Once you've heard the warble of SSTV, it is quite simple to recognize - I hear it all the time around 3850 and 7175kHz or so; this is in IARU R1. Other regions

Once you've heard the warble of SSTV, it is quite simple to recognize - I hear it all the time around 3850 and 7175kHz or so; this is in IARU R1. Other regions may have other activity centres.