When I was in the military (you have been reading all these blog posts?) so you will know. I uset to use a handheld RTTY of sorts. It ran at a super low baud rate taking 4 minutes to send a whole sitrep. Yes, I used to compose sitreps. and get them signed off and then sent. You had to write them up, type them in and send them. On the other end you just printed them off. The transmission was FSK and worked over a VHF radio if I remember. Anything from 25 to 100 watts, although the smaller portable radios could hold the carrier for long enough to send a short message too. Portable radios were good for practice, but never managed to keep going from long enough; pretty much because they were designed for voice and not being continously held with the key down. To hear what they might have sounded like if you happened to be on the same channel.
You might recognise these noises from some popular naval criminal investigative TV series intros.
Additional sources to look into crediting and getting copy permission:
Cambridge Lean Coffee
3 days ago