Mirror/aicodix___modem
1
0
Fork 0
mirror of https://github.com/aicodix/modem.git synced 2026-04-28 09:43:10 +00:00
Code Issues Projects Releases Packages Wiki Activity

limit clipping while testing and unlimited when done

Browse source
This commit is contained in:
Ahmet Inan 2025-07-11 06:41:34 +02:00
commit 51f49f56e2
1 changed files with 18 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

30
encode.cc
View file

@ -48,7 +48,7 @@ struct Encoder : public Common
{
return 1 - 2 * bit;
}
void clipping_and_filtering(value scale)
void clipping_and_filtering(value scale, bool limit)
{
for (int i = 0; i < symbol_len; ++i) {
value pwr = norm(tdom[i]);
@ -58,12 +58,18 @@ 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
} 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)
@ -71,6 +77,7 @@ struct Encoder : public Common
}
void symbol(int symbol_number)
{
value scale = value(0.5) / std::sqrt(value(tone_count));
for (int i = 0; differential && symbol_number > 0 && i < tone_count; ++i)
tone[i] *= temp[i];
int trials = symbol_number ? 128 : 4;
@ -92,17 +99,11 @@ struct Encoder : public Common
for (int i = 0; i < tone_count; ++i)
fdom[bin(i+tone_off)] = temp[i];
bwd(tdom, fdom);
value scale = value(0.5) / std::sqrt(value(tone_count));
for (int i = 0; i < symbol_len; ++i)
tdom[i] *= scale;
bool papr_reduction = symbol_number >= 0;
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()));
if (!papr_reduction)
if (symbol_number < 0)
break;
clipping_and_filtering(scale, true);
value peak = 0, mean = 0;
for (int i = 0; i < symbol_len; ++i) {
value power(norm(tdom[i]));
@ -116,6 +117,11 @@ struct Encoder : public Common
break;
}
}
if (symbol_number >= 0)
clipping_and_filtering(scale, false);
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()));
if (symbol_number != -1) {
for (int i = 0; i < guard_len; ++i)
guard[i] = DSP::lerp(guard[i], tdom[i+symbol_len-guard_len], weight[i]);