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FT8 demod: fix duplicated code (1)

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f4exb
2026-03-13 18:37:09 +01:00
parent 71d6208fe9
commit 81f7d2ff99
4 changed files with 104 additions and 331 deletions
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ft8/ft8.cpp
+67 -64
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@@ -47,6 +47,71 @@
namespace FT8 {
namespace {
template<typename ParamsT>
float bayesImpl(
const double apriori174[],
ParamsT& params,
float best_zero,
float best_one,
int lli,
Stats &bests,
Stats &all
)
{
float maxlog = 4.97;
float ll = 0;
float pzero = 0.5;
float pone = 0.5;
if (params.use_apriori)
{
pzero = 1.0 - apriori174[lli];
pone = apriori174[lli];
}
// zero
float a = pzero * bests.problt(best_zero) * (1.0 - all.problt(best_one));
if (params.bayes_how == 1) {
a *= all.problt(all.mean() + (best_zero - best_one));
}
// one
float b = pone * bests.problt(best_one) * (1.0 - all.problt(best_zero));
if (params.bayes_how == 1) {
b *= all.problt(all.mean() + (best_one - best_zero));
}
float p;
if (a + b == 0) {
p = 0.5;
} else {
p = a / (a + b);
}
if (1 - p == 0.0) {
ll = maxlog;
} else {
ll = log(p / (1 - p));
}
if (ll > maxlog) {
ll = maxlog;
}
if (ll < -maxlog) {
ll = -maxlog;
}
return ll;
}
} // namespace
// a-priori probability of each of the 174 LDPC codeword
// bits being one. measured from reconstructed correct
// codewords, into ft8bits, then python bprob.py.
@@ -1675,72 +1740,10 @@ float FT8::bayes(
Stats &all
)
{
float maxlog = 4.97;
float ll = 0;
float pzero = 0.5;
float pone = 0.5;
if (params.use_apriori)
{
pzero = 1.0 - apriori174[lli];
pone = apriori174[lli];
}
//
// Bayes combining rule normalization from:
// http://cs.wellesley.edu/~anderson/writing/naive-bayes.pdf
//
// a = P(zero)P(e0|zero)P(e1|zero)
// b = P(one)P(e0|one)P(e1|one)
// p = a / (a + b)
//
// also see Mark Owen's book Practical Signal Processing,
// Chapter 6.
//
// zero
float a = pzero * bests.problt(best_zero) * (1.0 - all.problt(best_one));
// printf("FT8::bayes: a: %f bp: %f ap: %f \n", a, bests.problt(best_zero), all.problt(best_one));
if (params.bayes_how == 1) {
a *= all.problt(all.mean() + (best_zero - best_one));
}
// one
float b = pone * bests.problt(best_one) * (1.0 - all.problt(best_zero));
// printf("FT8::bayes: b: %f bp: %f ap: %f \n", b, bests.problt(best_one), all.problt(best_zero));
if (params.bayes_how == 1) {
b *= all.problt(all.mean() + (best_one - best_zero));
}
float p;
if (a + b == 0) {
p = 0.5;
} else {
p = a / (a + b);
}
// printf("FT8::bayes: all.mean: %f a: %f b: %f p: %f\n", all.mean(), a, b, p);
if (1 - p == 0.0) {
ll = maxlog;
} else {
ll = log(p / (1 - p));
}
if (ll > maxlog) {
ll = maxlog;
}
if (ll < -maxlog) {
ll = -maxlog;
}
return ll;
return bayesImpl(apriori174, params, best_zero, best_one, lli, bests, all);
}
//
// c79 is 79x8 complex tones, before un-gray-coding.
//