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reject phases too close to diagonals

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This commit is contained in:
Ahmet Inan 2025-08-08 07:54:53 +02:00
commit f9c29575b5
1 changed files with 6 additions and 2 deletions
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8
decode.cc
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@ -229,12 +229,16 @@ struct Decoder : Common
for (int i = offset; i < tone_count; i += stride)
if (i % block_length == pilot_off)
sum += demod[i];
if (abs(sum) < pilot_tones / (2 * stride)) {
value half = pilot_tones / (2 * stride);
value magr = std::abs(sum.real());
value magi = std::abs(sum.imag());
bool real = magr > magi;
if (real ? (magr < half || 2 * magi > magr) : (magi < half || 2 * magr > magi)) {
std::cerr << "pilot phase damaged" << std::endl;
oper_mode = -1;
return false;
}
cmplx rot = std::abs(sum.real()) < std::abs(sum.imag()) ? cmplx(0, sum.imag() < 0 ? 1 : -1) : cmplx(sum.real() < 0 ? -1 : 1);
cmplx rot = real ? cmplx(sum.real() < 0 ? -1 : 1) : cmplx(0, sum.imag() < 0 ? 1 : -1);
for (int i = offset; i < tone_count; i += stride) {
tone[i] *= rot;
demod[i] *= rot;