PhosphorTEX
NAVTEX Decoder & Receiver
₹ 99 · Designed for iPad. Not verified for macOS.
Also Included In
Hold your iPhone or iPad to the radio and read NAVTEX gale warnings, navigational hazards and rescue notices as they arrive.
No account, nothing leaves the device.
PhosphorTEX decodes NAVTEX maritime safety broadcasts in real time on your iPhone or iPad. Tune a receiver to 518 kHz, 490 kHz or 4209.5 kHz, hold your device near the speaker, and watch navigational warnings, gale warnings, ice reports and search-and-rescue notices arrive on an authentic phosphor CRT display.
No internet connection required. No account. Nothing leaves the device.
WHAT NAVTEX IS
NAVTEX (Navigational Telex) is the worldwide maritime safety broadcast of the IMO's Global Maritime Distress and Safety System (GMDSS). Coast stations send storm warnings, navigational hazards, search-and-rescue notices and weather forecasts to ships at sea, each station in its own ten-minute slot. PhosphorTEX puts that live feed on your screen.
SIGNAL PROCESSING
PhosphorTEX decodes CCIR 476 SITOR-B entirely on the device, with signal processing written for the app:
Synchronous 7-bit decoding with phase-locked clock recovery
Automatic character alignment that finds the character boundary on its own
Automatic polarity detection, so maritime receivers and SDR tuning both work with no toggles
Automatic frequency control that finds and tracks the 170 Hz tone pair anywhere from 800 to 2500 Hz
Every character checked against the NAVTEX error code, with errors shown rather than guessed
Error statistics for every message, measured against the second copy NAVTEX sends of each character
Live 512-point FFT spectrum and scrolling waterfall
FIVE TABS
DECODE: every message as a colour-coded card, with the station letter, subject, serial number, UTC time, a signal quality badge and the full text. Switch to TAPE for the raw teleprinter stream.
SIGNAL: FFT spectrum with mark and space cursors, a scrolling waterfall, mark and space tone bars, and an FEC HEALTH panel showing how cleanly each character arrived.
SCHEDULE: a built-in database of 43 NAVTEX coast stations across thirteen NAVAREAs, from Cullercoats, Niton and Malin Head to Reykjavik, Las Palmas, Singapore and Valparaíso. A live grid shows which stations transmit in the current ten-minute slot against a running UTC clock.
LOG: every decoded message kept on the device, with its header, time, full text and error statistics. Copy, share or delete a message, or export them all as text.
CONFIG: amber or green phosphor, three text sizes, automatic or manual tuning, mark and space inversion, alert colours for search-and-rescue and vital messages, and a mute list for subjects you do not want on the cards. Search-and-rescue messages can never be muted.
IPHONE AND IPAD
On iPad PhosphorTEX runs natively in every orientation, with larger type and the cards, spectrum, waterfall and station schedule opened out across the full width of the screen.
PRIVACY
PhosphorTEX makes no network requests. No account, no cloud, no analytics, no tracking, no third-party code. Audio is processed in memory as it arrives and is never recorded, stored or sent anywhere. The microphone is used only while decoding.
WHERE TO FIND NAVTEX
518 kHz carries the international service in English, 490 kHz carries national services in local languages, and 4209.5 kHz carries the tropical HF service. Any receiver that covers these frequencies with SSB will do, and so will WebSDR audio played through a speaker.
REQUIREMENTS
iPhone or iPad with a microphone
iOS or iPadOS 26.4 or later
A receiver tuned to a NAVTEX frequency, or WebSDR audio played through a speaker
No in-app purchases. No subscriptions. No tracking. No network access.
PhosphorTEX is part of the Phosphor range of retro-CRT radio tools, alongside PhosphorRTTY, PhosphorCW, PhosphorFeld and PhosphorSSTV.
Ratings & Reviews
- This app has not received enough ratings or reviews to display an overview.
The first version for iPad.
PhosphorTEX now runs natively on iPad, in every orientation, with larger type and the message cards, spectrum, waterfall and station schedule opened out across the full width of the screen.
The settings do what they say. SUBJECT MUTE hides the subjects you mute from the cards, the ALERTS switches decide whether search-and-rescue and vital messages are drawn in the alert colour, and the TAPE DELAY setting, which had no effect, is gone. PAUSE holds what is decoded and releases it when you resume, rather than cutting into the message being received.
The error statistics count correctly. The RX badge and the FEC HEALTH panel show only the errors the second copy of a character could put right, so a clean message reads DX. The LOG screen gains an EXPORT ALL button, and the status bar tells you when the microphone is unavailable or interrupted.
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
- Provider
- Stuart Woolley
- Size
- 5 MB
- Category
- Utilities
- Compatibility
Requires iOS 26.4 or later.
- iPhone
Requires iOS 26.4 or later. - iPad
Requires iPadOS 26.4 or later. - Mac
Requires macOS 26.4 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 26.4 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Stuart Woolley
