Signal search with waterfall and mode detection
Which signal is that? The signal search shows a waterfall of a recording or the receiver output, finds all signals above the noise and tests them with the built-in decoders. Whatever can be read as CW, RTTY, PSK31/63, QPSK31 or APRS is identified as such and decoded straight away.
Open in the browser
No installation, no sign-up needed.
What the page does
- Waterfall with frequency scale and markers
- Several signals at once, e.g. CW and RTTY side by side
- Parameters per signal: frequency, shift, baud rate, speed
- Unkeyed tones are identified as carriers
- Live: continuously the last eight seconds
- With a connected radio: RF frequency per signal and tuning at the press of a button
Background
It is based on a Fourier transform with a Hann window. Peaks clearly above the average noise are tested as candidates: two peaks 170, 425 or 850 Hz apart suggest RTTY, a narrow keyed peak CW, energy at 1200 and 2200 Hz APRS. A mode only counts as identified when it can actually be decoded.
In practice
How it works: load a recording or connect the receiver output and start the signal search. Bright lines in the waterfall are signals; the table below lists frequency, width and identified mode for each. With these values you can then examine the signal in more detail in the matching decoder. For good results the signal should stand clearly above the noise.
Frequently asked questions
Which modes are identified?
Currently CW, RTTY, PSK31/63, QPSK31 and APRS. Other signals appear as “unknown” with frequency and width.
Can I upload my own recording?
Yes, WAV or MP3 up to 2 minutes. The file stays in the browser.