Some modes are very easy to identify by eye or because of the frequency, or by sound. I'm wondering if there might be a piece of software someone has written that would let you define a passband and it tells you what kind of signals are there. What prompted this was listening on the 10m FT8 frequency and hearing a very faint tone - noise was high enough that I couldn't tell if there was a FSK-type warble. There were no other signals on 10m in the CW/data area. Checking the waterfall, sure enough there was a trace that was on for just under a minute, off for a minute etc. I switched WSJT-X to the JT9+JT65 mode - no decode. I switched to the 60 second cycle of FST4 - nope. Of course it could have been a ham that was just "tuning" without any modulation, and that for 5 minutes straight kept repeating this specific pattern... but the simplest explanation is that it was a mode that is not in WSJT-X. Right? OR for some reason I could hear the sound faintly and easily see the trace on the waterfall, but it was not strong enough for a decode...? Sounds unlikely ... I guess I could install something like FLdigi and use trial and error... Is there an automatic digital mode detector?