Approximate model. This page uses a self-contained simplified ionospheric model
(solar-zenith-driven
foF2, hop geometry, ITU-style D-layer absorption, ITU-R P.372 noise).
It reproduces the
shape of HF openings well but is not VOACAP. Treat numbers as
indicative, ±1–2 S-units. For a decision-grade prediction run
VOACAP Online.
Circuit reliability →
<5%
10
25
40
55
70
85
95%+
Hover any cell for distance, MUF, hops, take-off angle, signal and SNR — and the LIVE column for the WSPR detail.
How the numbers are produced