[Lowfer] 12.450 KHz Data Signal

[Dexter McIntyre W4DEX]

Just recorded this morning is a data type signal that I also heard years ago 
when KD4RLD was xmitting on 9 KHz while I was receiving.  It may be something 
local or an image signal but I have heard it on two different receive setups.

I've seen no pattern to the time period between the short transmissions. 
Sometimes it may be way over ten minutes between signal bursts and at other 
times there will be two bursts in succession like in this recording:

http://www.w4dex.com/vlf/12450hz_data.wav

Dex