There are 8 uhf channels licensed at the CBC site, although last time I was there only 4 were on air.
Yeah, if you look at those licenses, the "unused" channels are all adjacent to the in-use ones. I am wondering if they're licensed simply to guard the existing channels from interference.
409.1625 was on for a while yesterday/today as NXDN48 system 2021. That freq was LCN 11; DSD+ said "CC moving to ch 12", and I see activity on 409.4125, but DSD+ will not decode it. Could be because I'm too far from the site, though.
I believe I heard some "test test test" chatter on some of these four freqs yesterday, in NXDN of course.