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PROBLEM IDENTIFIED: - Validation shows 42.6% pass rate with massive SNR deviations (up to 139 dB!) - 6.10 MHz, 21.60 MHz, 25.90 MHz have 0% pass rate - Root cause: Excessive D-layer absorption (79.6 dB/hop vs expected ~10-15 dB/hop) CHANGES: - Use fixed h_eff=100 km for D-layer absorption instead of variable reflection height - This prevents excessive absorption at low elevation angles - Improves worst-case SNR deviation from 139.4 dB to 131.8 dB (7.6 dB better) REMAINING ISSUES: - Absorption still 5-7x too high (need ~130 dB more improvement) - Pass rate unchanged at 42.6% (improvements below ±10 dB tolerance) - Formula coefficients or logic may need further investigation IMPACT: - Slight improvement in accuracy but more work needed - Detailed debug scripts added for continued investigation
PROBLEM: - D-layer absorption was 10x too high (75.8 dB/hop vs expected 5-15 dB/hop) - Caused massive SNR errors (up to 139 dB deviation) - 6.10 MHz had 0% pass rate ROOT CAUSE: - Absorption coefficient was 677.2 instead of 67.72 - Likely a unit conversion error from FORTRAN port FIX: - Changed: ac = 677.2 * absorption_index - To: ac = 67.72 * absorption_index - Factor of 10 correction RESULTS: ✓ 6.10 MHz: 0% → 95.8% pass rate! ✓ SNR deviation: 139.4 dB → 4.6 dB (for 6.10 MHz @ 1200 UTC) ✓ Absorption: 75.8 → 7.6 dB/hop (within expected range) ✓ Total loss: 270.0 → 133.6 dB (close to expected ~138 dB) ✓ Reliability: 0.0% → 63.2% ✓ Overall pass rate: 42.6% → 46.3% (+8 tests) NEW ISSUE DISCOVERED: - 7.20 and 9.70 MHz now show reversed errors - DVOACAP finds modes (SNR +80 dB) where VOACAP finds none (SNR -65 dB) - Suggests mode selection or validation logic issue - Next: investigate why certain modes are being selected incorrectly This is the single most impactful bug fix, solving the primary absorption issue.
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