
PhosphorFAX
HF Weather Fax Decoder
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$0.99
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About
PhosphorFAX receives radiofax, the HF weather fax that coast stations broadcast around the clock, and paints each chart line by line on a phosphor CRT display. Hold your iPhone near a shortwave receiver tuned to a weather fax station and watch surface analyses, wind and wave forecasts and ice charts arrive the way they do on a ship's recorder.
It sends as well. Turn a photo, a received chart or the built-in test card into radiofax audio through the speaker, or export it as a WAV.
No internet connection. No external hardware. No account. Just your iPhone and a radio.
HOW TO RECEIVE
Tune your receiver 1.9 kHz below the station's listed frequency in USB, so the signal sits around 1900 Hz. Then on the DECODE screen:
ARM: wait for a start tone, then receive automatically
START: receive now, without waiting for a start tone
STOP: end the chart and save it
CLEAR: discard the chart in progress
Drag to look around the chart, and LATEST takes you back to the newest line
Pinch to zoom, double-tap to fit
The same guide is on the DECODE screen until a chart appears.
HOW LONG IT TAKES
Radiofax is slow, and that is part of its charm.
• The start tone lasts 5 seconds and is recognised within a second or two.
• Phasing follows, up to 30 seconds, while PhosphorFAX locks onto the start of each line. If no phasing is heard, receiving begins anyway after 40 seconds.
• A chart paints from the top at two lines a second at 120 LPM. A full chart takes about 10 minutes, 20 at 60 LPM and 5 at 240 LPM. In the first minute you will see only a thin strip, so give it time.
• On the stop tone the chart is saved to the log and the receiver re-arms for the next one.
• Sending takes as long as receiving: about 10 minutes for a chart at 120 LPM, longer for a tall photo. PhosphorFAX shows the duration before anything plays.
FEATURES
• Real-time radiofax receive at IOC 576 and 288, 60 to 240 lines per minute
• Automatic start and stop, re-arming after every chart
• Phasing lock and automatic slant correction for straight charts
• Automatic centre tracking
• Charts can be re-slanted and shifted after the broadcast has gone
• Live spectrum, waterfall, line scope and signal health panel
• Station list for 22 coast and met stations worldwide, with USB dial frequencies
• Chart log with zoom, levels, rotation, invert, share and save to Photos
• Send a photo, a chart or a test card, or export it as a WAV
• Paper, phosphor or negative chart rendering
• Green and amber phosphor CRT themes
• No accounts, no tracking, no network access
SENDING
PhosphorFAX produces audio and never keys a transmitter. Putting that audio on the air needs an appropriate transmitting licence. Sending into a second phone, or exporting a WAV, needs none.
Colour fax is not supported.
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What's New in PhosphorFAX
1.0
October 17, 2026









