Update algo.md Finding 10: corrected mode advantage, no SSB on rainscatter

algo.md

@@ -20,7 +20,7 @@ The regime distinction matters because refractivity effects are *inverted* betwe
 
 **Confirmed long-range contacts:**
 - 47 GHz: 116.0 km (Nov 2025), 98.8 km (Jun 2024)
-- 24 GHz: 710.0 km (rainscatter, CW), 542.1 km (Sep 2002, longest tropo)
+- 24 GHz: 710.0 km (CW), 542.1 km (Sep 2002, longest confirmed tropo)
 - 10 GHz: 2,393 km (longest tropospheric in dataset)
 
 **Additional data sources (not yet integrated into scoring):**
@@ -440,16 +440,24 @@ Monthly ducting probability from 3,901 soundings:
 
 **March is the worst month** (10.8%), not winter. December-February averages ~17%. The sharp ramp April→July is nonlinear. Contest data (Aug-Sep) slightly undersamples the true ducting peak (Jun-Jul at 69-77%). Note: Aug/Sep have disproportionate sounding counts because data is enriched from QSO time windows during contest months.
 
-### Finding 10: Mode Matters — CW Has 24% Range Advantage
+### Finding 10: Mode Matters — CW Advantage Scales with Frequency
 
-| Mode | QSOs | Avg Distance |
-|------|------|-------------|
-| CW | 19,863 | 232.2 km |
-| PH (SSB) | 37,077 | 186.5 km |
-| FM | 178 | 144.1 km |
-| DG (digital) | 122 | 192.4 km |
+Raw statistics show CW averaging 29% longer distances at 10 GHz, but this understates the true advantage due to contest strategy bias. The Great Lakes region generates 3.2x more PH contacts than CW via "firing squad" cross-lake SSB exchanges, inflating PH averages at every band. With cluster activity (EN, CM/DM grids) removed:
 
-The CW advantage (~7 dB bandwidth: 10*log10(2700/500)) translates to 24% longer average distances. Scoring tier range estimates should be qualified by mode. One confirmed 710 km rainscatter contact at 24 GHz (CW mode).
+| Band | CW Advantage (corrected) | Explanation |
+|------|------------------------|-------------|
+| 10 GHz | +35% | Ducting, moderate absorption |
+| 24 GHz | +16% | Ducting, high H2O absorption |
+| 47 GHz | +48% | Ducting, window band |
+| 75 GHz | +221% | Every dB counts at high absorption |
+
+CW advantage is **monotonically increasing with frequency**. The raw 24 GHz data shows PH winning (-8%) but this is entirely the Great Lakes firing squad — with manufactured contacts removed, CW leads by 16%.
+
+**SSB is not possible on rainscatter.** FM is the mode used for rainscatter on 24 GHz.
+
+At 75+ GHz, SSB is only viable for short-range contacts (median 13 km vs CW's 57 km). Above 122 GHz, 100% of contacts in the dataset are CW.
+
+See `docs/findings10.md` for full regional breakdown and statistical analysis.
 
 ### Finding 11: Regional Performance Varies but Is Not Algorithm-Correctable
 
@@ -1070,7 +1078,7 @@ end
 
 ### Score Tiers with Per-Band Range Estimates
 
-Range estimates are for CW mode. For SSB/phone, reduce by ~20%. For FM, reduce by ~40%.
+Range estimates are for CW mode. For SSB/phone, reduce by ~25% at 10 GHz, ~15% at 24 GHz, ~50% at 47 GHz, ~70% at 75+ GHz. For FM, reduce by ~40%.
 
 Database stats for reference: 10G avg=213 km, P90=383 km, max=2,393 km. 24G avg=98 km, P90=179 km, max=710 km. 47G avg=66 km, P90=122 km, max=343 km. 75G avg=64 km, P90=177 km, max=289 km.
 
@@ -1490,7 +1498,7 @@ For surface ducts, the beam must arrive at <0.5° grazing incidence to be trappe
 **Key variable:** Absolute humidity (22.235 GHz H2O line makes this THE most humidity-sensitive band)
 **Best conditions:** Very dry air (<8 g/m^3), cold season (Nov-Mar), clear skies, pre-dawn through early morning
 **Night enhancement:** +28% avg distance, +16% P90 vs afternoon (119.7 km vs 93.8 km)
-**Dataset:** 3,639 QSOs, avg 98 km, P90 179 km, max 710 km (rainscatter CW).
+**Dataset:** 3,639 QSOs, avg 98 km, P90 179 km, max 710 km (CW). Note: raw PH average exceeds CW at 24 GHz due to Great Lakes contest manufacturing — with cluster activity removed, CW leads by 16% (see Finding 10).
 **Unique:** 10x more sensitive to water vapor than 10 GHz. Summer Gulf moisture devastates range. Rain scatter is a viable alternative mechanism (710 km QSO documented). March is the worst ducting month (10.8%) but also has low humidity, creating a tension between ducting availability and absorption loss.
 
 ### 47 GHz (6mm) — Atmospheric Window
@@ -1624,7 +1632,7 @@ For each band:
 | Non-ducting gradient avg | -123 N/km | Sounding avg for non-ducting events |
 | Ducting surface N threshold | 330 | Above this, ducting probability >50% |
 | Signal prediction floor | +/- 2-3 dB | Measured from link data |
-| CW bandwidth advantage | ~7 dB | 10*log10(2700/500); 24% range increase |
+| CW bandwidth advantage | ~7 dB | 10*log10(2700/500); 16-221% range increase depending on band |
 | Pressure correlation (10 GHz) | rho=-0.180 | 57,248 QSO-HRRR analysis, Apr 2026 |
 | PWAT optimal range (10 GHz) | 20-30 mm | Best median distance (219 km) |
 | PWAT correlation (75 GHz) | rho=-0.608 | 57,248 QSO-HRRR analysis, Apr 2026 |