UNID 6942.6 USB 0041 UTC 11 Dec 2013

[OldSeaRock]

Hell of a noise - don't know what it is.   S-9 at peaks in Tejas.

dit-dit-dit-dit-dit-dit (NOISE after 6 dits)

00:44 UTC  and now it sounds like there are two of them.

00:48 - now it's eight dits before a noise.

[rdla4]

Link 11 Tactical data link. This thing will show up and spend <sometimes> days on the same frequency. It usually likes to park at 6945-6950.

[Token]

Actual tuned frequency is 6942.0 kHz, tonight it is USB only, but it can also be LSB or even ISB, different data on LSB and USB.  When properly tuned the Doppler Tone (lowest tone) is at 605 Hz and the Synchronization Tone (highest tone) is at 2915 Hz.  You will note the rhythm changing as different units enter the net and as different data is sent, suffice to say it does not always sound the same.

This pops up in the band often, and might be found on any frequency at all.  Typically it is below 14 MHz when on HF and is also found in UHF.  An older thread with a description of what Link 11 is can be found here:
http://www.hfunderground.com/board/index.php/topic,12731.0.html

T!

[OldSeaRock]

Thanks for the ID.  Link 11.  I'll check out the info.