You could also look in your state forum and see if the system is being discussed there.
Also take a look at the FCC licensing, to see who, in your area, is licensed for that frequency. Quite often, for some business band related frequencies, there are multiple licensees in my county, often a half dozen. You can look at the licenses, and see who, whether one, or several, is licensed to use the NXDN emission codes. That's not always helpful, as I often see users, especially businesses, using an emission code (like NXDN or DMR) that is not authorized on their license. They are licensed for that frequency, but only for analog (sometimes digital) channels.
ou need to keep listening for identifying info such as specific schools, streets, etc. Do your own research and determine what transportation company serves said schools (if not their own district's buses) and after you're confident you've nailed it down, make the DB submission
What I do is set the scanner to record all of the activity on the frequency (or frequencies) in question. Then, download to my laptop & use the
scanner audio player to sort them by frequency, as well as by time, to see if I can get enough pieces of a conversation to nail it down, or at least narrow the possibilities. You can sort them in a spreadsheet type format. I run
NTIRN (a local area wide system) in ID Search, because we're still seeing new talkgroups, sometimes one at a time, sometimes more, as current users add another talkgroup, or a new agency switches to the system.
Also, if also logging with ProScan (or ARC536 Pro), look at the user (radio) ID's collected from transmissions. If you see the same UID appearing both in your "new, unknown" frequency, but also in one that
is in the database, they likely are connected in some manner.