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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include/modulation/PSKModulator.h
+14 -4
View File
@@ -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;
include/utils/costasloop.h
+10 -4
View File
@@ -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);