SimpleCW vs PhosphorRTTY

Read Morse and digital-mode signals from audio with SimpleCW (formerly HamChat). Tune one receiver, watch the waterfall, and follow decoded text in the transcript. CW includes automatic tone acquisition or manual tuning, Otsu and Bayesian decoders, a live keying trace, speed estimates, and input-level feedback. An optional on-device ML CW decoder is included with Premium Modes Unlock on iOS 18 or later and macOS 15 or later. Decoder results depend on signal quality and sending style; Otsu is the default. Receive CW, PSK31/63, MFSK, Olivia, and RTTY. Classical receive in every mode and CW transmit remain free. A three-minute trial lets you try other transmit modes. The existing one-time Premium Modes Unlock purchase adds unlimited digital-mode transmit and the optional ML CW decoder. Use the microphone or a compatible audio interface. On Mac, System Audio can receive audio from other software with the appropriate system permission. Audio processing stays on the device. Copy or share the resulting transcript.

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.