In article ,
Greg wrote:
That strange noise is on 3.994 at 2:10Z.

Try listening to RCI's DRM transmission on 9800 kHz from
21:00 to 00:00 UTC and see if it sounds the same.

As I understand COFDM, it's a whole bunch of phase shift
keyed carriers only a few 10s of Hz apart, so when you
listen on SSB, they beat together and you get this strange
roar with ascending and decending tones in the background.

Mark Zenier Washington State resident