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use a simpler estimation for finer CFO

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This commit is contained in:
Ahmet Inan 2021-07-20 21:47:49 +02:00
commit 357a90805c
1 changed files with 3 additions and 17 deletions
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20
decode.cc
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@ -195,7 +195,6 @@ struct Decoder
uint16_t erasures[24];
cmplx head[symbol_len], tail[symbol_len], cons[cons_max];
cmplx fdom[symbol_len], tdom[buffer_len], resam[buffer_len];
value phase[symbol_len/2];
value cfo_rad, sfo_rad;
int symbol_pos;
int oper_mode;
@ -236,23 +235,10 @@ struct Decoder
}
value frac_cfo(const cmplx *samples)
{
value avg = 0;
cmplx sum;
for (int i = 0; i < symbol_len/2; ++i)
avg += phase[i] = arg(samples[i] * conj(samples[i+symbol_len/2]));
avg /= value(symbol_len/2);
value var = 0;
for (int i = 0; i < symbol_len/2; ++i)
var += (phase[i] - avg) * (phase[i] - avg);
value std_dev = std::sqrt(var/(symbol_len/2-1));
int count = 0;
value sum = 0;
for (int i = 0; i < symbol_len/2; ++i) {
if (std::abs(phase[i] - avg) <= std_dev) {
sum += phase[i];
++count;
}
}
return sum / (count * symbol_len/2);
sum += samples[i] * conj(samples[i+symbol_len/2]);
return arg(sum) / (symbol_len/2);
}
void deinterleave()
{