Fourteen decoders, one click each
The decoders run in the listener's own browser, each in its own Web Worker, so decoding never competes with the audio or the waterfall. They read the raw audio — the noise filters you set for listening never change what decodes.
Copy what you cannot hear
FT8FT815 s cycles
The most popular weak-signal mode, decodable 20–25 dB below the noise. Decodes are marked on the spectrum, and the SNR agrees with WSJT-X.
FT4FT4 & FT27.5 s / 3.75 s
The faster contest variant and the experimental ultra-fast FT2, both on the same engine as FT8 and with a real SNR.
JS8JS8conversation
JS8Call's keyboard-to-keyboard mode, shown as a conversation panel with multi-frame messages put back together. Measured within 0.5 dB of JS8Call on the same audio.
WSPRWSPR2 min slots
The propagation beacon mode, decoded in full two-minute UTC slots with a port of the reference wsprd decoder.
CWCW — Morse code
A coherent weak-signal Morse decoder that tracks the signal, adapts to the sender's speed — including Farnsworth and slow sending — and gates out noise.
QRSSQRSS grabberlook, don't listen
Very slow CW from low-power beacons, pulled out 20–30 dB below the noise by a long FFT and painted as the classic grabber display, with a list of the band windows.
Maritime, weather and amateur teleprinter
⚓NAVTEX
Maritime safety broadcasts — navigational warnings, weather and search-and-rescue notices — on 518 kHz, 490 kHz and the five HF channels, with message framing and headers recognised.
⌨️RTTY, PSK31 & Olivia
One window with five presets: Maritime FSK / SITOR, Weather RTTY, Amateur RTTY, PSK31 and Olivia. RTTY and PSK31 show a real SNR, and RTTY has its own squelch.
| Variant | Shift | Baud | Encoding |
|---|---|---|---|
| Maritime FSK / SITOR | 170 Hz | 100 | CCIR-476 |
| Weather RTTY | 450 Hz | 50 | ITA2 |
| Amateur RTTY | 170 Hz | 45.45 | ITA2 |
| PSK31 (BPSK) | — | 31.25 | Varicode |
| Olivia (MFSK) | — | by mode | 7-bit + FEC |
🗺️HF fax / WEFAX
Weather maps and sea-state charts from coast guard and meteorological stations, rebuilt line by line. Pick one of over 20 stations worldwide, press Tune, and the receiver goes there in USB. Start, stop and phasing are detected automatically.
🖼️SSTV
Slow-scan television pictures from an ordinary SSB channel — Martin, Scottie, Scottie DX and Robot — with the mode found automatically from the VIS header or, if that was missed, from the sync timing. 14.230 MHz is the place to start.
FreeDV RADE V1
RADE is FreeDV's machine-learning digital voice mode, which keeps speech readable at signal levels where SSB is just noise. The RADEL and RADEU buttons beside the mode selector start it on the lower or upper sideband in one press — on the desktop page and on /mobile.
Decoding runs on the server in a small sidecar process the installer sets up.
Also in the audio chain
- C-QUAM AM stereo — detected automatically; the QUAM label turns green.
- Synchronous AM — locks on the carrier against selective fading.
“What am I listening to?”
Tune an unknown digital signal and switch Decoder ID on. After about half a minute it names the mode with a confidence figure and shows the evidence — bandwidth, tone spacing, symbol rate, timing grid and SNR — then offers the right decoder in one click, with the receiver set up for it.
Off by default. It goes quiet on very weak signals rather than guessing.
Decoder ID [On] NAVTEX / SITOR-B 99%
170 Hz shift · 100.00 Bd · 43 dB S/N
[ Use NAVTEX ]
The receiver reports what it hears
A built-in autorun engine on the server decodes off-air signals around the clock, whether or not anyone is listening, and uploads the reception reports itself — no WSJT-X, no extra computer.
📍FT8, FT4, JS8 → PSK Reporter
Over PSK Reporter's native IPFIX protocol, batched at the recommended interval of at least five minutes. JS8 group destinations and unresolved callsigns are never reported.
🌍WSPR → WSPRnet
Through the standard WSPRnet upload, and only there, so no spot is ever counted twice.
Frequencies, settings and tips
The decoder manual lists the recommended frequencies for every mode, each decoder's controls and how to read its output.