PhosphorFAX
HF Weather Fax Decoder
Only for iPhone
$0.99 · Designed for iPhone. Not verified for macOS.
iPhone
Weather charts from the ether.
Hold your iPhone to a shortwave radio and watch coast-station radiofax paint itself line by line. No internet, no account, no hardware.
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.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Stuart Woolley, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Stuart Woolley
- Size
- 2.7 MB
- Category
- Weather
- Compatibility
Requires iOS 27.0 or later.
- iPhone
Requires iOS 27.0 or later. - Mac
Requires macOS 27.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 27.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Stuart Woolley
