The other night I was listening to 11175 and heard a male voice come up several times with a 10 count and identified as "Andrews". I know that it means Andrews AFB. About 5min later , the same voice came up on 11175 and all the others with a very long message with a different call sign.
My question is, does the call sign change based on who the message originated on? Will Andrews use different call signs for different originators if that makes sense.
Keep in mind the specifics of this network are sensitive information. That means getting confirmation of things is hard. Read, hobbyist guess at a lot of things, and sometimes piece together various chunks of open source material to try and paint the picture of what is going on. There is a lot of information out there on this network, some of it good, some of it bad, and some of it very outdated.
Regardless, the basic configuration is a control and audio network connecting multiple transmitter locations around the World. Multiple command centers have the ability to assume control of the network. It appears that, most commonly the control station is located, physically, at Andrews AFB. The control center can transmit from any, or all, transmitter locations and frequencies simultaneously.
So, my guess:
The "different" callsign you heard is the rotating daily callsign, some sources call this a tactical callsign, but I have no idea what the correct term for it is. This is a callsign that is used for most group calls or network control calls, and changes every 24 hours, at 0000 UTC daily. Whoever is controlling the network uses this call, as the control station, and recipients recognize that this callsign means the information is coming from the command authority. There is no rhyme or reason to the specifics of these calls, in the past they were picked in advance from a pre-approved list, I assume they are computer generated these days. Notice the calls are 2 or 3 syllables, they may be one or more words to make up those syllables. "Cotter Pin", "Palm Leaf", "Gunrack", "Dedicate", etc. Periodically, often years later, these callsigns get re-used, I assume the list of approved callsigns is not infinite.
The "Andrews" callsign is from one of the individual nodes or sources on the network, in this case, Andrews AFB. Using this callsign indicates to whoever hears it that the transmission is not meant for the general group, or not meant as coming from the command authority.
I assume that for testing (or other) purposes whoever is the command authority (command center?) has full ability to control the individual transmitter sites. If they want to test a specific transmitter node, say the 4724 kHz transmitter on the West Coast, they can select that transmitter and do a test with only that freq and hardware.
In the past the "long messages" used to be sent using other IDs, "Mainsail" was one, or you might hear the long message from "Andrews", "Offutt", etc. My assumption at the time was that the command center currently in control IDed itself as such, but several years back they shifted to the rotating callsigns regardless of the source location.
And yes, you can hear the obvious same operator voices identify as Andrews (sometimes other locations) or the current daily callsign. Speaking as the control center / node they would use the rotating callsign, speaking in other capacities they would use Andrews.
T!
