A Propagation Display That Runs on the Pi
A HamClock-style propagation page for the station console: solar numbers, color-coded band conditions, a grey-line world map drawn on the Pi itself, and live band activity heard near the QTH.
Overview
Propagation is the question every HF operator asks before keying up: what is open, and to where. This is a page on the station console that answers it at a glance, with as much as possible computed on the Pi rather than pulled from a paid service.
It shows four things: the current solar numbers, band-by-band conditions, a grey-line map of where it is day and night, and what the station is actually hearing, by band.
The grey-line map, drawn locally
The day/night terminator is computed on the Pi from the sun’s position for the current moment, then drawn over a plain world map. The subsolar point (where the sun is overhead), the station’s own location, and the stations recently heard are marked on it. It refreshes on its own every couple of minutes.
Drawing it locally means no external map service and no API budget. The only thing it needs is the clock and a little math.
Conditions, band by band
Each HF band gets a color-coded condition and its frequency ranges, with the usual FT8, SSB, and CW tune-to spots called out. The solar indices that drive those conditions come from the standard public solar feed. This is the “should I even try” layer.
What the station is actually hearing
Modeled conditions are a forecast. The more honest signal is what your own corner of the world is receiving right now, so the page also pulls live reception data near the QTH: per-band counts of what is being heard, and which stations. It is cached for a few minutes so it stays quick and does not hammer the source.
Together, the forecast and the live activity answer the real question better than either one alone.
Lessons
- Compute what you can locally. The grey line is just the sun’s position and some trigonometry. No service, no key, no rate limit, and it works offline.
- Pair the model with the measurement. Band-condition models tell you what should be open. Live reception tells you what is. Show both.
- Cache the slow things. A few minutes of caching on the external pulls keeps the page snappy and polite to the sources.