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https://github.com/aicodix/modem.git
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use the first 32 comb pilots to signal the mode
This commit is contained in:
Ahmet Inan
parent
4430de392b
commit
4b99f82aac
2 changed files with 99 additions and 215 deletions
145
encode.cc
145
encode.cc
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@ -21,7 +21,7 @@ Copyright 2021 Ahmet Inan <inan@aicodix.de>
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#include "qam.hh"
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#include "polar_tables.hh"
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#include "polar_encoder.hh"
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#include "bose_chaudhuri_hocquenghem_encoder.hh"
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#include "hadamard_encoder.hh"
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template <typename value, typename cmplx, int rate>
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struct Encoder
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@ -35,24 +35,22 @@ struct Encoder
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static const int mls0_len = 320;
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static const int mls0_poly = 0b1100110001;
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static const int mls0_seed = 214;
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static const int mls1_len = 255;
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static const int mls1_poly = 0b100101011;
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static const int mls2_poly = 0b100101010001;
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DSP::WritePCM<value> *pcm;
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DSP::FastFourierTransform<symbol_len, cmplx, -1> fwd;
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DSP::FastFourierTransform<symbol_len, cmplx, 1> bwd;
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CODE::CRC<uint16_t> crc0;
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CODE::CRC<uint32_t> crc1;
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CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc;
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CODE::HadamardEncoder<6> hadamardenc;
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CODE::PolarEncoder<code_type> polarenc;
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uint8_t input_data[data_max];
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code_type code[bits_max], perm[bits_max], mesg[bits_max];
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int8_t mode[32];
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cmplx fdom[symbol_len];
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cmplx tdom[symbol_len];
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cmplx temp[symbol_len];
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cmplx kern[symbol_len];
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cmplx guard[guard_len];
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cmplx prev[cols_max];
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value weight[guard_len];
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value papr_min, papr_max;
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int mod_bits;
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@ -62,7 +60,6 @@ struct Encoder
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int cons_cols;
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int cons_rows;
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int mls0_off;
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int mls1_off;
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static int bin(int carrier)
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{
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@ -113,7 +110,7 @@ struct Encoder
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void symbol(bool papr_reduction = true, bool guard_interval = true)
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{
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bwd(tdom, fdom);
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value scale = 2;
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value scale = 2 / std::sqrt(value(symbol_len) / value(cons_cols));
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for (int i = 0; i < symbol_len; ++i)
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tdom[i] /= scale * std::sqrt(value(symbol_len));
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clipping_and_filtering(scale, oper_mode > 0 && papr_reduction);
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@ -145,56 +142,22 @@ struct Encoder
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void pilot_block()
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{
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CODE::MLS seq2(mls2_poly);
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value code_fac = std::sqrt(value(symbol_len) / value(cons_cols));
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for (int i = 0; i < symbol_len; ++i)
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fdom[i] = 0;
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for (int i = code_off; i < code_off + cons_cols; ++i)
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fdom[bin(i)] = code_fac * nrz(seq2());
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fdom[bin(i)] = nrz(seq2());
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symbol();
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}
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void schmidl_cox()
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{
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CODE::MLS seq0(mls0_poly, mls0_seed);
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value mls0_fac = std::sqrt(value(symbol_len) / value(mls0_len));
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for (int i = 0; i < symbol_len; ++i)
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fdom[i] = 0;
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for (int i = 0; i < mls0_len; ++i)
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fdom[bin(i+mls0_off)] = mls0_fac * nrz(seq0());
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fdom[bin(i+mls0_off)] = nrz(seq0());
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symbol(false);
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symbol(false, false);
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}
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void meta_data(uint64_t md)
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{
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uint8_t data[9] = { 0 }, parity[23] = { 0 };
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for (int i = 0; i < 55; ++i)
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CODE::set_be_bit(data, i, (md>>i)&1);
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crc0.reset();
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uint16_t cs = crc0(md << 9);
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for (int i = 0; i < 16; ++i)
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CODE::set_be_bit(data, i+55, (cs>>i)&1);
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bchenc(data, parity);
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CODE::MLS seq1(mls1_poly);
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value cons_fac = std::sqrt(value(symbol_len) / value(cons_cols));
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for (int i = 0; i < symbol_len; ++i)
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fdom[i] = 0;
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fdom[bin(mls1_off-1)] = cons_fac;
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for (int i = 0; i < 71; ++i)
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fdom[bin(i+mls1_off)] = nrz(CODE::get_be_bit(data, i));
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for (int i = 71; i < mls1_len; ++i)
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fdom[bin(i+mls1_off)] = nrz(CODE::get_be_bit(parity, i-71));
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for (int i = 0; i < mls1_len; ++i)
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fdom[bin(i+mls1_off)] *= fdom[bin(i-1+mls1_off)];
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for (int i = 0; i < mls1_len; ++i)
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fdom[bin(i+mls1_off)] *= nrz(seq1());
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if (oper_mode > 0) {
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for (int i = code_off; i < code_off + cons_cols; ++i) {
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if (i == mls1_off-1)
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i += mls1_len + 1;
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fdom[bin(i)] = cons_fac * nrz(seq1());
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}
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}
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symbol();
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}
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cmplx mod_map(code_type *b)
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{
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switch (mod_bits) {
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@ -253,15 +216,8 @@ struct Encoder
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dest[i] = src[seq()];
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}
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}
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Encoder(DSP::WritePCM<value> *pcm, const char *const *input_names, int input_count, int freq_off, uint64_t call_sign, int oper_mode) :
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pcm(pcm), crc0(0xA8F4), crc1(0x8F6E37A0), bchenc({
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0b100011101, 0b101110111, 0b111110011, 0b101101001,
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0b110111101, 0b111100111, 0b100101011, 0b111010111,
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0b000010011, 0b101100101, 0b110001011, 0b101100011,
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0b100011011, 0b100111111, 0b110001101, 0b100101101,
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0b101011111, 0b111111001, 0b111000011, 0b100111001,
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0b110101001, 0b000011111, 0b110000111, 0b110110001}),
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oper_mode(oper_mode)
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Encoder(DSP::WritePCM<value> *pcm, const char *const *input_names, int input_count, int freq_off, int oper_mode) :
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pcm(pcm), crc1(0x8F6E37A0), oper_mode(oper_mode)
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{
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const uint32_t *frozen_bits = nullptr;
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int code_cols = 256;
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@ -272,59 +228,59 @@ struct Encoder
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int reserved_tones = 32;
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switch (oper_mode) {
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case 0:
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comb_cols = 0;
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cons_rows = 1;
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reserved_tones = 0;
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break;
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case 23:
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case 1:
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mod_bits = 2;
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cons_rows = 8;
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code_order = 12;
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data_bits = 2048;
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frozen_bits = frozen_4096_2080;
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break;
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case 24:
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case 2:
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mod_bits = 2;
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cons_rows = 16;
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code_order = 13;
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data_bits = 4096;
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frozen_bits = frozen_8192_4128;
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break;
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case 25:
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case 3:
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mod_bits = 2;
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cons_rows = 32;
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code_order = 14;
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data_bits = 8192;
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frozen_bits = frozen_16384_8224;
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break;
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case 26:
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case 4:
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mod_bits = 4;
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cons_rows = 4;
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code_order = 12;
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data_bits = 2048;
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frozen_bits = frozen_4096_2080;
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break;
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case 27:
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case 5:
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mod_bits = 4;
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cons_rows = 8;
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code_order = 13;
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data_bits = 4096;
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frozen_bits = frozen_8192_4128;
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break;
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case 28:
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case 6:
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mod_bits = 4;
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cons_rows = 16;
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code_order = 14;
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data_bits = 8192;
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frozen_bits = frozen_16384_8224;
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break;
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case 29:
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case 7:
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mod_bits = 6;
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cons_rows = 6;
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code_order = 13;
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data_bits = 4096;
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frozen_bits = frozen_8192_4128;
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break;
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case 30:
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case 8:
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mod_bits = 6;
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cons_rows = 11;
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code_order = 14;
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@ -337,15 +293,14 @@ struct Encoder
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int data_bytes = data_bits / 8;
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int offset = (freq_off * symbol_len) / rate;
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mls0_off = offset - mls0_len / 2;
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mls1_off = offset - mls1_len / 2;
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cons_cols = code_cols + comb_cols;
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code_off = offset - cons_cols / 2;
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if (oper_mode > 0) {
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value kern_fac = 1 / value(10 * reserved_tones);
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value mag = 1 / value(10 * reserved_tones);
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for (int i = 0, j = code_off - reserved_tones / 2; i < reserved_tones; ++i, ++j) {
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if (j == code_off)
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j += cons_cols;
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fdom[bin(j)] = kern_fac;
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fdom[bin(j)] = mag;
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}
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bwd(kern, fdom);
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}
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@ -359,9 +314,18 @@ struct Encoder
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weight[i] = 1;
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papr_min = 1000, papr_max = -1000;
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pilot_block();
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hadamardenc(mode, oper_mode);
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if (!oper_mode) {
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schmidl_cox();
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meta_data(call_sign << 8);
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CODE::MLS seq1(mls1_poly);
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for (int i = 0, m = 0; i < cons_cols; ++i) {
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if (i % comb_dist == comb_off) {
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fdom[bin(i+code_off)] = nrz(seq1()) * mode[m++];
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} else {
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fdom[bin(i+code_off)] = 0;
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}
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}
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symbol(false);
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}
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for (int input_index = 0; input_index < input_count; ++input_index) {
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const char *input_name = input_names[input_index];
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@ -378,7 +342,6 @@ struct Encoder
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for (int i = 0; i < data_bytes; ++i)
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input_data[i] ^= scrambler();
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schmidl_cox();
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meta_data((call_sign << 8) | oper_mode);
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for (int i = 0; i < data_bits; ++i)
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mesg[i] = nrz(CODE::get_le_bit(input_data, i));
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crc1.reset();
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@ -388,16 +351,13 @@ struct Encoder
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mesg[i+data_bits] = nrz((crc1()>>i)&1);
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polarenc(code, mesg, frozen_bits, code_order);
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shuffle(perm, code);
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for (int i = 0; i < cons_cols; ++i)
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prev[i] = fdom[bin(i+code_off)];
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CODE::MLS seq0(mls0_poly);
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CODE::MLS seq1(mls1_poly);
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for (int j = 0, k = 0; j < cons_rows; ++j) {
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for (int i = 0; i < cons_cols; ++i) {
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for (int i = 0, m = 0; i < cons_cols; ++i) {
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if (i % comb_dist == comb_off) {
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prev[i] *= nrz(seq0());
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fdom[bin(i+code_off)] = prev[i];
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fdom[bin(i+code_off)] = nrz(seq1()) * mode[m++];
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} else {
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fdom[bin(i+code_off)] = prev[i] * mod_map(perm+k);
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fdom[bin(i+code_off)] = mod_map(perm+k);
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k += mod_bits;
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}
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}
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@ -411,27 +371,10 @@ struct Encoder
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}
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};
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long long int base37_encoder(const char *str)
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{
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long long int acc = 0;
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for (char c = *str++; c; c = *str++) {
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acc *= 37;
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if (c >= '0' && c <= '9')
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acc += c - '0' + 1;
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else if (c >= 'a' && c <= 'z')
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acc += c - 'a' + 11;
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else if (c >= 'A' && c <= 'Z')
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acc += c - 'A' + 11;
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else if (c != ' ')
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return -1;
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}
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return acc;
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}
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int main(int argc, char **argv)
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{
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if (argc < 8) {
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std::cerr << "usage: " << argv[0] << " OUTPUT RATE BITS CHANNELS OFFSET MODE CALLSIGN INPUT.." << std::endl;
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if (argc < 7) {
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std::cerr << "usage: " << argv[0] << " OUTPUT RATE BITS CHANNELS OFFSET MODE INPUT.." << std::endl;
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return 1;
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}
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@ -447,19 +390,13 @@ int main(int argc, char **argv)
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std::cerr << "Frequency offset must be divisible by 50." << std::endl;
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return 1;
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}
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int input_count = argc - 8;
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int input_count = argc - 7;
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int oper_mode = std::atoi(argv[6]);
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if (!oper_mode != !input_count) {
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std::cerr << "Using operation mode " << oper_mode << " but " << input_count << " input file" << (input_count == 1 ? "" : "s") << " provided." << std::endl;
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return 1;
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}
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long long int call_sign = base37_encoder(argv[7]);
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if (call_sign <= 0 || call_sign >= 129961739795077L) {
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std::cerr << "Unsupported call sign." << std::endl;
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return 1;
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}
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if (oper_mode && (oper_mode < 23 || oper_mode > 30)) {
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if (oper_mode < 0 || oper_mode > 8) {
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std::cerr << "Unsupported operation mode." << std::endl;
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return 1;
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}
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@ -474,16 +411,16 @@ int main(int argc, char **argv)
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output_file.silence(output_rate);
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switch (output_rate) {
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case 8000:
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delete new Encoder<value, cmplx, 8000>(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode);
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delete new Encoder<value, cmplx, 8000>(&output_file, argv+7, input_count, freq_off, oper_mode);
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break;
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case 16000:
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delete new Encoder<value, cmplx, 16000>(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode);
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delete new Encoder<value, cmplx, 16000>(&output_file, argv+7, input_count, freq_off, oper_mode);
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break;
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case 44100:
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delete new Encoder<value, cmplx, 44100>(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode);
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delete new Encoder<value, cmplx, 44100>(&output_file, argv+7, input_count, freq_off, oper_mode);
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break;
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case 48000:
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delete new Encoder<value, cmplx, 48000>(&output_file, argv+8, input_count, freq_off, call_sign, oper_mode);
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delete new Encoder<value, cmplx, 48000>(&output_file, argv+7, input_count, freq_off, oper_mode);
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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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