FEMA Region 6 • Texas ARES • AF MARS 6th Comm Wing
The dashboard recommends frequencies based on current foF2 and empirical propagation data.
foF2 is the critical frequency — the maximum frequency that reflects vertically from the F2 layer. For NVIS (0-300 mile range), use frequencies below foF2. Rule: Optimal NVIS = 85% of foF2. Data priority: Direct ionosonde → Regional interpolation → GPS TEC → IRI model. WSPR badges show real-world propagation verification.
NVIS propagation is highly time-dependent. Use this guide for initial band selection, then verify with live data above.
| Time (Local) | Primary Band | Secondary | Notes |
|---|---|---|---|
| 0600–1000 | 40m (7 MHz) | 60m (5 MHz) | Ionosphere forming — 80m absorption increasing |
| 1000–1600 | 40m (7 MHz) | 30m (10 MHz)* | Peak D-layer absorption kills 80m; *30m near solar max only |
| 1600–2000 | 40m / 60m | 80m (3.5 MHz) | Transition — 80m opening as D-layer fades |
| 2000–0600 | 80m (3.5 MHz) | 60m (5 MHz) | 40m may skip over regional targets at night |
60m (5 MHz) provides the most stable 24-hour NVIS path. Times approximate for Central Texas (EM10) latitude.