[Spooks] Buzzing Digital on 3300 KHz?

[KD7JYK DM09]

I am in Nevada.  What is the buzzing digital signal that can be heard on 
3300 KHz?  I have been hearing it from 0400 to 0430 UTC.  Multiple carriers 
that stop occasionally, then the spacing between them changes, 50 Hz, 100 
Hz, 150 Hz, et cetera.

As I type this, the signal stopped for several tens of seconds, then a very 
fast and very, very wide pulsating signal has taken it's place.

Possible Superdarn system?

Kurt