assets: 20m real-HF noise bed for OTASim noise-overlay (task #71)#34
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Reference 10-minute capture of 20m band noise at 14.100 MHz (~11:30 AST 2026-05-18). Captured via Yaesu FT-891 USB data out through ultra_gui's -rec path, packaged as 16-bit mono 48 kHz WAV. Recording stats: - Duration: 600.00 s (10:00 exactly) - RMS: 0.0363, peak: 0.4738, no clipping - Per-5s segment RMS stddev: 0.003 (very stable, no dominant spikes) - 98% of energy in 300-3000 Hz SSB passband - 55 MB binary Content character: - Steady real-HF broadband noise (structured, not Gaussian) - NCDXF beacon rotation interleaved (~60+ beacon hits over 10 min) - No dominant local QSO Intended use: - Task #71 (OTASim noise-overlay feature) loads this as the noise source instead of AWGN. Normalize to unit RMS at load time, scale per tick by kModemReferenceRms * 10^(-snr_db/20) (same formula as the AWGN model in src/ota_channel_core/models.cpp), and mix into each receiver's outbox. - ota_simulator v2 real-HF noise overlay path can already overlay this on synthetic transmissions today (see commit 88a2acb). - Smaller test fixtures for tests/fixtures/ can be extracted later. Adds: - recordings/ota_noise_bed_2026-05-18_20m_14100/noise_bed.wav - recordings/ota_noise_bed_2026-05-18_20m_14100/README.md (provenance, levels, spectral profile, usage notes) - .gitignore: new exception !recordings/ota_noise_bed_*/ so future noise beds can be committed alongside existing OTA capture directories. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Reference 10-minute capture of 20m band noise at 14.100 MHz, captured
this morning via Yaesu FT-891 USB data out → `ultra_gui -rec`. Drops
into the gitignore-already-permitted `recordings/` directory pattern
(new exception added for `ota_noise_bed_*`).
Real-HF content: broadband structured noise + NCDXF beacon rotation
(~60+ beacons interleaved over 10 min) + no dominant local QSO.
Why
OTASim today only has AWGN + Watterson channel models — synthetic noise
that doesn't represent real HF character. Task #71 ("noise bed feature
using diagnostic bundle WAV") will load a recording like this as the
noise source instead of AWGN, scaled by the same SNR formula.
This asset unblocks #71 — there's now real data committed to the
repo that can be wired in.
Changes
provenance / levels / usage notes
noise beds (different bands, different conditions) can be committed
alongside.
Test plan
Asset-only commit. No code, no tests.
🤖 Generated with Claude Code