PhosphorRTTY vs VibeSDR

PhosphorRTTY decodes Radio Teletype (RTTY) signals in real time using your iPhone's microphone. Hold your phone 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 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 all standard configurations: Baud rates: 45.45, 50, 75, 100 Bd (auto-detected or manual) Shifts: 85, 170, 450, 850 Hz (auto-detected or manual) ITA2 (Baudot) and ASCII modes USB and LSB conventions 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 with an authentic mechanical delay. Status bar shows baud rate, shift, mark/space frequencies, and signal lock state. Clear, pause, and session controls. SIGNAL — Live signal analysis. FFT spectrum display (0–4 kHz), scrolling waterfall, mark/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. CONFIG — All parameters. Audio input gain, decode mode (auto/manual for baud, frequency, and shift), display theme, font size, bell character handling, and RYRY sequence display options. THE DISPLAY Two authentic phosphor CRT themes: Amber (classic teleprinter terminal) Green (military/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 W7AY Automatic Threshold Correction 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 20m and 40m amateur bands. Under 1% error rate on clean signals, 4–5% on moderate HF conditions with fixed tuning. WHERE TO FIND RTTY Amateur radio: 14.080–14.099 MHz (20m band), 7.080–7.100 MHz (40m band), 21.080–21.100 MHz (15m band). RTTY contests run throughout the year — 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 with microphone iOS 17 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.

VibeSDR is a mobile-first software-defined radio (SDR) receiver — and far more than a single-server client. It speaks multiple SDR server protocols and does its own demodulation of the raw IQ with a clean-room DSP engine. Pair that with a GPU-rendered waterfall, native background audio, on-device decoders and maps, plus voice and in-car control, for a genuinely great SDR experience on any iPhone — whatever receiver is behind it. WHAT YOU CAN CONNECT TO • Remote SDR servers — native support for UberSDR, OpenWebRX / OpenWebRX+, and KiwiSDR, all behind one interface, with a directory chooser in the instance picker. • Networked rtl_tcp — connect to a remote rtl_tcp server and VibeSDR demodulates the raw IQ itself. DISPLAY & WATERFALL • Custom GPU waterfall and spectrum, rendered with a Skia shader for a smooth, high-frame-rate display independent of the server. • Portrait and landscape layouts, ProMotion 120 Hz, haptic tuning feedback. • Classic colour palettes (GQRX, KiwiSDR, CuteSDR, SdrDx, OpenWebRX), VFO glow controls, and a spectrum backdrop image. TUNING & CONTROLS • VFO drum with inertia scrolling and a dual-drum waterfall zoom. • Full mode set — USB, LSB, AM, SAM, FM, NFM, CW — with passband sliders. • Noise reduction, noise blanker, squelch, AGC, volume and mute. AUDIO • Native audio engines running outside any WebView, so playback survives app suspension. • Background audio on both platforms. • Lock-screen, Now Playing, CarPlay and Apple Watch controls with frequency + station metadata and station/bookmark skipping. • AAC recorder with share sheet. VOICE CONTROL • Siri — "Hey Siri, tune VibeSDR" then a frequency, a station name, or a band; it tunes with the right demodulator and step, even in the background over headphones, CarPlay or the lock screen. DECODERS & MAPS • On-device decoders — RTTY, NAVTEX, WEFAX, SSTV, Morse, and speech-to-text. • Server maps — HFDL aircraft, digital and CW activity maps, fully embedded. STATIONS & BOOKMARKS • Instance picker directory across UberSDR, OpenWebRX/OpenWebRX+ and KiwiSDR receivers, with country flags, favourites and an auto-connect default. • Bookmark and band-plan search with live EiBi schedules. • Visual Tuning System (VTS) — nearby-station bar, band-crossing popups and station skipping. • Live chat, and Share a tuned station as a tappable deep link. NEW: DEEP LINKING • Tap a vibesdr:// link to connect straight to a receiver and tune to the shared frequency — no hunting through the picker. VibeSDR is free software under the GNU GPL-3.0, built by Stuart Carr with AI assistance from Claude (Anthropic). VibeSDR is a receiver client and is not affiliated with the SDR servers it connects to.