mirror of
https://github.com/aicodix/modem.git
synced 2026-04-27 22:35:41 +00:00
added support for various operation modes:
mode 2: 8PSK, 2700 Hz bandwidth and about 10 seconds long mode 3: 8PSK, 2500 Hz bandwidth and about 11 seconds long mode 4: QPSK, 2500 Hz bandwidth and about 16 seconds long mode 5: QPSK, 2250 Hz bandwidth and about 18 seconds long
This commit is contained in:
Ahmet Inan
parent
fa1cc128be
commit
2645f96056
2 changed files with 169 additions and 46 deletions
114
decode.cc
114
decode.cc
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@ -152,19 +152,21 @@ void base37_decoder(char *str, long long int val, int len)
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str[i] = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[val%37];
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}
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template <typename value, typename cmplx, int rate, int cols_min>
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template <typename value, typename cmplx, int rate>
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struct Decoder
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{
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typedef DSP::Const<value> Const;
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typedef PhaseShiftKeying<8, cmplx, int8_t> Mod;
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static const int symbol_len = (1280 * rate) / 8000;
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static const int filter_len = (((21 * rate) / 8000) & ~3) | 1;
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static const int guard_len = symbol_len / 8;
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static const int ldpc_bits = 64800;
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static const int bch_bits = ldpc_bits - 21600;
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static const int data_bits = bch_bits - 12 * 16;
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static const int cons_cnt = ldpc_bits / Mod::BITS;
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static const int rows_max = cons_cnt / cols_min;
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static const int mod_min = 2;
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static const int mod_max = 3;
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static const int cons_max = ldpc_bits / mod_min;
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static const int cols_min = 360;
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static const int rows_max = cons_max / cols_min;
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static const int mls0_len = 127;
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static const int mls0_off = - mls0_len + 1;
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static const int mls0_poly = 0b10001001;
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@ -192,11 +194,14 @@ struct Decoder
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int8_t genmat[255*71];
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int8_t code[ldpc_bits], bint[ldpc_bits];
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uint16_t erasures[24];
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cmplx head[symbol_len], tail[symbol_len], cons[cons_cnt];
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cmplx head[symbol_len], tail[symbol_len], cons[cons_max];
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cmplx fdom[symbol_len], tdom[buffer_len], resam[buffer_len];
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value phase[symbol_len/2];
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value cfo_rad, sfo_rad;
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int symbol_pos;
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int oper_mode;
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int mod_bits;
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int cons_cnt;
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static int bin(int carrier)
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{
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@ -253,16 +258,54 @@ struct Decoder
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void deinterleave()
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{
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for (int i = 0; i < cons_cnt; ++i)
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for (int k = 0; k < Mod::BITS; ++k)
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code[cons_cnt*k+i] = bint[Mod::BITS*i+k];
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for (int k = 0; k < mod_bits; ++k)
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code[cons_cnt*k+i] = bint[mod_bits*i+k];
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}
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void interleave()
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{
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for (int i = 0; i < cons_cnt; ++i)
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for (int k = 0; k < Mod::BITS; ++k)
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bint[Mod::BITS*i+k] = code[cons_cnt*k+i];
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for (int k = 0; k < mod_bits; ++k)
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bint[mod_bits*i+k] = code[cons_cnt*k+i];
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}
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Decoder(uint8_t *out, DSP::ReadPCM<value> *pcm, int skip_count, int code_cols) :
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cmplx mod_map(int8_t *b)
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{
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switch (oper_mode) {
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case 2:
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case 3:
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return PhaseShiftKeying<8, cmplx, int8_t>::map(b);
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case 4:
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case 5:
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return PhaseShiftKeying<4, cmplx, int8_t>::map(b);
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}
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return 0;
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}
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void mod_hard(int8_t *b, cmplx c)
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{
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switch (oper_mode) {
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case 2:
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case 3:
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PhaseShiftKeying<8, cmplx, int8_t>::hard(b, c);
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break;
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case 4:
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case 5:
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PhaseShiftKeying<4, cmplx, int8_t>::hard(b, c);
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break;
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}
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}
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void mod_soft(int8_t *b, cmplx c, value precision)
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{
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switch (oper_mode) {
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case 2:
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case 3:
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PhaseShiftKeying<8, cmplx, int8_t>::soft(b, c, precision);
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break;
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case 4:
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case 5:
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PhaseShiftKeying<4, cmplx, int8_t>::soft(b, c, precision);
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break;
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}
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}
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Decoder(uint8_t *out, DSP::ReadPCM<value> *pcm, int skip_count) :
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pcm(pcm), resample(rate, (rate * 19) / 40, 2), correlator(mls0_seq()), crc0(0xA8F4)
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{
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CODE::BoseChaudhuriHocquenghemGenerator<255, 71>::matrix(genmat, true, {
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@ -323,10 +366,31 @@ struct Decoder
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std::cerr << "header CRC error." << std::endl;
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return;
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}
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if ((md&255) != 2) {
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std::cerr << "operation mode unsupported." << std::endl;
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oper_mode = md & 255;
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int code_cols;
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switch (oper_mode) {
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case 2:
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code_cols = 432;
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mod_bits = 3;
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break;
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case 3:
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code_cols = 400;
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mod_bits = 3;
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break;
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case 4:
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code_cols = 400;
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mod_bits = 2;
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break;
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case 5:
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code_cols = 360;
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mod_bits = 2;
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break;
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default:
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std::cerr << "operation mode " << oper_mode << " unsupported." << std::endl;
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return;
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}
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cons_cnt = ldpc_bits / mod_bits;
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std::cerr << "oper mode: " << oper_mode << std::endl;
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if ((md>>8) == 0 || (md>>8) >= 129961739795077L) {
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std::cerr << "call sign unsupported." << std::endl;
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return;
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@ -374,9 +438,9 @@ struct Decoder
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if (1) {
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value sp = 0, np = 0;
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for (int i = 0; i < cons_cnt; ++i) {
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int8_t tmp[Mod::BITS];
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Mod::hard(tmp, cons[i]);
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cmplx hard = Mod::map(tmp);
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int8_t tmp[mod_max];
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mod_hard(tmp, cons[i]);
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cmplx hard = mod_map(tmp);
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cmplx error = cons[i] - hard;
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sp += norm(hard);
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np += norm(error);
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@ -389,7 +453,7 @@ struct Decoder
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precision = 1 / (sigma * sigma);
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}
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for (int i = 0; i < cons_cnt; ++i)
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Mod::soft(bint+Mod::BITS*i, cons[i], precision);
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mod_soft(bint+mod_bits*i, cons[i], precision);
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deinterleave();
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int count = ldpcdec(code, code + bch_bits);
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if (count < 0)
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@ -398,10 +462,10 @@ struct Decoder
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interleave();
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value sp = 0, np = 0;
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for (int i = 0; i < cons_cnt; ++i) {
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int8_t tmp[Mod::BITS];
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for (int k = 0; k < Mod::BITS; ++k)
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tmp[k] = nrz(bint[Mod::BITS*i+k] < 0);
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cmplx hard = Mod::map(tmp);
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int8_t tmp[mod_max];
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for (int k = 0; k < mod_bits; ++k)
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tmp[k] = nrz(bint[mod_bits*i+k] < 0);
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cmplx hard = mod_map(tmp);
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cmplx error = cons[i] - hard;
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sp += norm(hard);
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np += norm(error);
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@ -462,21 +526,21 @@ int main(int argc, char **argv)
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if (argc > 3)
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skip_count = std::atoi(argv[3]);
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const int code_len = 64800 / 8, code_cols = 432, cols_min = 360;
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const int code_len = 64800 / 8;
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uint8_t *output_data = new uint8_t[code_len];
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switch (input_file.rate()) {
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case 8000:
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delete new Decoder<value, cmplx, 8000, cols_min>(output_data, &input_file, skip_count, code_cols);
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delete new Decoder<value, cmplx, 8000>(output_data, &input_file, skip_count);
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break;
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case 16000:
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delete new Decoder<value, cmplx, 16000, cols_min>(output_data, &input_file, skip_count, code_cols);
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delete new Decoder<value, cmplx, 16000>(output_data, &input_file, skip_count);
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break;
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case 44100:
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delete new Decoder<value, cmplx, 44100, cols_min>(output_data, &input_file, skip_count, code_cols);
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delete new Decoder<value, cmplx, 44100>(output_data, &input_file, skip_count);
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break;
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case 48000:
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delete new Decoder<value, cmplx, 48000, cols_min>(output_data, &input_file, skip_count, code_cols);
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delete new Decoder<value, cmplx, 48000>(output_data, &input_file, skip_count);
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break;
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default:
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std::cerr << "Unsupported sample rate." << std::endl;
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