I sometimes get this type of QRN (mistake in title, got Q codes mixed) very strong, video in link is example of such instance where sometimes even Noise blanker on highest settings barely masks it. It sometimes falls on several portions of band. I think it sometimes just "disappears" until I notice it again, but can't be sure. the way it moves makes me think the receiver is being overloaded with AM harmonic? not sure if anyone can help appreciate it.