From 4b99f82aac55ef0b1ed2c00a732abca303827416 Mon Sep 17 00:00:00 2001 From: Ahmet Inan Date: Mon, 30 Jun 2025 12:36:35 +0200 Subject: [PATCH] use the first 32 comb pilots to signal the mode --- decode.cc | 169 +++++++++++++++++++----------------------------------- encode.cc | 145 +++++++++++++--------------------------------- 2 files changed, 99 insertions(+), 215 deletions(-) diff --git a/decode.cc b/decode.cc index 456d9f0..d2d9b2c 100644 --- a/decode.cc +++ b/decode.cc @@ -24,17 +24,12 @@ namespace DSP { using std::abs; using std::min; using std::cos; using std::sin; #include "fft.hh" #include "mls.hh" #include "crc.hh" -#include "osd.hh" #include "psk.hh" #include "qam.hh" #include "polar_tables.hh" #include "polar_list_decoder.hh" - -void base37_decoder(char *str, long long int val, int len) -{ - for (int i = len-1; i >= 0; --i, val /= 37) - str[i] = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[val%37]; -} +#include "hadamard_encoder.hh" +#include "hadamard_decoder.hh" template struct Decoder @@ -61,8 +56,6 @@ struct Decoder static const int mls0_poly = 0b1100110001; static const int mls0_seed = 214; static const int mls0_off = - mls0_len / 2; - static const int mls1_len = 255; - static const int mls1_off = - mls1_len / 2; static const int mls1_poly = 0b100101011; static const int buffer_len = 5 * extended_len; static const int search_pos = extended_len; @@ -73,15 +66,15 @@ struct Decoder DSP::BipBuffer input_hist; DSP::TheilSenEstimator tse; SchmidlCox correlator; - CODE::CRC crc0; CODE::CRC crc1; - CODE::OrderedStatisticsDecoder<255, 71, 4> osddec; + CODE::HadamardEncoder<6> hadamardenc; + CODE::HadamardDecoder<6> hadamarddec; CODE::PolarListDecoder polardec; uint8_t output_data[data_max]; - int8_t genmat[255*71]; mesg_type mesg[bits_max]; code_type code[bits_max], perm[bits_max]; - cmplx cons[cons_max], prev[cols_max]; + int8_t mode[32]; + cmplx cons[cons_max], chan[cols_max]; cmplx fdom[symbol_len], tdom[symbol_len]; value index[cols_max], phase[cols_max]; value cfo_rad, sfo_rad; @@ -196,20 +189,18 @@ struct Decoder return input_hist(tmp); } Decoder(DSP::ReadPCM *pcm, const char *const *output_names, int output_count) : - pcm(pcm), correlator(mls0_seq()), crc0(0xA8F4), crc1(0x8F6E37A0) + pcm(pcm), correlator(mls0_seq()), crc1(0x8F6E37A0) { - CODE::BoseChaudhuriHocquenghemGenerator<255, 71>::matrix(genmat, true, { - 0b100011101, 0b101110111, 0b111110011, 0b101101001, - 0b110111101, 0b111100111, 0b100101011, 0b111010111, - 0b000010011, 0b101100101, 0b110001011, 0b101100011, - 0b100011011, 0b100111111, 0b110001101, 0b100101101, - 0b101011111, 0b111111001, 0b111000011, 0b100111001, - 0b110101001, 0b000011111, 0b110000111, 0b110110001}); - blockdc.samples(filter_len); DSP::Phasor osc; const cmplx *buf; int output_index = 0; + int comb_cols = 32; + int code_cols = 256; + int comb_dist = 9; + int comb_off = 4; + int cons_cols = code_cols + comb_cols; + int code_off = - cons_cols / 2; while (output_index < output_count) { do { if (!pcm->good()) @@ -223,108 +214,87 @@ struct Decoder std::cerr << "coarse cfo: " << cfo_rad * (rate / Const::TwoPi()) << " Hz " << std::endl; osc.omega(-cfo_rad); + for (int i = 0; i < symbol_len; ++i) + tdom[i] = buf[i+symbol_pos+symbol_len] * osc(); + for (int i = 0; i < guard_len; ++i) + osc(); + fwd(fdom, tdom); + CODE::MLS seq0(mls0_poly, mls0_seed); + for (int i = 0; i < mls0_len; ++i) + fdom[bin(i+mls0_off)] *= nrz(seq0()); + for (int i = 0; i < cons_cols; ++i) + chan[i] = fdom[bin(i+code_off)]; for (int i = 0; i < symbol_len; ++i) tdom[i] = buf[i+symbol_pos+symbol_len+extended_len] * osc(); + for (int i = 0; i < guard_len; ++i) + osc(); fwd(fdom, tdom); CODE::MLS seq1(mls1_poly); - for (int i = 0; i < mls1_len; ++i) - fdom[bin(i+mls1_off)] *= nrz(seq1()); - int8_t soft[mls1_len]; - uint8_t data[(mls1_len+7)/8]; - for (int i = 0; i < mls1_len; ++i) - soft[i] = std::min(std::max( - std::nearbyint(127 * demod_or_erase( - fdom[bin(i+mls1_off)], fdom[bin(i-1+mls1_off)]).real()), - -127), 127); - bool unique = osddec(data, soft, genmat); - if (!unique) { - std::cerr << "OSD error." << std::endl; - continue; - } - uint64_t md = 0; - for (int i = 0; i < 55; ++i) - md |= (uint64_t)CODE::get_be_bit(data, i) << i; - uint16_t cs = 0; - for (int i = 0; i < 16; ++i) - cs |= (uint16_t)CODE::get_be_bit(data, i+55) << i; - crc0.reset(); - if (crc0(md<<9) != cs) { - std::cerr << "header CRC error." << std::endl; - continue; - } - oper_mode = md & 255; - if (oper_mode && (oper_mode < 23 || oper_mode > 30)) { + auto clamp = [](int v){ return v < -127 ? -127 : v > 127 ? 127 : v; }; + for (int i = 0; i < comb_cols; ++i) + mode[i] = clamp(std::nearbyint(127 * demod_or_erase(fdom[bin(i*comb_dist+comb_off+code_off)], chan[i]).real() * nrz(seq1()))); + oper_mode = hadamarddec(mode); + if (oper_mode < 0 || oper_mode > 8) { std::cerr << "operation mode " << oper_mode << " unsupported." << std::endl; continue; } std::cerr << "oper mode: " << oper_mode << std::endl; - if ((md>>8) == 0 || (md>>8) >= 129961739795077L) { - std::cerr << "call sign unsupported." << std::endl; - continue; - } - char call_sign[10]; - base37_decoder(call_sign, md>>8, 9); - call_sign[9] = 0; - std::cerr << "call sign: " << call_sign << std::endl; if (!oper_mode) continue; + int data_bits = 0; int cons_rows = 0; - int comb_cols = 32; - int code_cols = 256; - int comb_dist = 9; - int comb_off = 4; switch (oper_mode) { - case 23: + case 1: mod_bits = 2; cons_rows = 8; code_order = 12; data_bits = 2048; frozen_bits = frozen_4096_2080; break; - case 24: + case 2: mod_bits = 2; cons_rows = 16; code_order = 13; data_bits = 4096; frozen_bits = frozen_8192_4128; break; - case 25: + case 3: mod_bits = 2; cons_rows = 32; code_order = 14; data_bits = 8192; frozen_bits = frozen_16384_8224; break; - case 26: + case 4: mod_bits = 4; cons_rows = 4; code_order = 12; data_bits = 2048; frozen_bits = frozen_4096_2080; break; - case 27: + case 5: mod_bits = 4; cons_rows = 8; code_order = 13; data_bits = 4096; frozen_bits = frozen_8192_4128; break; - case 28: + case 6: mod_bits = 4; cons_rows = 16; code_order = 14; data_bits = 8192; frozen_bits = frozen_16384_8224; break; - case 29: + case 7: mod_bits = 6; cons_rows = 6; code_order = 13; data_bits = 4096; frozen_bits = frozen_8192_4128; break; - case 30: + case 8: mod_bits = 6; cons_rows = 11; code_order = 14; @@ -335,32 +305,27 @@ struct Decoder return; } int data_bytes = data_bits / 8; - int cons_cols = code_cols + comb_cols; - int code_off = - cons_cols / 2; - for (int i = 0; i < symbol_pos+symbol_len+extended_len; ++i) - correlator(buf = next_sample()); - for (int i = 0; i < symbol_len; ++i) - tdom[i] = buf[i] * osc(); - for (int i = 0; i < guard_len; ++i) - osc(); - fwd(fdom, tdom); - for (int i = 0; i < cons_cols; ++i) - prev[i] = fdom[bin(i+code_off)]; std::cerr << "demod "; - CODE::MLS seq0(mls0_poly); for (int j = 0; j < cons_rows; ++j) { - for (int i = 0; i < extended_len; ++i) - correlator(buf = next_sample()); - for (int i = 0; i < symbol_len; ++i) - tdom[i] = buf[i] * osc(); - for (int i = 0; i < guard_len; ++i) - osc(); - fwd(fdom, tdom); - for (int i = 0; i < cons_cols; ++i) - cons[cons_cols*j+i] = demod_or_erase(fdom[bin(i+code_off)], prev[i]); + if (j) { + for (int i = 0; i < extended_len; ++i) + correlator(buf = next_sample()); + for (int i = 0; i < symbol_len; ++i) + tdom[i] = buf[i] * osc(); + for (int i = 0; i < guard_len; ++i) + osc(); + fwd(fdom, tdom); + } else { + for (int i = 0; i < symbol_pos+symbol_len+extended_len; ++i) + correlator(buf = next_sample()); + seq1.reset(); + hadamardenc(mode, oper_mode); + } for (int i = 0; i < comb_cols; ++i) - cons[cons_cols*j+comb_dist*i+comb_off] *= nrz(seq0()); + fdom[bin(comb_dist*i+comb_off+code_off)] *= nrz(seq1()) * mode[i]; + for (int i = 0; i < cons_cols; ++i) + cons[cons_cols*j+i] = demod_or_erase(fdom[bin(i+code_off)], chan[i]); for (int i = 0; i < comb_cols; ++i) { index[i] = code_off + comb_dist * i + comb_off; phase[i] = arg(cons[cons_cols*j+comb_dist*i+comb_off]); @@ -372,27 +337,9 @@ struct Decoder cons[cons_cols*j+i] *= DSP::polar(1, -tse(i+code_off)); for (int i = 0; i < cons_cols; ++i) if (i % comb_dist == comb_off) - prev[i] = fdom[bin(i+code_off)]; + chan[i] = fdom[bin(i+code_off)]; else - prev[i] *= DSP::polar(1, tse(i+code_off)); - for (int i = 0; i < cons_cols; ++i) { - index[i] = code_off + i; - if (i % comb_dist == comb_off) { - phase[i] = arg(cons[cons_cols*j+i]); - } else { - code_type tmp[mod_max]; - mod_hard(tmp, cons[cons_cols*j+i]); - phase[i] = arg(cons[cons_cols*j+i] * conj(mod_map(tmp))); - } - } - tse.compute(index, phase, cons_cols); - //std::cerr << "Theil-Sen slope = " << tse.slope() << std::endl; - //std::cerr << "Theil-Sen yint = " << tse.yint() << std::endl; - for (int i = 0; i < cons_cols; ++i) - cons[cons_cols*j+i] *= DSP::polar(1, -tse(i+code_off)); - for (int i = 0; i < cons_cols; ++i) - if (i % comb_dist != comb_off) - prev[i] *= DSP::polar(1, tse(i+code_off)); + chan[i] *= DSP::polar(1, tse(i+code_off)); std::cerr << "."; } std::cerr << " done" << std::endl; diff --git a/encode.cc b/encode.cc index 0ab3bf6..508965e 100644 --- a/encode.cc +++ b/encode.cc @@ -21,7 +21,7 @@ Copyright 2021 Ahmet Inan #include "qam.hh" #include "polar_tables.hh" #include "polar_encoder.hh" -#include "bose_chaudhuri_hocquenghem_encoder.hh" +#include "hadamard_encoder.hh" template struct Encoder @@ -35,24 +35,22 @@ struct Encoder static const int mls0_len = 320; static const int mls0_poly = 0b1100110001; static const int mls0_seed = 214; - static const int mls1_len = 255; static const int mls1_poly = 0b100101011; static const int mls2_poly = 0b100101010001; DSP::WritePCM *pcm; DSP::FastFourierTransform fwd; DSP::FastFourierTransform bwd; - CODE::CRC crc0; CODE::CRC crc1; - CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc; + CODE::HadamardEncoder<6> hadamardenc; CODE::PolarEncoder polarenc; uint8_t input_data[data_max]; code_type code[bits_max], perm[bits_max], mesg[bits_max]; + int8_t mode[32]; cmplx fdom[symbol_len]; cmplx tdom[symbol_len]; cmplx temp[symbol_len]; cmplx kern[symbol_len]; cmplx guard[guard_len]; - cmplx prev[cols_max]; value weight[guard_len]; value papr_min, papr_max; int mod_bits; @@ -62,7 +60,6 @@ struct Encoder int cons_cols; int cons_rows; int mls0_off; - int mls1_off; static int bin(int carrier) { @@ -113,7 +110,7 @@ struct Encoder void symbol(bool papr_reduction = true, bool guard_interval = true) { bwd(tdom, fdom); - value scale = 2; + value scale = 2 / std::sqrt(value(symbol_len) / value(cons_cols)); for (int i = 0; i < symbol_len; ++i) tdom[i] /= scale * std::sqrt(value(symbol_len)); clipping_and_filtering(scale, oper_mode > 0 && papr_reduction); @@ -145,56 +142,22 @@ struct Encoder void pilot_block() { CODE::MLS seq2(mls2_poly); - value code_fac = std::sqrt(value(symbol_len) / value(cons_cols)); for (int i = 0; i < symbol_len; ++i) fdom[i] = 0; for (int i = code_off; i < code_off + cons_cols; ++i) - fdom[bin(i)] = code_fac * nrz(seq2()); + fdom[bin(i)] = nrz(seq2()); symbol(); } void schmidl_cox() { CODE::MLS seq0(mls0_poly, mls0_seed); - value mls0_fac = std::sqrt(value(symbol_len) / value(mls0_len)); for (int i = 0; i < symbol_len; ++i) fdom[i] = 0; for (int i = 0; i < mls0_len; ++i) - fdom[bin(i+mls0_off)] = mls0_fac * nrz(seq0()); + fdom[bin(i+mls0_off)] = nrz(seq0()); symbol(false); symbol(false, false); } - void meta_data(uint64_t md) - { - uint8_t data[9] = { 0 }, parity[23] = { 0 }; - for (int i = 0; i < 55; ++i) - CODE::set_be_bit(data, i, (md>>i)&1); - crc0.reset(); - uint16_t cs = crc0(md << 9); - for (int i = 0; i < 16; ++i) - CODE::set_be_bit(data, i+55, (cs>>i)&1); - bchenc(data, parity); - CODE::MLS seq1(mls1_poly); - value cons_fac = std::sqrt(value(symbol_len) / value(cons_cols)); - for (int i = 0; i < symbol_len; ++i) - fdom[i] = 0; - fdom[bin(mls1_off-1)] = cons_fac; - for (int i = 0; i < 71; ++i) - fdom[bin(i+mls1_off)] = nrz(CODE::get_be_bit(data, i)); - for (int i = 71; i < mls1_len; ++i) - fdom[bin(i+mls1_off)] = nrz(CODE::get_be_bit(parity, i-71)); - for (int i = 0; i < mls1_len; ++i) - fdom[bin(i+mls1_off)] *= fdom[bin(i-1+mls1_off)]; - for (int i = 0; i < mls1_len; ++i) - fdom[bin(i+mls1_off)] *= nrz(seq1()); - if (oper_mode > 0) { - for (int i = code_off; i < code_off + cons_cols; ++i) { - if (i == mls1_off-1) - i += mls1_len + 1; - fdom[bin(i)] = cons_fac * nrz(seq1()); - } - } - symbol(); - } cmplx mod_map(code_type *b) { switch (mod_bits) { @@ -253,15 +216,8 @@ struct Encoder dest[i] = src[seq()]; } } - Encoder(DSP::WritePCM *pcm, const char *const *input_names, int input_count, int freq_off, uint64_t call_sign, int oper_mode) : - pcm(pcm), crc0(0xA8F4), crc1(0x8F6E37A0), bchenc({ - 0b100011101, 0b101110111, 0b111110011, 0b101101001, - 0b110111101, 0b111100111, 0b100101011, 0b111010111, - 0b000010011, 0b101100101, 0b110001011, 0b101100011, - 0b100011011, 0b100111111, 0b110001101, 0b100101101, - 0b101011111, 0b111111001, 0b111000011, 0b100111001, - 0b110101001, 0b000011111, 0b110000111, 0b110110001}), - oper_mode(oper_mode) + Encoder(DSP::WritePCM *pcm, const char *const *input_names, int input_count, int freq_off, int oper_mode) : + pcm(pcm), crc1(0x8F6E37A0), oper_mode(oper_mode) { const uint32_t *frozen_bits = nullptr; int code_cols = 256; @@ -272,59 +228,59 @@ struct Encoder int reserved_tones = 32; switch (oper_mode) { case 0: - comb_cols = 0; + cons_rows = 1; reserved_tones = 0; break; - case 23: + case 1: mod_bits = 2; cons_rows = 8; code_order = 12; data_bits = 2048; frozen_bits = frozen_4096_2080; break; - case 24: + case 2: mod_bits = 2; cons_rows = 16; code_order = 13; data_bits = 4096; frozen_bits = frozen_8192_4128; break; - case 25: + case 3: mod_bits = 2; cons_rows = 32; code_order = 14; data_bits = 8192; frozen_bits = frozen_16384_8224; break; - case 26: + case 4: mod_bits = 4; cons_rows = 4; code_order = 12; data_bits = 2048; frozen_bits = frozen_4096_2080; break; - case 27: + case 5: mod_bits = 4; cons_rows = 8; code_order = 13; data_bits = 4096; frozen_bits = frozen_8192_4128; break; - case 28: + case 6: mod_bits = 4; cons_rows = 16; code_order = 14; data_bits = 8192; frozen_bits = frozen_16384_8224; break; - case 29: + case 7: mod_bits = 6; cons_rows = 6; code_order = 13; data_bits = 4096; frozen_bits = frozen_8192_4128; break; - case 30: + case 8: mod_bits = 6; cons_rows = 11; code_order = 14; @@ -337,15 +293,14 @@ struct Encoder int data_bytes = data_bits / 8; int offset = (freq_off * symbol_len) / rate; mls0_off = offset - mls0_len / 2; - mls1_off = offset - mls1_len / 2; cons_cols = code_cols + comb_cols; code_off = offset - cons_cols / 2; if (oper_mode > 0) { - value kern_fac = 1 / value(10 * reserved_tones); + value mag = 1 / value(10 * reserved_tones); for (int i = 0, j = code_off - reserved_tones / 2; i < reserved_tones; ++i, ++j) { if (j == code_off) j += cons_cols; - fdom[bin(j)] = kern_fac; + fdom[bin(j)] = mag; } bwd(kern, fdom); } @@ -359,9 +314,18 @@ struct Encoder weight[i] = 1; papr_min = 1000, papr_max = -1000; pilot_block(); + hadamardenc(mode, oper_mode); if (!oper_mode) { schmidl_cox(); - meta_data(call_sign << 8); + CODE::MLS seq1(mls1_poly); + for (int i = 0, m = 0; i < cons_cols; ++i) { + if (i % comb_dist == comb_off) { + fdom[bin(i+code_off)] = nrz(seq1()) * mode[m++]; + } else { + fdom[bin(i+code_off)] = 0; + } + } + symbol(false); } for (int input_index = 0; input_index < input_count; ++input_index) { const char *input_name = input_names[input_index]; @@ -378,7 +342,6 @@ struct Encoder for (int i = 0; i < data_bytes; ++i) input_data[i] ^= scrambler(); schmidl_cox(); - meta_data((call_sign << 8) | oper_mode); for (int i = 0; i < data_bits; ++i) mesg[i] = nrz(CODE::get_le_bit(input_data, i)); crc1.reset(); @@ -388,16 +351,13 @@ struct Encoder mesg[i+data_bits] = nrz((crc1()>>i)&1); polarenc(code, mesg, frozen_bits, code_order); shuffle(perm, code); - for (int i = 0; i < cons_cols; ++i) - prev[i] = fdom[bin(i+code_off)]; - CODE::MLS seq0(mls0_poly); + CODE::MLS seq1(mls1_poly); for (int j = 0, k = 0; j < cons_rows; ++j) { - for (int i = 0; i < cons_cols; ++i) { + for (int i = 0, m = 0; i < cons_cols; ++i) { if (i % comb_dist == comb_off) { - prev[i] *= nrz(seq0()); - fdom[bin(i+code_off)] = prev[i]; + fdom[bin(i+code_off)] = nrz(seq1()) * mode[m++]; } else { - fdom[bin(i+code_off)] = prev[i] * mod_map(perm+k); + fdom[bin(i+code_off)] = mod_map(perm+k); k += mod_bits; } } @@ -411,27 +371,10 @@ struct Encoder } }; -long long int base37_encoder(const char *str) -{ - long long int acc = 0; - for (char c = *str++; c; c = *str++) { - acc *= 37; - if (c >= '0' && c <= '9') - acc += c - '0' + 1; - else if (c >= 'a' && c <= 'z') - acc += c - 'a' + 11; - else if (c >= 'A' && c <= 'Z') - acc += c - 'A' + 11; - else if (c != ' ') - return -1; - } - return acc; -} - int main(int argc, char **argv) { - if (argc < 8) { - std::cerr << "usage: " << argv[0] << " OUTPUT RATE BITS CHANNELS OFFSET MODE CALLSIGN INPUT.." << std::endl; + if (argc < 7) { + std::cerr << "usage: " << argv[0] << " OUTPUT RATE BITS CHANNELS OFFSET MODE INPUT.." << std::endl; return 1; } @@ -447,19 +390,13 @@ int main(int argc, char **argv) std::cerr << "Frequency offset must be divisible by 50." << std::endl; return 1; } - int input_count = argc - 8; + int input_count = argc - 7; int oper_mode = std::atoi(argv[6]); if (!oper_mode != !input_count) { std::cerr << "Using operation mode " << oper_mode << " but " << input_count << " input file" << (input_count == 1 ? "" : "s") << " provided." << std::endl; return 1; } - long long int call_sign = base37_encoder(argv[7]); - if (call_sign <= 0 || call_sign >= 129961739795077L) { - std::cerr << "Unsupported call sign." << std::endl; - return 1; - } - - if (oper_mode && (oper_mode < 23 || oper_mode > 30)) { + if (oper_mode < 0 || oper_mode > 8) { std::cerr << "Unsupported operation mode." << std::endl; return 1; } @@ -474,16 +411,16 @@ int main(int argc, char **argv) output_file.silence(output_rate); switch (output_rate) { case 8000: - delete new Encoder(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode); + delete new Encoder(&output_file, argv+7, input_count, freq_off, oper_mode); break; case 16000: - delete new Encoder(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode); + delete new Encoder(&output_file, argv+7, input_count, freq_off, oper_mode); break; case 44100: - delete new Encoder(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode); + delete new Encoder(&output_file, argv+7, input_count, freq_off, oper_mode); break; case 48000: - delete new Encoder(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode); + delete new Encoder(&output_file, argv+7, input_count, freq_off, oper_mode); break; default: std::cerr << "Unsupported sample rate." << std::endl;