Mirror/aicodix___modem
1
0
Fork 0
mirror of https://github.com/aicodix/modem.git synced 2026-04-27 22:35:41 +00:00
Code Issues Projects Releases Packages Wiki Activity

replaced reserved tones with pilot tones

Browse source
This commit is contained in:
Ahmet Inan 2025-07-10 17:45:07 +02:00
commit 04beed4a4c
3 changed files with 16 additions and 61 deletions
Download patch file Download diff file Expand all files Collapse all files

14
common.hh
View file

@ -18,18 +18,16 @@ struct Common
static const int data_max = 4096;
static const int mls0_poly = 0x331;
static const int mls0_seed = 214;
static const int mls1_poly = 0x25;
static const int mls1_poly = 0x43;
static const int data_tones = 256;
static const int pilot_tones = 32;
static const int reserved_tones = 32;
static const int tone_count = data_tones + pilot_tones + reserved_tones;
static const int block_length = 10;
static const int pilot_tones = 64;
static const int tone_count = data_tones + pilot_tones;
static const int block_length = 5;
static const int block_skew = 3;
static const int first_pilot = 4;
static const int first_reserved = 9;
CODE::CRC<uint32_t> crc0;
CODE::HadamardEncoder<6> hadamard_encoder;
int8_t meta[32];
CODE::HadamardEncoder<7> hadamard_encoder;
int8_t meta[64];
uint8_t data[data_max];
const uint32_t *frozen_bits;
int mod_bits;

12
decode.cc
View file

@ -49,7 +49,7 @@ struct Decoder : Common
DSP::BipBuffer<cmplx, buffer_len> input_hist;
DSP::TheilSenEstimator<value, tone_count> tse;
SchmidlCox<value, cmplx, search_pos, symbol_len, guard_len> correlator;
CODE::HadamardDecoder<6> hadamard_decoder;
CODE::HadamardDecoder<7> hadamard_decoder;
CODE::PolarListDecoder<mesg_type, code_max> polar_decoder;
mesg_type mesg[bits_max];
code_type code[bits_max], perm[bits_max];
@ -251,7 +251,6 @@ struct Decoder : Common
std::cerr << "Es/N0 (dB):";
for (int j = 0, k = 0; j < symbol_count; ++j) {
pilot_off = (block_skew * j + first_pilot) % block_length;
reserved_off = (block_skew * j + first_reserved) % block_length;
if (j) {
for (int i = 0; i < extended_len; ++i)
correlator(buf = next_sample());
@ -294,20 +293,17 @@ struct Decoder : Common
chan[i] *= DSP::polar<value>(1, tse(i+tone_off));
if (differential) {
for (int i = 0; i < tone_count; ++i)
if (i % block_length != reserved_off)
chan[i] = fdom[bin(i+tone_off)];
chan[i] = fdom[bin(i+tone_off)];
} else {
for (int i = pilot_off; i < tone_count; i += block_length)
chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
}
CODE::MLS seq(0x163, meta_data);
for (int i = 0; i < tone_count; ++i)
if (i % block_length != pilot_off && i % block_length != reserved_off)
if (i % block_length != pilot_off)
demod[i] *= nrz(seq());
value sp = 0, np = 0;
for (int i = 0, l = k; i < tone_count; ++i) {
if (i % block_length == reserved_off)
continue;
cmplx hard(1, 0);
if (i % block_length != pilot_off) {
int bits = mod_bits;
@ -329,8 +325,6 @@ struct Decoder : Common
for (int i = 0; i < tone_count; ++i) {
if (i % block_length == pilot_off)
continue;
if (i % block_length == reserved_off)
continue;
int bits = mod_bits;
if (oper_mode >= 7 && oper_mode <= 9 && k % 32 == 30)
bits = 2;

51
encode.cc
View file

@ -48,7 +48,7 @@ struct Encoder : public Common
{
return 1 - 2 * bit;
}
void clipping_and_filtering(value scale, bool limit)
void clipping_and_filtering(value scale)
{
for (int i = 0; i < symbol_len; ++i) {
value pwr = norm(tdom[i]);
@ -58,39 +58,17 @@ struct Encoder : public Common
fwd(fdom, tdom);
for (int i = 0; i < symbol_len; ++i) {
int j = bin(i + tone_off);
if (i >= tone_count) {
if (i >= tone_count)
fdom[j] = 0;
} else if (i % block_length == pilot_off) {
else if (i % block_length == pilot_off)
fdom[j] = temp[i];
} else if (i % block_length == reserved_off) {
fdom[j] = 0;
} else {
else
fdom[j] *= 1 / (scale * symbol_len);
cmplx err = fdom[j] - temp[i];
value mag = abs(err);
value lim = 0.5 * mod_distance();
if (limit && mag > lim)
fdom[j] -= ((mag - lim) / mag) * err;
}
}
bwd(tdom, fdom);
for (int i = 0; i < symbol_len; ++i)
tdom[i] *= scale;
}
void tone_reservation()
{
for (int n = 0; n < 10; ++n) {
int peak = 0;
for (int i = 1; i < symbol_len; ++i)
if (norm(tdom[peak]) < norm(tdom[i]))
peak = i;
cmplx orig = tdom[peak];
if (norm(orig) <= value(1))
break;
for (int i = 0; i < symbol_len; ++i)
tdom[i] -= orig * kern[bin(i-peak)];
}
}
void symbol(int symbol_number)
{
for (int i = 0; differential && symbol_number > 0 && i < tone_count; ++i)
@ -105,7 +83,7 @@ struct Encoder : public Common
for (int i = 0, m = 0; i < tone_count; ++i)
if (i % block_length == pilot_off)
temp[i] *= meta[m++];
else if (i % block_length != reserved_off)
else
temp[i] *= nrz(seq());
}
for (int i = 0; i < symbol_len; ++i)
@ -117,10 +95,8 @@ struct Encoder : public Common
for (int i = 0; i < symbol_len; ++i)
tdom[i] *= scale;
bool papr_reduction = symbol_number >= 0;
if (papr_reduction) {
clipping_and_filtering(scale, true);
tone_reservation();
}
if (papr_reduction)
clipping_and_filtering(scale);
auto clamp = [](value v){ return v < value(-1) ? value(-1) : v > value(1) ? value(1) : v; };
for (int i = 0; i < symbol_len; ++i)
tdom[i] = cmplx(clamp(tdom[i].real()), clamp(tdom[i].imag()));
@ -243,15 +219,6 @@ struct Encoder : public Common
dest[i] = src[seq()];
}
}
void tone_reservation_kernel()
{
value mag(0.001);
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 0; i < reserved_tones; ++i)
fdom[bin(i*block_length+tone_off+reserved_off)] = mag;
bwd(kern, fdom);
}
void guard_interval_weights()
{
for (int i = 0; i < guard_len / 4; ++i)
@ -298,12 +265,9 @@ struct Encoder : public Common
std::cerr << "PAPR (dB):";
for (int j = 0, k = 0; j < symbol_count; ++j) {
pilot_off = (block_skew * j + first_pilot) % block_length;
reserved_off = (block_skew * j + first_reserved) % block_length;
for (int i = 0; i < tone_count; ++i) {
if (i % block_length == pilot_off) {
tone[i] = nrz(seq1());
} else if (i % block_length == reserved_off) {
tone[i] = 0;
} else {
int bits = mod_bits;
if (oper_mode >= 7 && oper_mode <= 9 && k % 32 == 30)
@ -314,7 +278,6 @@ struct Encoder : public Common
k += bits;
}
}
tone_reservation_kernel();
symbol(j);
}
std::cerr << std::endl;