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do pts on even and odd subcarrier sets

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This commit is contained in:
Ahmet Inan 2025-08-07 00:50:10 +02:00
commit 64f01501cc
2 changed files with 50 additions and 26 deletions
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29
decode.cc
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@ -296,18 +296,31 @@ struct Decoder : Common
tone[i] *= nrz(seq1());
for (int i = 0; i < tone_count; ++i)
demod[i] = demod_or_erase(tone[i], chan[i]);
value pilot_sum = 0;
for (int i = 0; i < pilot_tones; ++i)
pilot_sum += demod[i*block_length+pilot_off].real();
int pilot_phase = DSP::signum(pilot_sum);
if (std::abs(pilot_sum) < pilot_tones / 4) {
value ptsa_sum = 0;
for (int i = 0; i < pilot_tones; i += 2)
ptsa_sum += demod[i*block_length+pilot_off].real();
int ptsa_phase = DSP::signum(ptsa_sum);
if (std::abs(ptsa_sum) < pilot_tones / 4) {
std::cerr << "pilot phase damaged" << std::endl;
oper_mode = -1;
break;
}
for (int i = 0; i < tone_count; ++i) {
tone[i] *= pilot_phase;
demod[i] *= pilot_phase;
for (int i = 0; i < tone_count; i += 2) {
tone[i] *= ptsa_phase;
demod[i] *= ptsa_phase;
}
value ptsb_sum = 0;
for (int i = 1; i < pilot_tones; i += 2)
ptsb_sum += demod[i*block_length+pilot_off].real();
int ptsb_phase = DSP::signum(ptsb_sum);
if (std::abs(ptsb_sum) < pilot_tones / 4) {
std::cerr << "pilot phase damaged" << std::endl;
oper_mode = -1;
break;
}
for (int i = 1; i < tone_count; i += 2) {
tone[i] *= ptsb_phase;
demod[i] *= ptsb_phase;
}
for (int i = 0; i < pilot_tones; ++i) {
index[i] = tone_off + block_length * i + pilot_off;

47
encode.cc
View file

@ -39,6 +39,8 @@ struct Encoder : public Common
cmplx fdom[symbol_len];
cmplx tdom[symbol_len];
cmplx temp[symbol_len];
cmplx ptsa[symbol_len];
cmplx ptsb[symbol_len];
cmplx best[symbol_len];
cmplx kern[symbol_len];
cmplx guard[guard_len];
@ -90,29 +92,38 @@ struct Encoder : public Common
} else {
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 0; i < tone_count; ++i)
for (int i = 0; i < tone_count; i += 2)
fdom[bin(i+tone_off)] = tone[i];
bwd(temp, fdom);
bwd(ptsa, fdom);
for (int i = 0; i < symbol_len; ++i)
temp[i] *= scale;
ptsa[i] *= scale;
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 1; i < tone_count; i += 2)
fdom[bin(i+tone_off)] = tone[i];
bwd(ptsb, fdom);
for (int i = 0; i < symbol_len; ++i)
ptsb[i] *= scale;
value best_papr = 1000;
for (value pilot_phase = -1; pilot_phase < 2; pilot_phase += 2) {
for (value ptsa_phase = -1; ptsa_phase < 2; ptsa_phase += 2) {
for (int i = 0; i < symbol_len; ++i)
tdom[i] = pilot_phase * temp[i];
value peak = 0, mean = 0;
for (int i = 0; i < symbol_len; ++i) {
value power(norm(tdom[i]));
peak = std::max(peak, power);
mean += power;
}
mean /= symbol_len;
value cand_papr(peak / mean);
if (cand_papr < best_papr) {
best_papr = cand_papr;
temp[i] = ptsa_phase * ptsa[i];
for (value ptsb_phase = -1; ptsb_phase < 2; ptsb_phase += 2) {
for (int i = 0; i < symbol_len; ++i)
best[i] = tdom[i];
if (cand_papr < 5)
break;
tdom[i] = ptsb_phase * ptsb[i] + temp[i];
value peak = 0, mean = 0;
for (int i = 0; i < symbol_len; ++i) {
value power(norm(tdom[i]));
peak = std::max(peak, power);
mean += power;
}
mean /= symbol_len;
value cand_papr(peak / mean);
if (cand_papr < best_papr) {
best_papr = cand_papr;
for (int i = 0; i < symbol_len; ++i)
best[i] = tdom[i];
}
}
}
for (int i = 0; i < symbol_len; ++i)