PhosphorCW

PhosphorCW — Morse Code Decoder

Decode CW (Morse code) signals in real time using your iPhone or iPad's microphone. PhosphorCW listens to radio audio and prints decoded text on screen with the warm glow of a vintage phosphor terminal.

REAL-TIME DECODING

Point your device at a radio speaker or feed audio via a line-in adapter. PhosphorCW's DSP engine continuously processes the audio stream, detecting CW tones and decoding them into readable text as they arrive. Characters appear on a teleprinter-style display that scrolls automatically, just like the machines that once clattered in radio rooms and newsrooms worldwide.

AUTOMATIC SIGNAL TRACKING

• Auto Frequency (AFC) — Automatically finds and locks onto the CW sidetone using FFT peak detection. No need to know the exact tone frequency. The tracker adapts as conditions change.

• Auto Speed — Measures dit and dah timing to determine sending speed in words per minute. Adapts continuously from around 5 to 60 WPM as the operator's speed varies.

Both can be switched to manual mode for fixed-frequency or fixed-speed operation.

ON-DEVICE DSP ENGINE

All signal processing happens locally on your device. Nothing is recorded, transmitted, or stored externally.

The decoding pipeline includes:

Bandpass filtering centred on the detected tone frequency
Goertzel-based tone detection with adaptive noise floor tracking
Envelope extraction with slow-decay peak tracking for reliable squelch
Adaptive timing estimation for dit/dah discrimination and character/word gap detection
Full ITU Morse code table including prosigns
SIGNAL ANALYSIS

A dedicated signal view provides:

Live FFT spectrum display showing the audio frequency content
Scrolling waterfall display for visualising signal activity over time
Tone level indicator
Real-time WPM, tone frequency, and SNR readout
Lock status indicator showing when AFC has acquired a signal
DISPLAY

Choose from multiple phosphor colour themes — green, amber, white, and blue — inspired by th…