P25 Roaming and affiliation - Answer to a puzzle

[alan22]

If you are habitually monitoring a particular P25 site you may start suddenly hearing transmissions from another distant area. Most puzzling! For example, I am in Port Stephens and every now and then at holiday times I start hearing Sydney NSWFR.

The reason for that is that one or more mobiles from Sydney (perhaps senior officer(s) on holiday here) have their receivers on and these automatically affiliate with the local site (Gan Gan) and are now automatically set to roam (roam can be settable manually too). Now everything on that Sydney talkgroup is on Gan Gan, which usually only bears local stuff, such as Newcastle NSWFR.

[railscan]

That is one possibility. Another is that FRNSW patch various talkgroups together so that one operator maybe controlling three districts or regions. If they are patched properly, then what is said on one talkgroup is re-transmitted on the others. One day you maybe listening to Sydney, the next it could be Broken Hill. There appears to be no rhyme nor reason to FRNSW patching.

R

[alan22]

FRNSW have a code. If an operator announces 'test' it is a signal for another controller to take over.

[VK3RX]

In ATC we said "Help!!!"

Not on the air though .......

[alan22]

Takeover in a another location, of course... to wit, for example, Sydney to Northern...