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use a shortened systematic polar code and CA-SCL decoding

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using SPC(64800, 43072):
mode 6: 8PSK, 2700 Hz BW and about 10 seconds long
mode 7: 8PSK, 2500 Hz BW and about 11 seconds long
mode 8: QPSK, 2500 Hz BW and about 16 seconds long
mode 9: QPSK, 2250 Hz BW and about 18 seconds long

using SPC(64512, 43072):
mode 10: 8PSK, 3200 Hz BW and about 9 seconds long
mode 11: 8PSK, 2400 Hz BW and about 11 seconds long
mode 12: QPSK, 2400 Hz BW and about 16 seconds long
mode 13: QPSK, 1600 Hz BW and about 24 seconds long
This commit is contained in:
Ahmet Inan 2021-07-22 21:23:16 +02:00
commit 99b6a4e963
7 changed files with 339 additions and 325 deletions
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1
.gitignore vendored
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@ -4,3 +4,4 @@
*.dat *.dat
encode encode
decode decode
freezer

5
Makefile
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@ -20,8 +20,11 @@ encode: encode.cc
decode: decode.cc decode: decode.cc
$(CXX) $(CXXFLAGS) $< -o $@ $(CXX) $(CXXFLAGS) $< -o $@
freezer: freezer.cc
$(CXX) $(CXXFLAGS) $< -o $@
.PHONY: clean .PHONY: clean
clean: clean:
rm -f encode decode rm -f encode decode freezer

273
decode.cc
View file

@ -28,10 +28,10 @@ namespace DSP { using std::abs; using std::min; using std::cos; using std::sin;
#include "crc.hh" #include "crc.hh"
#include "osd.hh" #include "osd.hh"
#include "psk.hh" #include "psk.hh"
#include "ldpc_tables.hh" #include "polar_tables.hh"
#include "ldpc_decoder.hh" #include "polar_helper.hh"
#include "galois_field.hh" #include "polar_encoder.hh"
#include "bose_chaudhuri_hocquenghem_decoder.hh" #include "polar_list_decoder.hh"
template <typename value, typename cmplx, int search_pos, int symbol_len, int guard_len> template <typename value, typename cmplx, int search_pos, int symbol_len, int guard_len>
struct SchmidlCox struct SchmidlCox
@ -160,17 +160,22 @@ void base37_decoder(char *str, long long int val, int len)
template <typename value, typename cmplx, int rate> template <typename value, typename cmplx, int rate>
struct Decoder struct Decoder
{ {
typedef float code_type;
#ifdef __AVX2__
typedef SIMD<code_type, 32 / sizeof(code_type)> mesg_type;
#else
typedef SIMD<code_type, 16 / sizeof(code_type)> mesg_type;
#endif
typedef DSP::Const<value> Const; typedef DSP::Const<value> Const;
static const int symbol_len = (1280 * rate) / 8000; static const int symbol_len = (1280 * rate) / 8000;
static const int filter_len = (((21 * rate) / 8000) & ~3) | 1; static const int filter_len = (((21 * rate) / 8000) & ~3) | 1;
static const int guard_len = symbol_len / 8; static const int guard_len = symbol_len / 8;
static const int ldpc_bits = 64800; static const int data_bits = 43040;
static const int bch_bits = ldpc_bits - 21600; static const int crc_bits = data_bits + 32;
static const int data_bits = bch_bits - 10 * 16;
static const int mod_min = 2; static const int mod_min = 2;
static const int mod_max = 3; static const int mod_max = 3;
static const int cons_max = ldpc_bits / mod_min; static const int cons_max = 64800 / mod_min;
static const int cols_min = 360; static const int cols_min = 256;
static const int rows_max = cons_max / cols_min; static const int rows_max = cons_max / cols_min;
static const int mls0_len = 127; static const int mls0_len = 127;
static const int mls0_off = - mls0_len + 1; static const int mls0_off = - mls0_len + 1;
@ -189,21 +194,24 @@ struct Decoder
DSP::BipBuffer<cmplx, buffer_len> input_hist; DSP::BipBuffer<cmplx, buffer_len> input_hist;
SchmidlCox<value, cmplx, search_pos, symbol_len/2, guard_len> correlator; SchmidlCox<value, cmplx, search_pos, symbol_len/2, guard_len> correlator;
CODE::CRC<uint16_t> crc0; CODE::CRC<uint16_t> crc0;
typedef CODE::GaloisField<16, 0b10000000000101101, uint16_t> GF; CODE::CRC<uint32_t> crc1;
GF gf;
CODE::BoseChaudhuriHocquenghemDecoder<20, 1, 65375, GF> bchdec1;
CODE::OrderedStatisticsDecoder<255, 71, 4> osddec; CODE::OrderedStatisticsDecoder<255, 71, 4> osddec;
CODE::LDPCDecoder<DVB_T2_TABLE_A3, 1> ldpcdec; CODE::PolarEncoder<mesg_type> polarenc;
CODE::PolarListDecoder<mesg_type, 16> polardec;
int8_t genmat[255*71]; int8_t genmat[255*71];
int8_t code[ldpc_bits], bint[ldpc_bits]; mesg_type mesg[44096], mess[65536];
uint16_t erasures[20]; code_type code[65536];
cmplx head[symbol_len], tail[symbol_len], cons[cons_max]; cmplx head[symbol_len], tail[symbol_len], cons[cons_max];
cmplx fdom[symbol_len], tdom[buffer_len], resam[buffer_len]; cmplx fdom[symbol_len], tdom[buffer_len], resam[buffer_len];
value cfo_rad, sfo_rad; value cfo_rad, sfo_rad;
const uint32_t *frozen_bits;
int code_order;
int symbol_pos; int symbol_pos;
int oper_mode; int oper_mode;
int mod_bits; int mod_bits;
int cons_cnt; int cons_cnt;
int cons_bits;
int mesg_bits;
static int bin(int carrier) static int bin(int carrier)
{ {
@ -253,58 +261,75 @@ struct Decoder
sum += samples[i] * conj(samples[i+symbol_len/2]); sum += samples[i] * conj(samples[i+symbol_len/2]);
return arg(sum) / (symbol_len/2); return arg(sum) / (symbol_len/2);
} }
void deinterleave() void lengthen()
{ {
for (int i = 0; i < cons_cnt; ++i) int code_bits = 1 << code_order;
for (int k = 0; k < mod_bits; ++k) for (int i = code_bits-1, j = cons_bits-1, k = mesg_bits-1; i >= 0; --i)
code[cons_cnt*k+i] = bint[mod_bits*i+k]; if ((frozen_bits[i/32] >> (i%32)) & 1 || k-- < crc_bits)
code[i] = code[j--];
else
code[i] = CODE::PolarHelper<code_type>::quant(9000);
} }
void interleave() void systematic()
{ {
for (int i = 0; i < cons_cnt; ++i) polarenc(mess, mesg, frozen_bits, code_order);
for (int k = 0; k < mod_bits; ++k) int code_bits = 1 << code_order;
bint[mod_bits*i+k] = code[cons_cnt*k+i]; for (int i = 0, j = 0; i < code_bits && j < mesg_bits; ++i)
if (!((frozen_bits[i/32] >> (i%32)) & 1))
mesg[j++] = mess[i];
} }
cmplx mod_map(int8_t *b) cmplx mod_map(code_type *b)
{ {
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
case 3: case 7:
return PhaseShiftKeying<8, cmplx, int8_t>::map(b); case 10:
case 4: case 11:
case 5: return PhaseShiftKeying<8, cmplx, code_type>::map(b);
return PhaseShiftKeying<4, cmplx, int8_t>::map(b); case 8:
case 9:
case 12:
case 13:
return PhaseShiftKeying<4, cmplx, code_type>::map(b);
} }
return 0; return 0;
} }
void mod_hard(int8_t *b, cmplx c) void mod_hard(code_type *b, cmplx c)
{ {
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
case 3: case 7:
PhaseShiftKeying<8, cmplx, int8_t>::hard(b, c); case 10:
case 11:
PhaseShiftKeying<8, cmplx, code_type>::hard(b, c);
break; break;
case 4: case 8:
case 5: case 9:
PhaseShiftKeying<4, cmplx, int8_t>::hard(b, c); case 12:
case 13:
PhaseShiftKeying<4, cmplx, code_type>::hard(b, c);
break; break;
} }
} }
void mod_soft(int8_t *b, cmplx c, value precision) void mod_soft(code_type *b, cmplx c, value precision)
{ {
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
case 3: case 7:
PhaseShiftKeying<8, cmplx, int8_t>::soft(b, c, precision); case 10:
case 11:
PhaseShiftKeying<8, cmplx, code_type>::soft(b, c, precision);
break; break;
case 4: case 8:
case 5: case 9:
PhaseShiftKeying<4, cmplx, int8_t>::soft(b, c, precision); case 12:
case 13:
PhaseShiftKeying<4, cmplx, code_type>::soft(b, c, precision);
break; break;
} }
} }
Decoder(uint8_t *out, DSP::ReadPCM<value> *pcm, int skip_count) : Decoder(uint8_t *out, DSP::ReadPCM<value> *pcm, int skip_count) :
pcm(pcm), resample(rate, (rate * 19) / 40, 2), correlator(mls0_seq()), crc0(0xA8F4) pcm(pcm), resample(rate, (rate * 19) / 40, 2), correlator(mls0_seq()), crc0(0xA8F4), crc1(0xD419CC15)
{ {
CODE::BoseChaudhuriHocquenghemGenerator<255, 71>::matrix(genmat, true, { CODE::BoseChaudhuriHocquenghemGenerator<255, 71>::matrix(genmat, true, {
0b100011101, 0b101110111, 0b111110011, 0b101101001, 0b100011101, 0b101110111, 0b111110011, 0b101101001,
@ -366,29 +391,77 @@ struct Decoder
return; return;
} }
oper_mode = md & 255; oper_mode = md & 255;
int code_cols; int cons_cols;
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
code_cols = 432; cons_cols = 432;
mod_bits = 3; mod_bits = 3;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break; break;
case 3: case 7:
code_cols = 400; cons_cols = 400;
mod_bits = 3; mod_bits = 3;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break; break;
case 4: case 8:
code_cols = 400; cons_cols = 400;
mod_bits = 2; mod_bits = 2;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break; break;
case 5: case 9:
code_cols = 360; cons_cols = 360;
mod_bits = 2; mod_bits = 2;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break;
case 10:
cons_cols = 512;
mod_bits = 3;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break;
case 11:
cons_cols = 384;
mod_bits = 3;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break;
case 12:
cons_cols = 384;
mod_bits = 2;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break;
case 13:
cons_cols = 256;
mod_bits = 2;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break; break;
default: default:
std::cerr << "operation mode " << oper_mode << " unsupported." << std::endl; std::cerr << "operation mode " << oper_mode << " unsupported." << std::endl;
return; return;
} }
cons_cnt = ldpc_bits / mod_bits; cons_cnt = cons_bits / mod_bits;
std::cerr << "oper mode: " << oper_mode << std::endl; std::cerr << "oper mode: " << oper_mode << std::endl;
if ((md>>8) == 0 || (md>>8) >= 129961739795077L) { if ((md>>8) == 0 || (md>>8) >= 129961739795077L) {
std::cerr << "call sign unsupported." << std::endl; std::cerr << "call sign unsupported." << std::endl;
@ -399,11 +472,11 @@ struct Decoder
call_sign[9] = 0; call_sign[9] = 0;
std::cerr << "call sign: " << call_sign << std::endl; std::cerr << "call sign: " << call_sign << std::endl;
int code_rows = cons_cnt / code_cols; int cons_rows = cons_cnt / cons_cols;
int code_off = - code_cols / 2; int code_off = - cons_cols / 2;
int dis = displacement(buf+symbol_pos-(code_rows+1)*(symbol_len+guard_len), buf+symbol_pos+2*(symbol_len+guard_len)); int dis = displacement(buf+symbol_pos-(cons_rows+1)*(symbol_len+guard_len), buf+symbol_pos+2*(symbol_len+guard_len));
sfo_rad = (dis * Const::TwoPi()) / ((code_rows+3)*(symbol_len+guard_len)); sfo_rad = (dis * Const::TwoPi()) / ((cons_rows+3)*(symbol_len+guard_len));
std::cerr << "coarse sfo: " << 1000000 * sfo_rad / Const::TwoPi() << " ppm" << std::endl; std::cerr << "coarse sfo: " << 1000000 * sfo_rad / Const::TwoPi() << " ppm" << std::endl;
if (dis) { if (dis) {
value diff = sfo_rad * (rate / Const::TwoPi()); value diff = sfo_rad * (rate / Const::TwoPi());
@ -421,19 +494,19 @@ struct Decoder
for (int i = 0; i < buffer_len; ++i) for (int i = 0; i < buffer_len; ++i)
tdom[i] = resam[i] * osc(); tdom[i] = resam[i] * osc();
cmplx *cur = tdom + symbol_pos - (code_rows + 1) * (symbol_len + guard_len); cmplx *cur = tdom + symbol_pos - (cons_rows + 1) * (symbol_len + guard_len);
fwd(fdom, cur); fwd(fdom, cur);
for (int j = 0; j < code_rows; ++j) { for (int j = 0; j < cons_rows; ++j) {
for (int i = 0; i < code_cols; ++i) for (int i = 0; i < cons_cols; ++i)
head[bin(i+code_off)] = fdom[bin(i+code_off)]; head[bin(i+code_off)] = fdom[bin(i+code_off)];
fwd(fdom, cur += symbol_len+guard_len); fwd(fdom, cur += symbol_len+guard_len);
for (int i = 0; i < code_cols; ++i) for (int i = 0; i < cons_cols; ++i)
cons[code_cols*j+i] = demod_or_erase(fdom[bin(i+code_off)], head[bin(i+code_off)]); cons[cons_cols*j+i] = demod_or_erase(fdom[bin(i+code_off)], head[bin(i+code_off)]);
} }
if (1) { if (1) {
value sum = 0; value sum = 0;
for (int i = 0; i < cons_cnt; ++i) { for (int i = 0; i < cons_cnt; ++i) {
int8_t tmp[mod_max]; code_type tmp[mod_max];
mod_hard(tmp, cons[i]); mod_hard(tmp, cons[i]);
sum += arg(cons[i] * conj(mod_map(tmp))); sum += arg(cons[i] * conj(mod_map(tmp)));
} }
@ -448,7 +521,7 @@ struct Decoder
if (1) { if (1) {
value sp = 0, np = 0; value sp = 0, np = 0;
for (int i = 0; i < cons_cnt; ++i) { for (int i = 0; i < cons_cnt; ++i) {
int8_t tmp[mod_max]; code_type tmp[mod_max];
mod_hard(tmp, cons[i]); mod_hard(tmp, cons[i]);
cmplx hard = mod_map(tmp); cmplx hard = mod_map(tmp);
cmplx error = cons[i] - hard; cmplx error = cons[i] - hard;
@ -463,52 +536,31 @@ struct Decoder
precision = 1 / (sigma * sigma); precision = 1 / (sigma * sigma);
} }
for (int i = 0; i < cons_cnt; ++i) for (int i = 0; i < cons_cnt; ++i)
mod_soft(bint+mod_bits*i, cons[i], precision); mod_soft(code+mod_bits*i, cons[i], precision);
deinterleave(); lengthen();
int count = ldpcdec(code, code + bch_bits); CODE::PolarHelper<mesg_type>::PATH metric[mesg_type::SIZE];
if (count < 0) polardec(metric, mesg, code, frozen_bits, code_order);
std::cerr << "payload LDPC decoding did not converge." << std::endl; systematic();
if (1) { int order[mesg_type::SIZE];
interleave(); for (int k = 0; k < mesg_type::SIZE; ++k)
value sp = 0, np = 0; order[k] = k;
for (int i = 0; i < cons_cnt; ++i) { std::sort(order, order+mesg_type::SIZE, [metric](int a, int b){ return metric[a] < metric[b]; });
int8_t tmp[mod_max]; int best = -1;
for (int k = 0; k < mod_bits; ++k) for (int k = 0; k < mesg_type::SIZE; ++k) {
tmp[k] = nrz(bint[mod_bits*i+k] < 0); crc1.reset();
cmplx hard = mod_map(tmp); for (int i = 0; i < crc_bits; ++i)
cmplx error = cons[i] - hard; crc1(mesg[i].v[order[k]] < 0);
sp += norm(hard); if (crc1() == 0) {
np += norm(error); best = order[k];
break;
} }
value snr = DSP::decibel(sp / np);
std::cerr << "corr Es/N0: " << snr << " dB" << std::endl;
// $LLR=log(\frac{p(x=+1|y)}{p(x=-1|y)})$
// $p(x|\mu,\sigma)=\frac{1}{\sqrt{2\pi}\sigma}}e^{-\frac{(x-\mu)^2}{2\sigma^2}}$
value sigma = std::sqrt(np / (2 * sp));
precision = 1 / (sigma * sigma);
} }
for (int i = 0; i < bch_bits; ++i) if (best < 0) {
CODE::set_le_bit(out, i, code[i] < 0); std::cerr << "payload decoding error." << std::endl;
int ecnt = 0;
for (int i = 0; i < bch_bits; ++i) {
if (!code[i]) {
if (ecnt < 20) {
erasures[ecnt++] = i;
} else {
std::cerr << "payload LDPC produced more than 20 erasures." << std::endl;
return; return;
} }
} for (int i = 0; i < data_bits; ++i)
} CODE::set_le_bit(out, i, mesg[i].v[best] < 0);
if (ecnt)
std::cerr << "payload LDPC produced " << ecnt << " erasures." << std::endl;
int ret = bchdec1(out, out+data_bits/8, erasures, ecnt, data_bits);
if (ret < 0) {
std::cerr << "payload BCH error." << std::endl;
return;
}
if (ret)
std::cerr << "payload BCH corrected " << ret << " errors." << std::endl;
} }
}; };
@ -536,8 +588,8 @@ int main(int argc, char **argv)
if (argc > 3) if (argc > 3)
skip_count = std::atoi(argv[3]); skip_count = std::atoi(argv[3]);
const int code_len = 64800 / 8; const int data_len = 43040 / 8;
uint8_t *output_data = new uint8_t[code_len]; uint8_t *output_data = new uint8_t[data_len];
switch (input_file.rate()) { switch (input_file.rate()) {
case 8000: case 8000:
@ -562,7 +614,6 @@ int main(int argc, char **argv)
std::cerr << "Couldn't open file \"" << output_name << "\" for writing." << std::endl; std::cerr << "Couldn't open file \"" << output_name << "\" for writing." << std::endl;
return 1; return 1;
} }
const int data_len = code_len - (10 * 16 + 21600) / 8;
CODE::Xorshift32 scrambler; CODE::Xorshift32 scrambler;
for (int i = 0; i < data_len; ++i) for (int i = 0; i < data_len; ++i)
output_data[i] ^= scrambler(); output_data[i] ^= scrambler();

194
encode.cc
View file

@ -18,19 +18,19 @@ Copyright 2021 Ahmet Inan <inan@aicodix.de>
#include "mls.hh" #include "mls.hh"
#include "crc.hh" #include "crc.hh"
#include "psk.hh" #include "psk.hh"
#include "ldpc_tables.hh" #include "polar_tables.hh"
#include "ldpc_encoder.hh" #include "polar_helper.hh"
#include "galois_field.hh" #include "polar_encoder.hh"
#include "bose_chaudhuri_hocquenghem_encoder.hh" #include "bose_chaudhuri_hocquenghem_encoder.hh"
template <typename value, typename cmplx, int rate> template <typename value, typename cmplx, int rate>
struct Encoder struct Encoder
{ {
typedef int8_t code_type;
static const int symbol_len = (1280 * rate) / 8000; static const int symbol_len = (1280 * rate) / 8000;
static const int guard_len = symbol_len / 8; static const int guard_len = symbol_len / 8;
static const int ldpc_bits = 64800; static const int data_bits = 43040;
static const int bch_bits = ldpc_bits - 21600; static const int crc_bits = data_bits + 32;
static const int data_bits = bch_bits - 10 * 16;
static const int mls0_len = 127; static const int mls0_len = 127;
static const int mls0_poly = 0b10001001; static const int mls0_poly = 0b10001001;
static const int mls1_len = 255; static const int mls1_len = 255;
@ -41,20 +41,24 @@ struct Encoder
DSP::FastFourierTransform<4*symbol_len, cmplx, -1> fwd4; DSP::FastFourierTransform<4*symbol_len, cmplx, -1> fwd4;
DSP::FastFourierTransform<4*symbol_len, cmplx, 1> bwd4; DSP::FastFourierTransform<4*symbol_len, cmplx, 1> bwd4;
CODE::CRC<uint16_t> crc0; CODE::CRC<uint16_t> crc0;
CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc0; CODE::CRC<uint32_t> crc1;
CODE::BoseChaudhuriHocquenghemEncoder<65535, 65375> bchenc1; CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc;
CODE::LDPCEncoder<DVB_T2_TABLE_A3> ldpcenc; CODE::PolarSysEnc<code_type> polarenc;
int8_t code[ldpc_bits], bint[ldpc_bits]; code_type code[65536], mesg[44096];
cmplx fdom[symbol_len], fdom4[4*symbol_len]; cmplx fdom[symbol_len], fdom4[4*symbol_len];
cmplx tdom[symbol_len], tdom4[4*symbol_len]; cmplx tdom[symbol_len], tdom4[4*symbol_len];
cmplx temp[symbol_len]; cmplx temp[symbol_len];
cmplx guard[guard_len]; cmplx guard[guard_len];
cmplx papr_min, papr_max; cmplx papr_min, papr_max;
const uint32_t *frozen_bits;
int code_order;
int oper_mode; int oper_mode;
int mod_bits; int mod_bits;
int cons_cnt; int cons_cnt;
int code_cols; int cons_cols;
int code_rows; int cons_rows;
int cons_bits;
int mesg_bits;
int code_off; int code_off;
int mls0_off; int mls0_off;
int mls1_off; int mls1_off;
@ -126,10 +130,10 @@ struct Encoder
void pilot_block() void pilot_block()
{ {
CODE::MLS seq2(mls2_poly); CODE::MLS seq2(mls2_poly);
value code_fac = std::sqrt(value(symbol_len) / value(code_cols)); value code_fac = std::sqrt(value(symbol_len) / value(cons_cols));
for (int i = 0; i < symbol_len; ++i) for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0; fdom[i] = 0;
for (int i = code_off; i < code_off + code_cols; ++i) for (int i = code_off; i < code_off + cons_cols; ++i)
fdom[bin(i)] = code_fac * nrz(seq2()); fdom[bin(i)] = code_fac * nrz(seq2());
symbol(); symbol();
} }
@ -155,7 +159,7 @@ struct Encoder
uint16_t cs = crc0(md << 9); uint16_t cs = crc0(md << 9);
for (int i = 0; i < 16; ++i) for (int i = 0; i < 16; ++i)
CODE::set_be_bit(data, i+55, (cs>>i)&1); CODE::set_be_bit(data, i+55, (cs>>i)&1);
bchenc0(data, parity); bchenc(data, parity);
CODE::MLS seq4(mls1_poly); CODE::MLS seq4(mls1_poly);
value mls1_fac = std::sqrt(value(symbol_len) / value(mls1_len)); value mls1_fac = std::sqrt(value(symbol_len) / value(mls1_len));
for (int i = 0; i < symbol_len; ++i) for (int i = 0; i < symbol_len; ++i)
@ -171,62 +175,111 @@ struct Encoder
fdom[bin(i+mls1_off)] *= nrz(seq4()); fdom[bin(i+mls1_off)] *= nrz(seq4());
symbol(); symbol();
} }
cmplx mod_map(int8_t *b) void shorten()
{
int code_bits = 1 << code_order;
for (int i = 0, j = 0, k = 0; i < code_bits; ++i)
if ((frozen_bits[i/32] >> (i%32)) & 1 || k++ < crc_bits)
code[j++] = code[i];
}
cmplx mod_map(code_type *b)
{ {
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
case 3: case 7:
return PhaseShiftKeying<8, cmplx, int8_t>::map(b); case 10:
case 4: case 11:
case 5: return PhaseShiftKeying<8, cmplx, code_type>::map(b);
return PhaseShiftKeying<4, cmplx, int8_t>::map(b); case 8:
case 9:
case 12:
case 13:
return PhaseShiftKeying<4, cmplx, code_type>::map(b);
} }
return 0; return 0;
} }
void interleave() Encoder(DSP::WritePCM<value> *pcm, const uint8_t *inp, int freq_off, uint64_t call_sign, int oper_mode) :
{ pcm(pcm), crc0(0xA8F4), crc1(0xD419CC15), bchenc({
for (int i = 0; i < cons_cnt; ++i)
for (int k = 0; k < mod_bits; ++k)
bint[mod_bits*i+k] = code[cons_cnt*k+i];
}
Encoder(DSP::WritePCM<value> *pcm, uint8_t *inp, int freq_off, uint64_t call_sign, int oper_mode) :
pcm(pcm), crc0(0xA8F4), bchenc0({
0b100011101, 0b101110111, 0b111110011, 0b101101001, 0b100011101, 0b101110111, 0b111110011, 0b101101001,
0b110111101, 0b111100111, 0b100101011, 0b111010111, 0b110111101, 0b111100111, 0b100101011, 0b111010111,
0b000010011, 0b101100101, 0b110001011, 0b101100011, 0b000010011, 0b101100101, 0b110001011, 0b101100011,
0b100011011, 0b100111111, 0b110001101, 0b100101101, 0b100011011, 0b100111111, 0b110001101, 0b100101101,
0b101011111, 0b111111001, 0b111000011, 0b100111001, 0b101011111, 0b111111001, 0b111000011, 0b100111001,
0b110101001, 0b000011111, 0b110000111, 0b110110001}), bchenc1({ 0b110101001, 0b000011111, 0b110000111, 0b110110001}),
0b10000000000101101, 0b10000000101110011, 0b10000111110111101,
0b10101101001010101, 0b10001111100101111, 0b11111011110110101,
0b11010111101100101, 0b10111001101100111, 0b10000111010100001,
0b10111010110100111}),
oper_mode(oper_mode) oper_mode(oper_mode)
{ {
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
code_cols = 432; cons_cols = 432;
mod_bits = 3; mod_bits = 3;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break; break;
case 3: case 7:
code_cols = 400; cons_cols = 400;
mod_bits = 3; mod_bits = 3;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break; break;
case 4: case 8:
code_cols = 400; cons_cols = 400;
mod_bits = 2; mod_bits = 2;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break; break;
case 5: case 9:
code_cols = 360; cons_cols = 360;
mod_bits = 2; mod_bits = 2;
code_order = 16;
cons_bits = 64800;
mesg_bits = 43808;
frozen_bits = frozen_64800_43072;
break;
case 10:
cons_cols = 512;
mod_bits = 3;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break;
case 11:
cons_cols = 384;
mod_bits = 3;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break;
case 12:
cons_cols = 384;
mod_bits = 2;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break;
case 13:
cons_cols = 256;
mod_bits = 2;
code_order = 16;
cons_bits = 64512;
mesg_bits = 44096;
frozen_bits = frozen_64512_43072;
break; break;
default: default:
return; return;
} }
cons_cnt = ldpc_bits / mod_bits; cons_cnt = cons_bits / mod_bits;
code_rows = cons_cnt / code_cols; cons_rows = cons_cnt / cons_cols;
int offset = (freq_off * symbol_len) / rate; int offset = (freq_off * symbol_len) / rate;
code_off = offset - code_cols / 2; code_off = offset - cons_cols / 2;
mls0_off = offset - mls0_len + 1; mls0_off = offset - mls0_len + 1;
mls1_off = offset - mls1_len / 2; mls1_off = offset - mls1_len / 2;
papr_min = cmplx(1000, 1000), papr_max = cmplx(-1000, -1000); papr_min = cmplx(1000, 1000), papr_max = cmplx(-1000, -1000);
@ -234,15 +287,21 @@ struct Encoder
schmidl_cox(); schmidl_cox();
meta_data((call_sign << 8) | oper_mode); meta_data((call_sign << 8) | oper_mode);
pilot_block(); pilot_block();
bchenc1(inp, inp+data_bits/8, data_bits); for (int i = 0; i < data_bits; ++i)
for (int i = 0; i < bch_bits; ++i) mesg[i] = nrz(CODE::get_le_bit(inp, i));
code[i] = nrz(CODE::get_le_bit(inp, i)); crc1.reset();
ldpcenc(code, code + bch_bits); for (int i = 0; i < data_bits / 8; ++i)
interleave(); crc1(inp[i]);
for (int j = 0; j < code_rows; ++j) { for (int i = 0; i < 32; ++i)
for (int i = 0; i < code_cols; ++i) mesg[i+data_bits] = nrz((crc1()>>i)&1);
for (int i = crc_bits; i < mesg_bits; ++i)
mesg[i] = 1;
polarenc(code, mesg, frozen_bits, code_order);
shorten();
for (int j = 0; j < cons_rows; ++j) {
for (int i = 0; i < cons_cols; ++i)
fdom[bin(i+code_off)] *= fdom[bin(i+code_off)] *=
mod_map(bint+mod_bits*(code_cols*j+i)); mod_map(code+mod_bits*(cons_cols*j+i));
symbol(); symbol();
} }
schmidl_cox(); schmidl_cox();
@ -300,26 +359,36 @@ int main(int argc, char **argv)
return 1; return 1;
} }
int oper_mode = 2; int oper_mode = 6;
if (argc >= 9) if (argc >= 9)
oper_mode = std::atoi(argv[8]); oper_mode = std::atoi(argv[8]);
if (oper_mode < 2 || oper_mode > 5) { if (oper_mode < 6 || oper_mode > 13) {
std::cerr << "Unsupported operation mode." << std::endl; std::cerr << "Unsupported operation mode." << std::endl;
return 1; return 1;
} }
int band_width; int band_width;
switch (oper_mode) { switch (oper_mode) {
case 2: case 6:
band_width = 2700; band_width = 2700;
break; break;
case 3: case 7:
case 4: case 8:
band_width = 2500; band_width = 2500;
break; break;
case 5: case 9:
band_width = 2250; band_width = 2250;
break; break;
case 10:
band_width = 3200;
break;
case 11:
case 12:
band_width = 2400;
break;
case 13:
band_width = 1600;
break;
default: default:
return 1; return 1;
} }
@ -342,9 +411,8 @@ int main(int argc, char **argv)
std::cerr << "Couldn't open file \"" << input_name << "\" for reading." << std::endl; std::cerr << "Couldn't open file \"" << input_name << "\" for reading." << std::endl;
return 1; return 1;
} }
const int code_len = 64800 / 8; const int data_len = 43040 / 8;
const int data_len = code_len - (10 * 16 + 21600) / 8; uint8_t *input_data = new uint8_t[data_len];
uint8_t *input_data = new uint8_t[code_len];
for (int i = 0; i < data_len; ++i) for (int i = 0; i < data_len; ++i)
input_data[i] = input_file.get(); input_data[i] = input_file.get();
CODE::Xorshift32 scrambler; CODE::Xorshift32 scrambler;

39
freezer.cc Normal file
View file

@ -0,0 +1,39 @@
/*
Table generator for frozen bits
Copyright 2021 Ahmet Inan <inan@aicodix.de>
*/
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <functional>
#include "polar_freezer.hh"
template <int M>
void code(int N, int K)
{
long double erasure_probability = (long double)(N - K) / N;
double design_SNR = 10 * std::log10(-std::log(erasure_probability));
std::cerr << "design SNR: " << design_SNR << std::endl;
auto freeze = new CODE::PolarCodeConst0<M>;
double better_SNR = design_SNR + 1.59175;
std::cerr << "better SNR: " << better_SNR << std::endl;
long double better_probability = std::exp(-pow(10.0, better_SNR / 10));
auto frozen = new uint32_t[1<<(M-5)];
(*freeze)(frozen, M, K+(1<<M)-N, better_probability);
delete freeze;
std::cout << "static const uint32_t frozen_" << std::dec << N << "_" << K << "[" << (1<<(M-5)) << "] = { " << std::hex;
for (int i = 0; i < 1<<(M-5); ++i)
std::cout << "0x" << frozen[i] << ", ";
std::cout << "};" << std::endl;
}
int main()
{
code<16>(64512, 43040+32);
code<16>(64800, 43040+32);
return 0;
}

150
ldpc_tables.hh
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@ -1,150 +0,0 @@
/*
LDPC tables
Table entries below copied from:
https://www.etsi.org/deliver/etsi_en/302700_302799/302755/01.04.01_60/en_302755v010401p.pdf
Copyright 2018 Ahmet Inan <inan@aicodix.de>
*/
#pragma once
struct DVB_T2_TABLE_A3
{
static const int M = 360;
static const int N = 64800;
static const int K = 43200;
static const int LINKS_MIN_CN = 9;
static const int LINKS_MAX_CN = 10;
static const int LINKS_TOTAL = 215999;
static const int DEG_MAX = 13;
static constexpr int DEG[] = {
13, 3, 0
};
static constexpr int LEN[] = {
12, 108, 0
};
static constexpr int POS[] = {
317, 2255, 2324, 2723, 3538, 3576, 6194, 6700, 9101, 10057, 12739, 17407, 21039,
1958, 2007, 3294, 4394, 12762, 14505, 14593, 14692, 16522, 17737, 19245, 21272, 21379,
127, 860, 5001, 5633, 8644, 9282, 12690, 14644, 17553, 19511, 19681, 20954, 21002,
2514, 2822, 5781, 6297, 8063, 9469, 9551, 11407, 11837, 12985, 15710, 20236, 20393,
1565, 3106, 4659, 4926, 6495, 6872, 7343, 8720, 15785, 16434, 16727, 19884, 21325,
706, 3220, 8568, 10896, 12486, 13663, 16398, 16599, 19475, 19781, 20625, 20961, 21335,
4257, 10449, 12406, 14561, 16049, 16522, 17214, 18029, 18033, 18802, 19062, 19526, 20748,
412, 433, 558, 2614, 2978, 4157, 6584, 9320, 11683, 11819, 13024, 14486, 16860,
777, 5906, 7403, 8550, 8717, 8770, 11436, 12846, 13629, 14755, 15688, 16392, 16419,
4093, 5045, 6037, 7248, 8633, 9771, 10260, 10809, 11326, 12072, 17516, 19344, 19938,
2120, 2648, 3155, 3852, 6888, 12258, 14821, 15359, 16378, 16437, 17791, 20614, 21025,
1085, 2434, 5816, 7151, 8050, 9422, 10884, 12728, 15353, 17733, 18140, 18729, 20920,
856, 1690, 12787,
6532, 7357, 9151,
4210, 16615, 18152,
11494, 14036, 17470,
2474, 10291, 10323,
1778, 6973, 10739,
4347, 9570, 18748,
2189, 11942, 20666,
3868, 7526, 17706,
8780, 14796, 18268,
160, 16232, 17399,
1285, 2003, 18922,
4658, 17331, 20361,
2765, 4862, 5875,
4565, 5521, 8759,
3484, 7305, 15829,
5024, 17730, 17879,
7031, 12346, 15024,
179, 6365, 11352,
2490, 3143, 5098,
2643, 3101, 21259,
4315, 4724, 13130,
594, 17365, 18322,
5983, 8597, 9627,
10837, 15102, 20876,
10448, 20418, 21478,
3848, 12029, 15228,
708, 5652, 13146,
5998, 7534, 16117,
2098, 13201, 18317,
9186, 14548, 17776,
5246, 10398, 18597,
3083, 4944, 21021,
13726, 18495, 19921,
6736, 10811, 17545,
10084, 12411, 14432,
1064, 13555, 17033,
679, 9878, 13547,
3422, 9910, 20194,
3640, 3701, 10046,
5862, 10134, 11498,
5923, 9580, 15060,
1073, 3012, 16427,
5527, 20113, 20883,
7058, 12924, 15151,
9764, 12230, 17375,
772, 7711, 12723,
555, 13816, 15376,
10574, 11268, 17932,
15442, 17266, 20482,
390, 3371, 8781,
10512, 12216, 17180,
4309, 14068, 15783,
3971, 11673, 20009,
9259, 14270, 17199,
2947, 5852, 20101,
3965, 9722, 15363,
1429, 5689, 16771,
6101, 6849, 12781,
3676, 9347, 18761,
350, 11659, 18342,
5961, 14803, 16123,
2113, 9163, 13443,
2155, 9808, 12885,
2861, 7988, 11031,
7309, 9220, 20745,
6834, 8742, 11977,
2133, 12908, 14704,
10170, 13809, 18153,
13464, 14787, 14975,
799, 1107, 3789,
3571, 8176, 10165,
5433, 13446, 15481,
3351, 6767, 12840,
8950, 8974, 11650,
1430, 4250, 21332,
6283, 10628, 15050,
8632, 14404, 16916,
6509, 10702, 16278,
15900, 16395, 17995,
8031, 18420, 19733,
3747, 4634, 17087,
4453, 6297, 16262,
2792, 3513, 17031,
14846, 20893, 21563,
17220, 20436, 21337,
275, 4107, 10497,
3536, 7520, 10027,
14089, 14943, 19455,
1965, 3931, 21104,
2439, 11565, 17932,
154, 15279, 21414,
10017, 11269, 16546,
7169, 10161, 16928,
10284, 16791, 20655,
36, 3175, 8475,
2605, 16269, 19290,
8947, 9178, 15420,
5687, 9156, 12408,
8096, 9738, 14711,
4935, 8093, 19266,
2667, 10062, 15972,
6389, 11318, 14417,
8800, 18137, 18434,
5824, 5927, 15314,
6056, 13168, 15179,
3284, 13138, 18919,
13115, 17259, 17332,
};
};

2
polar_tables.hh Normal file
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