Strange signal on 5174 kHz

[Freqs]

Hi All, my first post so I apologize if this is the in the wrong spot...

My friend in Minneapolis MN came across this and he can hear it day or night, I live in central Wisconsin and only heard it at night.
For me this was 02-Feb-2017 around 0300Z, but was pretty much anytime after sunset in to the evening. Probably be there this evening too.

Attached a screen shot and mp3 audio, the audio is really low so the volume might have to get cranked It's very cyclic and seems to recycle every 16 pulses.

Thanks!

[Freqs]

It's on right now as of 22:45z

I tune to 5174 kHz but from the waterfall it's just over 2kHz wide

[Token]

This is LINK-11 CLEW, also called TADIL, MIL-STD 188-203-1A, and STANAG 5511.

Link 11 is a tactical data link used by NATO forces (mostly naval, including USCG and US Navy) that allows multiple platforms to share situational awareness.  For example one ship in a task group can have its radar active and tracking targets, and all of the ships in that task group can have the same track data without using their own radars.

Link-11 can unencrypted, but to be honest I don't think I have ever seen any that was.  In the military when we used Link 11 without encryption we called it Link 1, this is technically incorrect because Link 1 is actually something else, but it is what we called it anyway.

This could also be Link 22 as -22 is replacing -11, however I don't know how to tell them apart and there may be no way to tell them apart as -22 is supposed to be backwards compatible.

T!