I'm a little lost again
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@ -22,8 +22,9 @@ static constexpr double SCALE_FACTOR = 32767.0;
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class PSKModulator {
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public:
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PSKModulator(const double _sample_rate, const bool _is_frequency_hopping, const size_t _num_taps)
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: 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) {
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: 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) {
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initializeSymbolMap();
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phase_detector = PhaseDetector(symbolMap);
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}
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std::vector<int16_t> modulate(const std::vector<uint8_t>& symbols) {
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@ -78,7 +79,7 @@ public:
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std::vector<uint8_t> demodulate(const std::vector<int16_t> passband_signal) {
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// Carrier recovery. initialize the Costas loop.
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CostasLoop costas_loop(sample_rate, symbolMap);
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CostasLoop costas_loop(CARRIER_FREQ, sample_rate, symbolMap, 5.0);
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// Convert passband signal to doubles.
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std::vector<double> normalized_passband(passband_signal.size());
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@ -91,8 +92,17 @@ public:
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// Phase detection and symbol formation
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std::vector<uint8_t> baseband_symbols;
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for (size_t i = 0; i < baseband_IQ.size(); i++) {
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baseband_symbols.emplace_back(phase_detector.getSymbol(baseband_IQ[i]));
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size_t samples_per_symbol = sample_rate / SYMBOL_RATE;
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for (size_t i = 0; i < baseband_IQ.size(); i += samples_per_symbol) {
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std::complex<double> symbol_avg(0.0, 0.0);
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for (size_t j = 0; j < samples_per_symbol; ++j) {
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symbol_avg += baseband_IQ[i + j];
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}
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symbol_avg /= static_cast<double>(samples_per_symbol);
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// Detect symbol from averaged signal
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baseband_symbols.emplace_back(phase_detector.getSymbol(symbol_avg));
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}
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return baseband_symbols;
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@ -7,6 +7,7 @@
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class PhaseDetector {
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public:
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PhaseDetector() {}
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PhaseDetector(const std::vector<std::complex<double>>& _symbolMap) : symbolMap(_symbolMap) {}
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uint8_t getSymbol(const std::complex<double>& input) {
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@ -38,8 +39,8 @@ private:
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class CostasLoop {
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public:
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CostasLoop(const double _sample_rate, const std::vector<std::complex<double>>& _symbolMap)
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: sample_rate(_sample_rate), k_factor(-5 / _sample_rate),
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CostasLoop(const double _carrier_freq, const double _sample_rate, const std::vector<std::complex<double>>& _symbolMap, const double _vco_gain)
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: carrier_freq(_carrier_freq), sample_rate(_sample_rate), vco_gain(_vco_gain), k_factor(-1 / (_sample_rate * _vco_gain)),
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prev_in_iir(0), prev_out_iir(0), prev_in_vco(0), feedback(1.0, 0.0),
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error_total(0), out_iir_total(0), in_vco_total(0),
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srrc_filter(SRRCFilter(48, _sample_rate, 2400, 0.35)) {}
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@ -80,15 +81,19 @@ public:
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prev_in_vco = in_vco;
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// Generate feedback signal for next iteration
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double feedback_real = std::cos(k_factor * in_vco);
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double feedback_imag = -std::sin(k_factor * in_vco);
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double feedback_real = std::cos(current_phase);
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double feedback_imag = -std::sin(current_phase);
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feedback = std::complex<double>(feedback_real, feedback_imag);
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current_phase += 2 * M_PI * carrier_freq / sample_rate + k_factor * in_vco;
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if (current_phase > 2 * M_PI) current_phase -= 2 * M_PI;
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}
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return output_signal;
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}
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private:
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double carrier_freq;
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double sample_rate;
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double k_factor;
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double prev_in_iir;
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@ -99,6 +104,7 @@ private:
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double out_iir_total;
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double in_vco_total;
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SRRCFilter srrc_filter;
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double vco_gain;
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std::complex<double> limiter(const std::complex<double>& sample) const {
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double limited_I = std::clamp(sample.real(), -1.0, 1.0);
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42
main.cpp
42
main.cpp
@ -6,6 +6,7 @@
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#include <vector>
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#include "ModemController.h"
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#include "PSKModulator.h"
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int main() {
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// Sample test data
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@ -16,37 +17,40 @@ int main() {
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BitStream input_data(sample_data, sample_data.size() * 8);
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// Configuration for modem
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size_t baud_rate = 300;
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size_t baud_rate = 150;
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bool is_voice = false; // False indicates data mode
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bool is_frequency_hopping = false; // Fixed frequency operation
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size_t interleave_setting = 1; // Short interleave
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// Create ModemController instance
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ModemController modem(baud_rate, is_voice, is_frequency_hopping, interleave_setting, input_data);
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PSKModulator modulator(48000, is_frequency_hopping, 48);
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const char* file_name = "modulated_signal_600bps_shortinterleave.wav";
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const char* file_name = "modulated_signal_75bps_shortinterleave.wav";
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// Perform transmit operation to generate modulated signal
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std::vector<int16_t> modulated_signal = modem.transmit();
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// Output modulated signal to a WAV file using libsndfile
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SF_INFO sfinfo;
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sfinfo.channels = 1;
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sfinfo.samplerate = 48000;
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sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
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std::vector<uint8_t> demodulated_symbols = modulator.demodulate(modulated_signal);
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SNDFILE* sndfile = sf_open(file_name, SFM_WRITE, &sfinfo);
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if (sndfile == nullptr) {
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std::cerr << "Unable to open WAV file for writing modulated signal: " << sf_strerror(sndfile) << "\n";
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return 1;
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}
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sf_write_short(sndfile, modulated_signal.data(), modulated_signal.size());
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sf_close(sndfile);
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std::cout << "Modulated signal written to " << file_name << '\n';
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// Success message
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std::cout << "Modem test completed successfully.\n";
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//// Output modulated signal to a WAV file using libsndfile
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//SF_INFO sfinfo;
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//sfinfo.channels = 1;
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//sfinfo.samplerate = 48000;
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//sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
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//
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//SNDFILE* sndfile = sf_open(file_name, SFM_WRITE, &sfinfo);
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//if (sndfile == nullptr) {
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// std::cerr << "Unable to open WAV file for writing modulated signal: " << sf_strerror(sndfile) << "\n";
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// return 1;
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//}
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//
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//sf_write_short(sndfile, modulated_signal.data(), modulated_signal.size());
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//sf_close(sndfile);
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//std::cout << "Modulated signal written to " << file_name << '\n';
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//
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//// Success message
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//std::cout << "Modem test completed successfully.\n";
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return 0;
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}
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@ -26,14 +26,38 @@ TEST_F(PSKModulatorTest, ModulationOutputLength) {
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TEST_F(PSKModulatorTest, DemodulationOutput) {
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auto passband_signal = modulator.modulate(symbols);
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// Debug: Print modulated passband signal
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std::cout << "Modulated Passband Signal: ";
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for (const auto& sample : passband_signal) {
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std::cout << sample << " ";
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}
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std::cout << std::endl;
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auto decoded_symbols = modulator.demodulate(passband_signal);
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// Debug: Print decoded symbols
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std::cout << "Decoded Symbols: ";
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for (const auto& symbol : decoded_symbols) {
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std::cout << (int)symbol << " ";
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}
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std::cout << std::endl;
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// Debug: Print expected symbols
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std::cout << "Expected Symbols: ";
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for (const auto& symbol : symbols) {
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std::cout << (int)symbol << " ";
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}
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std::cout << std::endl;
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ASSERT_EQ(symbols.size(), decoded_symbols.size());
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for (size_t i = 0; i < symbols.size(); i++) {
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EXPECT_EQ(symbols[i], decoded_symbols[i]);
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EXPECT_EQ(symbols[i], decoded_symbols[i]) << " at index " << i;
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}
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}
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TEST_F(PSKModulatorTest, InvalidSymbolInput) {
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std::vector<uint8_t> invalid_symbols = {0, 8, 9};
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