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FT4 decoder: nearly all decode OK

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f4exb 2026-03-08 02:08:57 +01:00
parent fbfa04a06d
commit 2e0801e57b
3 changed files with 664 additions and 516 deletions
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1162
ft8/ft4.cpp
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File diff suppressed because it is too large Load Diff

16
ft8/ft4.h
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@ -511,9 +511,9 @@ private:
int one_iter(const std::vector<float> &samples200, int best_off, float hz_for_cb);
//
// estimate SNR, yielding numbers vaguely similar to WSJT-X.
// m79 is a 79x8 complex FFT output.
// m103 is a 103x4 complex FFT output.
//
float guess_snr(const FFTEngine::ffts_t &m79);
float guess_snr(const FFTEngine::ffts_t &m103);
//
// compare phases of successive symbols to guess whether
// the starting offset is a little too high or low.
@ -525,7 +525,7 @@ private:
// a phase that depends on the symbol's frequency;
// a particular offset error causes a phase error
// that depends on frequency.
// hz0 is actual FFT bin number of m79[...][0] (always 4).
// hz0 is actual FFT bin number of m103[...][0].
//
// the output adj_hz is relative to the FFT bin center;
// a positive number means the real signal seems to be
@ -534,16 +534,16 @@ private:
// adj_off is the amount to change the offset, in samples.
// should be subtracted from offset.
//
void fine(const FFTEngine::ffts_t &m79, int, float &adj_hz, float &adj_off);
void fine(const FFTEngine::ffts_t &m103, int, float &adj_hz, float &adj_off);
//
// subtract a corrected decoded signal from nsamples_,
// perhaps revealing a weaker signal underneath,
// to be decoded in a subsequent pass.
//
// re79[] holds the error-corrected symbol numbers.
// re103[] holds the error-corrected symbol numbers.
//
void subtract(
const std::vector<int> re79,
const std::vector<int> re103,
float hz0,
float hz1,
float off_sec
@ -565,7 +565,7 @@ private:
float,
int use_osd,
const char *comment1,
const FFTEngine::ffts_t &m79
const FFTEngine::ffts_t &m103
);
//
// given 174 bits corrected by LDPC, work
@ -576,7 +576,7 @@ private:
//
std::vector<int> recode(int a174[]);
//
// the signal is at roughly 25 hz in samples200.
// the signal is centered around 46.8 Hz in samples200.
//
// return 2 if it decodes to a brand-new message.
// return 1 if it decodes but we've already seen it,

2
sdrbench/test_ft4.cpp
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@ -216,7 +216,7 @@ void MainBench::testFT4(const QString& wavFile, const QString& argsStr)
wfile.close();
FT8::FT4DecoderLight decoder;
FT8::FT4Decoder decoder;
decoder.getParams().nthreads = nthreads;
decoder.getParams().use_osd = 1;
decoder.getParams().osd_depth = 6;