 1;
sfinfo.samplerate = 48000;
sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
std::vector<uint8_t> demodulated_symbols = modulator.demodulate(modulated_signal);
SNDFILE* sndfile = sf_open(file_name, SFM_WRITE, &sfinfo);
if (sndfile == nullptr) {
std::cerr << "Unable to open WAV file for writing modulated signal: " << sf_strerror(sndfile) << "\n";
return 1;
}
sf_write_short(sndfile, modulated_signal.data(), modulated_signal.size());
sf_close(sndfile);
std::cout << "Modulated signal written to " << file_name << '\n';
// Success message
std::cout << "Modem test completed successfully.\n";
//// Output modulated signal to a WAV file using libsndfile
//SF_INFO sfinfo;
//sfinfo.channels = 1;
//sfinfo.samplerate = 48000;
//sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
//
//SNDFILE* sndfile = sf_open(file_name, SFM_WRITE, &sfinfo);
//if (sndfile == nullptr) {
// std::cerr << "Unable to open WAV file for writing modulated signal: " << sf_strerror(sndfile) << "\n";
// return 1;
//}
//
//sf_write_short(sndfile, modulated_signal.data(), modulated_signal.size());
//sf_close(sndfile);
//std::cout << "Modulated signal written to " << file_name << '\n';
//
//// Success message
//std::cout << "Modem test completed successfully.\n";
return 0;
}

26
tests/PSKModulatorTests.cpp
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@ -26,14 +26,38 @@ TEST_F(PSKModulatorTest, ModulationOutputLength) {
TEST_F(PSKModulatorTest, DemodulationOutput) {
auto passband_signal = modulator.modulate(symbols);
// Debug: Print modulated passband signal
std::cout << "Modulated Passband Signal: ";
for (const auto& sample : passband_signal) {
std::cout << sample << " ";
}
std::cout << std::endl;
auto decoded_symbols = modulator.demodulate(passband_signal);
// Debug: Print decoded symbols
std::cout << "Decoded Symbols: ";
for (const auto& symbol : decoded_symbols) {
std::cout << (int)symbol << " ";
}
std::cout << std::endl;
// Debug: Print expected symbols
std::cout << "Expected Symbols: ";
for (const auto& symbol : symbols) {
std::cout << (int)symbol << " ";
}
std::cout << std::endl;
ASSERT_EQ(symbols.size(), decoded_symbols.size());
for (size_t i = 0; i < symbols.size(); i++) {
EXPECT_EQ(symbols[i], decoded_symbols[i]);
EXPECT_EQ(symbols[i], decoded_symbols[i]) << " at index " << i;
}
}
TEST_F(PSKModulatorTest, InvalidSymbolInput) {
std::vector<uint8_t> invalid_symbols = {0, 8, 9};