How to use it
- Select Microphone or System or tab audio. Shared system audio depends on browser and operating-system support.
- Press Start listening and grant the requested permission.
- Place the threshold above background noise but below the active CW signal.
- Watch Peak tone, Signal, Timing, Live Morse, and confidence-colored decoded text.
- Use Clear to begin a new session or copy the decoded text for your own notes.
Decoder mechanics
The decoder analyzes audio locally in the browser. It searches a narrow 350-1000 Hz CW range, tracks the strongest stable tone, estimates its envelope, and classifies tone and gap durations against an adaptive Morse timing model.
Character colors express confidence from timing fit and signal stability. A low-confidence character is a warning, not a second hidden result. Audio is not uploaded or stored by CW599.
Accuracy and limitations
Best results come from a single clean CW tone with stable speed. Speech, music, multiple stations, fading, automatic gain changes, severe noise, or an off-frequency signal can split or join characters incorrectly. This browser tool is intended for practice and assistance, not safety-critical or regulatory use.
Versions and archives
v1.1 aligns the narrow-screen content gutter with the site header, without changing microphone permissions, local decoding, or audio handling. v1.0 introduced local microphone and shared-audio decoding, adaptive timing, live Morse, and confidence-colored output.
Version archive
When a retired release has a runnable snapshot, this list will link both its documentation and the archived tool. Earlier releases without a snapshot are explicitly marked documentation only.