The WSPR decoder was producing many false positive decodes due to
several overly permissive thresholds that allowed noise to reach the
Fano sequential decoder, which could then converge on random data:
- Raise normalized sync score threshold from 0.10 to 0.20 to reject
noise candidates before attempting expensive Fano decoding
- Add minimum SNR gate (-20 dB) to skip candidates where the signal
is indistinguishable from noise
- Return and check the Fano decoder's cumulative path metric, rejecting
low-confidence decodes (metric < 20) that are likely noise artifacts
- Raise RMS threshold from 0.0005 to 0.005 to reject near-silent audio
- Add near-frequency deduplication to prevent the same signal decoded
at slightly different (freq, dt) offsets from appearing multiple times
- Add noise-only regression test to verify no false positives on random
input
https://claude.ai/code/session_01HTBoEsD1hp99TiYMSaHMVG
Signed-off-by: Claude <noreply@anthropic.com>
Claude
54b1f20ea4