Graham McIntire 82bf248ab7 Phase 4: Ray-traced duct geometry ... Duct module (Propagation.Duct): - refractivity_profile/1: ITU-R P.453 N at each native level - m_profile/1: modified refractivity M = N + 157*h(km) - detect_ducts/1: find contiguous regions where dM/dh < 0, returning base/top height, thickness, and M-deficit per duct - min_trapped_frequency_ghz/1: waveguide approximation (Bean & Dutton) for the minimum frequency a duct of given geometry can trap - analyze/1: full pipeline from native profile to duct list + best trapped frequency across all ducts Derive task updated to also compute ducts JSONB and best_duct_band_ghz alongside the Phase 2 turbulence fields. Backtest features: duct_thickness, best_duct_freq, duct_usable_10ghz, duct_usable_24ghz, duct_usable_47ghz. Real-data validation: 2022-08-20 12Z TX profile shows 0 ducts (M increases monotonically) — correct for a well-mixed boundary layer on a turbulent August afternoon (Ri=0.16).		2026-04-10 08:31:16 -05:00
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tasks	Phase 4: Ray-traced duct geometry	2026-04-10 08:31:16 -05:00