[Lowfer] strange VLF transmission

[ToddRoberts2001 at aol.com]

Hi Garry and Doug,
I have wondered about the significance of 17.8KHz for Tacamo and
read that 17.8KHz was the original frequency for NAA which has since
moved to 24.0KHz. I understand that 17.8KHz is reserved now for 
different locations in the U.S. meaning portable or mobile  operations.
I have also read that TACAMO has been observed sending 
transmissions as short as 20 seconds in the past.
73 - Todd WD4NGG
 
 
 
In a message dated 2/15/2012 8:42:05 A.M. Eastern Standard Time,  
k3siw at sbcglobal.net writes:

Doug, I wonder how precise the center frequency of 18 kHz was? 17.8 kHz  
is a frequency where I've often heard wideband TACAMO transmissions.  
They often (always?) begin with a burst of 50 baud RTTY, then send wide  
and very wide signals with short off-time gaps in-between. I don't  
recall those transmissions being as short as 20 seconds but I suppose  
they could be.