tools / cw decoder v2.0 beta

CW Decoder v2.0

Real-time Morse decoder. Feed audio from your radio or microphone — the Goertzel filter isolates the CW tone and decodes it live.

reference chart

v2.0 betaTwo rebuilds over v1. Character framing is derived from the timing it actually measures rather than from fixed gap thresholds, so it holds together above 25 WPM and stops shattering slow characters into their own elements. The display was also moved off the audio callback, which should take the sluggishness out of the UI. Expect a practical ceiling around 45–50 WPM — past that the filter block is too coarse to measure a dit reliably. The WPM range is a single two-handled slider, and the speed estimate is held inside it: narrow it and noise can no longer run the estimate up to an implausible speed, widen it if the decoder sits pinned at one end of the range. There is also an optional run-together split under gap sensitivity, which uses the spacing between elements to pull apart characters sent without a full gap — BK, AA, CQ and so on. It is off by default, and anything it resolves is shown dimmed, since it is a judgement call rather than a clean read. The stable version is still at cw decoder. Feedback welcome.

input

microphoneline-in

Picks up CW from your radio speaker. Auto-gain adjusts for distance.

tuning

Frequency

Signal

Gate

Noise gate — ignores signal below this level. Raise to cut background noise.

Bandwidth

200 Hz

Filter bandwidth around the target tone. Narrow to reject nearby signals on a crowded band.

timing

WPM range

5–40

The speed estimate is held inside this range. Narrow it to stop noise running the estimate away; widen it if the decoder sits pinned at one end.

Live WPM

lock—

gap sensitivity

Letter gap

2.5

Word gap

5.5

Lower = splits letters sooner. Raise if letters are splitting incorrectly. Standard Morse: letter 3, word 7.

Run-together

split

Uses the gaps between elements to pull apart characters sent without a full space — BK, AA, CQ and the like. Resolved characters are shown dimmed, because it is an inference rather than a clean read.

V2.0 BETA

tone

cw decode

audio in

tone

Audio in reads soundcard level, not calibrated signal strength — it follows your radio’s AF gain. The tone dial shows what the decoder hears after filtering, with its detection threshold marked.

spectrum

waterfall

400500600700800900

decoded output