I just happened across some digital stuff on 13,830khz while listening in the car (Icom IC706 + hamstick). On AM it sounded like a random three tone generator but on USB it was clearly digital. The nearest building was a block away, nearest house (farm house) twice that, however I was parked right next to some power lines than ran along the biking path. As I drove away, sigs dropped from S9+ to gone. FWIW