PhosphorCW decodes CW (Morse code) signals in real time using your iPhone's microphone. Hold your phone near a shortwave radio tuned to a CW signal and watch the text appear on an authentic phosphor CRT display, character by character.
No internet connection required. No external hardware. No account. Just your iPhone and a radio.
FEATURES
- Real-time CW (Morse code) decoding via microphone
- Automatic frequency control (AFC) acquires and tracks drifting CW tones
- Adaptive speed detection — auto-tracks WPM from incoming signal
- Manual speed entry (5–60 WPM) and tone frequency selection (300–1500 Hz)
- Live FFT spectrum display, scrolling waterfall, and Morse element strip
- Session logging with full decoded text, timestamps, and signal parameters
- Amber and green phosphor CRT themes with scanlines, vignette, and glow effects
- International Morse Code including punctuation and prosigns
- No accounts, no tracking, no network access
DSP ENGINE
Per-sample I/Q quadrature demodulation with biquad low-pass filtering, hysteresis comparator for key state detection, and adaptive dit/dah classification with moving-average speed tracking. 512-point FFT for frequency analysis and AFC. All signal processing runs entirely on-device.
DECODER ACCURACY
PhosphorCW has been tested against real over-the-air CW recordings, ARRL W1AW code practice transmissions, and historical hand-keyed Morse. Detailed test results, methodology, and decoded output samples are available in the decoder test report.
WHERE TO FIND CW
- 20m band: 14.000–14.070 MHz
- 40m band: 7.000–7.040 MHz
- 15m band: 21.000–21.070 MHz
- W1AW code practice: 18.0975, 14.0475, 7.0475 MHz
A shortwave receiver, SDR, or WebSDR audio played through a speaker is all you need.
SUPPORT
Need help? Have a question, bug report, or feature request?
- Ask a question — get help with using PhosphorCW
- Report a bug — let us know if something isn't working
- Request a feature — suggest improvements or new functionality
You can also browse existing issues to see if your question has already been answered.