I would not count on using what talkgroups a new one is near to determine who is the user of an unidentified one. It is true that many are located together. There are gaps in that logic.
Take a look at Summit 800 sorted
in List All mode.
You'll see that Valley, Penninsula, and Norton all have their talkgroups together. That is not the same for Green, New Franklin, and Tallmadge. Those three communities are intermixed.
My best advise would be patience. Listen for familiar voices. Listen for conversations to move to and from the unidentified channel.
Use software (unitrunker, etc) that can track what radios are using what talkgroups. That might give an indication, but is not the true answer. A hiccup in reception could cause a slight change in the decoding. Plus, many communities have each others talkgroups. Springfield Twp has some APD talkgroups, for example.
