I had stepped away from this investigation a while ago and this evening been reading the work done since then.
The question I started with was based on the news that the UA seems to broadcast its current location relative to the nearest celestial body.
"Why might it be significant for a UA to broadcast where it currently is? What use would it be?"
The next thing I found interesting was that only 3 UA's seem to be known about in game at any time? Is this the case?
Could it be that an individual UA and its broadcast is not significant on its own. Might there be some value in knowing where ALL UA's are? Could there be a significance that knowing the current location of each UA relative to others provides a signal to a single point triangulated by ALL known UA's current positions.
Think of it as a message along the lines of:
UA 1 - I am here, which puts me this far from position XYZ
UA 2 - I am here, which puts me this far from position XYZ
UA 3 - I am here, which puts me this far from position XYZ
Result, a location of a 4th point/location that is triangulated from the information provided ALL known UA's, their current location and some other data that has yet to be decoded?
I have no UA, no knowledge of how to decode the sounds, or any proof. I did play a game as a kid using CB radios and signal strength to triangulate a 'target' that was broadcasting from an unknown position. Maybe the US's are doing a similar triangulation?
I didn't read anything that suggests this has been looked at, but it sounds feasible within the game.