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average both synchronization symbols for a better channel estimate

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This commit is contained in:
Ahmet Inan 2025-07-06 12:58:58 +02:00
commit 0ce4068061
1 changed files with 16 additions and 0 deletions
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decode.cc
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@ -163,6 +163,11 @@ struct Decoder : Common
std::cerr << "coarse cfo: " << cfo_rad * (rate / Const::TwoPi()) << " Hz " << std::endl;
osc.omega(-cfo_rad);
for (int i = 0; i < symbol_len; ++i)
tdom[i] = buf[i+symbol_pos] * osc();
fwd(fdom, tdom);
for (int i = 0; i < tone_count; ++i)
chan[i] = fdom[bin(i+tone_off)];
for (int i = 0; i < symbol_len; ++i)
tdom[i] = buf[i+symbol_pos+symbol_len] * osc();
for (int i = 0; i < guard_len; ++i)
@ -170,6 +175,17 @@ struct Decoder : Common
fwd(fdom, tdom);
for (int i = 0; i < tone_count; ++i)
tone[i] = fdom[bin(i+tone_off)];
for (int i = 0; i < tone_count; ++i) {
index[i] = tone_off + i;
phase[i] = arg(demod_or_erase(tone[i], chan[i]));
}
tse.compute(index, phase, tone_count);
//std::cerr << "Theil-Sen slope = " << tse.slope() << std::endl;
//std::cerr << "Theil-Sen yint = " << tse.yint() << std::endl;
for (int i = 0; i < tone_count; ++i)
chan[i] *= DSP::polar<value>(1, tse(i+tone_off));
for (int i = pilot_off; i < tone_count; i += block_length)
chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
CODE::MLS seq0(mls0_poly, mls0_seed);
for (int i = 0; i < tone_count; ++i)
chan[i] = nrz(seq0()) * tone[i];