104 lines
2.9 KiB
C++
104 lines
2.9 KiB
C++
#include <cstdlib>
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#include <cstring>
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#include <cstdio>
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#include <cmath>
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#include "common/wave.h"
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//#include "ft8/v1/pack.h"
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//#include "ft8/v1/encode.h"
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#include "ft8/pack.h"
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#include "ft8/encode.h"
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#include "ft8/constants.h"
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// Convert a sequence of symbols (tones) into a sinewave of continuous phase (FSK).
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// Symbol 0 gets encoded as a sine of frequency f0, the others are spaced in increasing
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// fashion.
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void synth_fsk(const uint8_t *symbols, int num_symbols, float f0, float spacing,
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float symbol_rate, float signal_rate, float *signal) {
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float phase = 0;
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float dt = 1/signal_rate;
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float dt_sym = 1/symbol_rate;
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float t = 0;
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int j = 0;
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int i = 0;
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while (j < num_symbols) {
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float f = f0 + symbols[j] * spacing;
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phase += 2 * M_PI * f / signal_rate;
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signal[i] = sin(phase);
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t += dt;
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if (t >= dt_sym) {
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// Move to the next symbol
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t -= dt_sym;
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++j;
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}
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++i;
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}
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}
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void usage() {
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printf("Generate a 15-second WAV file encoding a given message.\n");
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printf("Usage:\n");
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printf("\n");
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printf("gen_ft8 MESSAGE WAV_FILE [FREQUENCY]\n");
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printf("\n");
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printf("(Note that you might have to enclose your message in quote marks if it contains spaces)\n");
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}
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int main(int argc, char **argv) {
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// Expect two command-line arguments
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if (argc < 3) {
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usage();
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return -1;
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}
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const char *message = argv[1];
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const char *wav_path = argv[2];
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int frequency = 1000;
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if (argc > 3) {
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frequency = atoi(argv[3]);
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}
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// First, pack the text data into binary message
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uint8_t packed[ft8::K_BYTES];
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//int rc = packmsg(message, packed);
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int rc = ft8::pack77(message, packed);
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if (rc < 0) {
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printf("Cannot parse message!\n");
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printf("RC = %d\n", rc);
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return -2;
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}
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printf("Packed data: ");
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for (int j = 0; j < 10; ++j) {
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printf("%02x ", packed[j]);
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}
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printf("\n");
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// Second, encode the binary message as a sequence of FSK tones
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uint8_t tones[ft8::NN]; // FT8_NN = 79, lack of better name at the moment
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//genft8(packed, 0, tones);
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ft8::genft8(packed, tones);
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printf("FSK tones: ");
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for (int j = 0; j < ft8::NN; ++j) {
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printf("%d", tones[j]);
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}
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printf("\n");
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// Third, convert the FSK tones into an audio signal
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const int sample_rate = 12000;
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const float symbol_rate = 6.25f;
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const int num_samples = (int)(0.5f + ft8::NN / symbol_rate * sample_rate);
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const int num_silence = (15 * sample_rate - num_samples) / 2;
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float signal[num_silence + num_samples + num_silence];
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for (int i = 0; i < num_silence + num_samples + num_silence; i++) {
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signal[i] = 0;
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}
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synth_fsk(tones, ft8::NN, frequency, symbol_rate, symbol_rate, sample_rate, signal + num_silence);
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save_wav(signal, num_silence + num_samples + num_silence, sample_rate, wav_path);
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return 0;
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}
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