[Lowfer] Can anyone ID this UNID signal ??

[Andy - KU4XR]

I saw the signal until around 5 am ( 10 UTC ) when it faded into
the noise and never reappeared. I was looking for Joe - VX9MRC
last night in QRSS-3, and this signal was showing up at 507.771.2 KHz..
It is repetitive, but I have no idea at all what it is. The time ticks
in Spectran show the TX to be 4 minutes with a 1 min. 10 sec. space...
I normally just accept random stuff as just that; Random... But this
one was all night long, and as mentioned; repetitive in nature.. 
Can anyone ID the mode by looking at it ?? 
It's not a big deal, I'm just curious about what it is ..

Thanks and 73 to all:

Andy - KU4XR 
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