It's not digital, it's a frequency hopping technique so you would only get a few words before another station would use the same frequency, meanwhile the original has pushed off elsewhere. All controlled by a separate encrypted digital frequency that all the radios listen to, to keep in sync. All very clever so they can use current radio technology with a slight modification. So anyone listening would get a cacophony of short transmittions, certainly not enough to follow the thread of a conversation.
You are quite right, although the military use a slightly different system called spread spectrum where the signal is digitised and each packet is is sent on a different frequency using a wide band, which to anyone listening would be totally random unless you were sync with each transceiver. Listening on a normal receiver you would never know there was a transmission there, all you would apparently hear would be an occasional click or buzz which you would put down to interference. It makes it very difficult to jam using Electronic Counter Measures, because if you try you end up blocking your own communications :D
There is an interesting article somewhere about it, I might have it still in my Bookmarks, otherwise I'll see if I can find it.
Early FM days: Police at one end of the domestic spectrum- A gem I heard was a (then PCW) asking for assistance. She was in Oldmarket (nearby city) and the "gear lever thing had come off in her hand". Mobiles: There seemed to be a host of disloyal husbands phoning to say they would be late home and then almost without pause ringing their paramour to arrange their hotel. Business magnates discussing what to do about junior staff or busines deals that day!
Civilian AT control still provides some interest from time to time. Long past memory of a crude airband set - A quote on a company frequency (definately not for cabin ears) "- with all the snags we have, if we ever get in to Gibralter we'll never get out again!"
There are others from the past but I'd better keep those to myself.