I have been closely tracking frequency usage (or lack of) in the 225-400 MHz milair band for years. When I first started doing this as a young Monitoring Times columnist, I coined the term "spectrum hole."
The 225-400 MHz band frequencies are normally spaced at 25 kHz intervals (except in the milsat subbands). Any lack of activity either reported, listed in official DoD pubs, etc. on any UHF milair freq will result in that freq being listed on my UHF Milair Spectrum Hole list (see our exclusive page at http://mt-milcom.blogspot.com/p/uhf-225-380-mhz-milcom-spectrum-holes.html).
Our close friend Jack Nesmith down in Central Florida yesterday identified some new
activity on one of those spectrum hole frequencies in my list.
277.775 MHz was active with Bolt-43 calling Lightning Ops (6AMW Command Post at MacDill AFB). Normally Lightning Ops uses 311.000 MHz so this would be a new frequency for that Command Post. Maybe this new one was up for the POTUS visit.
At any rate thanks Jack for passing that one along and if you hear any confirmed activity on any of my spectrum holes, please drop me some email at the address in the masthead. I look forward to hearing from you.