Audio file
Drop a recording anywhere on this page, or pick one. WAV keeps its own sample rate; other formats are resampled by the browser.
Microphone
Hold a receiver up to the microphone, or feed it from a virtual audio device. Needs HTTPS or localhost. The screen is kept awake while this is running.
- Mode
- —
- State
- idle
- Rows
- —
- Input level
- Frequency offset
- —
- Effective sample rate
- —
- FSKID
- —
What decodes
Robot 36 and 72, Scottie 1, 2, and DX, Martin 1 and 2, and PD50, 90, 120, 160, 180, 240, and 290. Any other mode is identified from its VIS and then reported as having no decoder, which is what the desktop application does too.
Microphone audio must not be processed
The page asks the browser to turn echo cancellation, noise suppression, and automatic gain control off, because each one attacks something the decoder needs: noise suppression treats a steady tone as stationary noise and attenuates it, gain control reshapes the envelope the sync detector scores, and echo cancellation mis-adapts against a continuous signal with no far end. The browser cannot reach processing the operating system applies to the device, so turn off Windows audio enhancements or macOS voice isolation as well.