/diy/ - Do It Yourself

>>1453210
Grab a copy of the FCC's spectrum allocation chart. That'll tell you what's where.
Also grab a copy of the ARRL ham radio band plan. Again, tells you what's where for amateur radio.

The "encoded" stuff you're hearing is likely digital.
In the US, public safety is P25 (and usually 800MHz band).
Commercial stuff is moving to DMR. Real irritating buzzing noise (2-slot TDMA).

Public safety inteorp is mostly analog (VFIRE21, VSAR16, UCALL40, 8CALL90, etc) but those aren't used for day-to-day operations.
Might find some FMN simulcasts, smaller towns may still be using analog equipment.

Same for business, there may still be some analog stuff around.

Amateur voice is mostly FM in the VHF/UHF bands. Occasional Fusion/DMR/DSTAR channels in there.

Air band is often AM.

Each group has its own lingo.
"10-4" is pretty well known, i think everyone understands that one.
"I'm code 4" on a public safety channel might mean "everything's fine i'm back in service".
Hospitals/med use "color codes" - code blue, code black, code yellow, etc. Loosely standardized.
Commercial will come up with their own things.
Amateurs use 3-letter Q-codes. Short-hand for relaying info on morse code, occasionally makes its way into voice modes.