PhosphorRTTY
RTTY Decoder: Ham & Shortwave
0,99 € · Designed for iPad. Not verified for macOS.
Also Included In
Hold your iPhone or iPad to the radio and watch RTTY print as it arrives. Auto baud, shift and tuning, a live waterfall, no account, no ads, nothing leaves the device.
PhosphorRTTY decodes Radio Teletype (RTTY) signals in real time using your iPhone or iPad microphone. Hold it near a shortwave radio tuned to an RTTY signal and watch the text appear on screen, character by character, on an authentic phosphor CRT display.
No internet connection required. No external hardware. No account. Just your iPhone or iPad and a radio.
WHAT IT DECODES
RTTY is the oldest digital mode in amateur radio: two audio tones representing mark and space, encoding text via the 5-bit ITA2 (Baudot) alphabet or 7-bit ASCII. PhosphorRTTY handles the standard configurations:
Baud rates: 45.45, 50, 75, 100 Bd (auto-detected or manual)
Shifts: 170, 450, 850 Hz (auto-detected or manual)
ITA2 (Baudot) and ASCII modes
USB signals, and LSB signals with mark and space inverted
AUTOMATIC SIGNAL DETECTION
The app automatically finds and locks onto RTTY signals:
AFC (Automatic Frequency Control) acquires and tracks drifting signals
Auto-baud detection identifies the transmission speed
Auto-shift detection determines the frequency separation
Squelch suppresses noise when no signal is present
Or disable any of these and tune manually for full control.
FOUR TABS
DECODE: the main teleprinter display. Decoded text appears character by character as it is received. The status panel shows baud rate, shift, mark and space frequencies, signal quality and lock state. Clear, pause and resume, start and stop.
SIGNAL: live signal analysis. FFT spectrum display (0 to 4 kHz) with mark and space cursors, scrolling waterfall, mark and space tone indicators, bit period histogram with baud rate markers, and a paper punch tape visualisation of the decoded data stream.
LOG: session history. Every decode session is saved with timestamp, duration, character count and the full decoded text. Copy, share or delete individual sessions, or export them all at once.
CONFIG: all parameters. Audio input gain, decode mode (auto or manual for baud, frequency and shift), ASCII mode, mark and space inversion, display theme, font size and RYRY sequence display options.
IPHONE AND IPAD
On iPad PhosphorRTTY runs natively in every orientation, with larger type and the teleprinter, spectrum, waterfall and punch tape opened out across the full width of the screen.
THE DISPLAY
Two authentic phosphor CRT themes:
Amber (classic teleprinter terminal)
Green (military and commercial terminal)
Both feature horizontal scanlines, edge vignette and phosphor glow effects.
Monospaced font throughout. RYRY test sequences can be dimmed or hidden to keep the display clean.
DSP ENGINE
The signal processing is done entirely on-device using a per-sample I/Q quadrature demodulation pipeline:
Biquad low-pass filtered I/Q channels for each tone
Direct mark and space magnitude comparison for bit decisions
Digital Phase-Locked Loop (DPLL) with per-transition phase correction for timing recovery
512-point FFT for frequency analysis and AFC
Asymmetric envelope detection for robust tone tracking through fading
Tested against real over-the-air recordings from the 20m amateur band. Under 1% error rate on clean signals, 4 to 5% on moderate HF conditions with fixed tuning.
WHERE TO FIND RTTY
Amateur radio: 14.080 to 14.099 MHz (20m band), 7.080 to 7.100 MHz (40m band), 21.080 to 21.100 MHz (15m band). RTTY contests run throughout the year, and during a contest these frequencies are packed with signals.
Maritime and commercial RTTY transmissions can be found across the HF spectrum. A shortwave receiver or SDR with audio output is all you need.
REQUIREMENTS
iPhone or iPad with a microphone
iOS or iPadOS 26.2 or later
A radio receiver tuned to an RTTY signal (shortwave radio, SDR, or WebSDR audio played through a speaker)
No in-app purchases. No subscriptions. No tracking. No network access.
Ratings & Reviews
- This app has not received enough ratings or reviews to display an overview.
The first version for iPad.
PhosphorRTTY now runs natively on iPad, in every orientation, with larger type and the teleprinter, spectrum, waterfall and punch tape opened out across the full width of the screen.
Decoding behaves better on every device. ASCII RTTY now shows the ASCII text alone, PAUSE holds what is decoded and releases it when you resume, DIMMED now dims RYRY sequences, and each saved session records the signal it actually decoded.
The LOG screen gains an EXPORT ALL button, the mark and space labels on the spectrum no longer overprint each other, and the status bar now 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
- Size
- 4.6 MB
- Category
- Utilities
- Compatibility
Requires iOS 26.2 or later.
- iPhone
Requires iOS 26.2 or later. - iPad
Requires iPadOS 26.2 or later. - Mac
Requires macOS 26.2 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 26.2 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Provider
Stuart Woolley
- Stuart Woolley has identified itself as a trader for this app and confirmed that this product or service complies with European Union law.
- Address
LIssatunna
Ennistymon Clare V95Y8N1
Ireland - Phone Number
+353 868108703 - Email
restyle_hairs7c@icloud.com
- Copyright
- © 2026 Stuart Woolley
