PhosphorHertz
Stuart Woolley
Getting the latest details from the App Store…
PhosphorHz is a real-time HF radio propagation monitor for amateur radio operators. It pulls live space weather data from NOAA's Space Weather Prediction Center and translates it into band-by-band conditions you can act on — right now, from your location. No guesswork. No stale forecasts. Just the numbers, rendered in a retro CRT phosphor display that would look at home in a Cold War listening post. BAND CONDITIONS See at a glance which HF bands are open, marginal, closed, or blacked out…
Top of Paid · Utilities in India. PhosphorHertz is #24 there. Changes are over 7 days.
How the app presents itself on the App Store. Select a screenshot to open it full size.
Version 2.0 · 11 Oct 2026 · 1 day ago
A rebuild of PhosphorHz inside and out, and the first version for iPad. Band forecasts now come from the real ionosphere. PhosphorHz reads NOAA's GloTEC, a global map of the ionosphere built every ten minutes from GPS and satellite measurements, and works out the usable frequency of every path from it. Long paths are worked out hop by hop, so a distant contact is judged by its weakest reflection. PhosphorHz now runs natively on iPad as well as iPhone, with larger type and a layout opened out for the bigger screen. The interface has been redrawn around a standard tab bar, BANDS, INDICES, ALERTS, MAP and SETUP, with help for every page from a single button. BANDS gains a DX PATHS table giving the bearing, distance and usable frequency for each target, and whether the middle of each path lies in daylight, on the greyline or in darkness. Up to five DX targets now sit in fixed slots, added from a list of regions or your own coordinates. The Kp and solar flux charts are taller, with proper time scales, and the Kp chart keeps the same warning colours in both green and amber. Under the hood, sunrise, sunset, the greyline and the day and night terminator now come from the same astronomy engine as our other sky apps, checked against the US Naval Observatory and NASA JPL. PhosphorHz opens straight onto the last data it received while fresh data loads, any data page can be pulled down to refresh, and each NOAA feed is fetched as often as it actually changes. And a new app icon.
Every chart this app is in right now, best position first.
| Chart | Rank | 24 h | 7 days | Best | Days on chart |
|---|---|---|---|---|---|
| India· Paid · Utilities | #24 | New entry | Change unknown | #24 | 1 |
Higher on the chart is better: #1 is at the top.
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India · Paid · Utilities: best #24, latest #24, over 10 snapshots since 8 Oct. No snapshots from 8 Oct to 9 Oct, on 9 Oct, on 10 Oct, on 11 Oct, and on 12 Oct; the line joins the snapshots on either side.
Entries, big moves, #1s and new versions we've recorded.
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