Excellent capture, Ray. Definitely not Opera, though, which would look more like QRSS in that it's only a single frequency tone that's keyed on and off. While the coding scheme is very different from Morse, it is the time intervals that the carrier is off versus on that carry the information being transmitted, just like Morse and QRSS; aka ASK (Amplitude Shift Keying?) to Opera afficionados, or OOK (on-off keying) to us mere mortals.The modulation method you have captured is best described as MFSK (Multitone Frequency Shift Keying), or sometimes as nFSK, where n will be an integer indicating the actual number of frequencies employed by the mode in question. The carrier is on continuously for the entire duration of the message, but its frequency is stepped between certain discrete values. The message elements may be encoded in either the particular step that is landed upon, or in the frequency difference between successive steps, depending on the message protocol. Nearly all WSJT modes are MFSK modulation methods, as are JASON, Piccolo, and a few others whose names don't readily spring to mind.
The signal you have spotted is an 8-level code, unless my decrepit old eyes are miscounting the steps. The step transitions appear to be Gaussian filtered for spectrum efficiency, making it an 8-GFSK or maybe 9-GFSK modulation scheme, and the total bandwidth of all steps occupies only a little over 0.5 Hz, with a 900 second T/R sequence. Just at a first glance, it appears to be a beacon mode designed especially for LF, because it would be totally useless with the kind of Doppler shifts commonly experienced even at mid-MF.
Unfortunately, I am not sufficiently up-to-date on my WSJT modes to suggest one to try. It may even be a new one under development, but since I am personna non grata at the WSJT io group after unknowingly wandering into forbidden territory involving what appears to be a long running battle of some sort,* I am not privy to what may be under development any more.
John
* [BEGIN SLIGHTLY O.T. RANT] I foolishly was curious how US hams are dealing with the 10-minute station ID regulations of &sec;97.119 when using modes with longer T/R sequences like 15 or 30 minutes on 2200 and 630 m. Plain WSPR-2 has provision to do a CW ID after its mere two-minute sequence if so desired, even though such is not required at all (the code specs being published and decoders freely available that're capable of doing the job in a single transmission slot, or two at the most, with time to spare). So, I was hoping to learn that some similar provision had been made whereby a user could elect to insert a CW ID during a non-critical point in the sequence. Or, had the guys already using the long modes come up with an alternate workaround of their own?
Well, the first reactions I got were "What 10-minute requirement?" This was a natural enough reaction, I suppose, from hams in the UK, Canada, Australia, and lots of other places which have rules that are a lot less nit-picky or not nearly so strict on ID timing as our FCC is. Most administrations in the Free World appear to be a lot more flexible, and some even seemed to have slower transmission modes in mind when they wrote their rules. What I found more worrisome was when I got push-back from US hams, some of whom apparently did not know we have ID requirements (???) and some who clearly did know but hinted darkly that I shouldn't rock the boat and spoil everybody else's fun.
What boat? Which fun? Goodness.
I tried one more time, again being very collegial in trying to explain that I figured there must be a simple fix of some sort, mentioning in passing that my only interest was in getting on the air with one of the newer modes while protecting the Extra Class license I had just worked so hard to get.
That evidently tripped somebody's mental circuit breaker! Next thing I know, my post is gone. In its place was a decree from the group administrator saying that the thread was closed and the topic was non-productive, and hinting that such had happened before...while in my email inbox lay a steaming pile of BITPFWAC,B {ask me offline, or ask Chuck Lorre} from the topic moderator, stating his imperious opinion that I was accusing other hams "without any evidence" of violating the terms of their licenses, so my every post from thenceforth would be moderated most strenuously, etc. etc. Now, seems to me if I had presented WSPRnet captures showing the timing and call letters of stations involved (ie, "evidence"), that would have been accusatory, which totally was not my point.
So no, Mr Petty Functionary With The Clipboard, I'll just remain ignorant I guess. [END RANT MODE}