screen shot is as follows :-
you make of that.
grunge at 512 KHz is the SDR local osc.
A Navtex transmission just started up at
2100utc on 518 KHz but quite weak, but there are much stronger images at 514.5
& 513 KHz & a very strong steady signal at 516.35 KHz with lots of
spurious signals down to about 498.500 KHz.
Transmission ended at 2109utc.
I will upload the screen shot to my web
Gary - G4WGT - IO83QP.