The Days Are Just Packed
DIre Wolf is a great implementation of old, slow protocol. I like it a lot. It runs very well on a Pi 2B and is very reliable. I am about to dig into why it doesn't support hamlib on Windows. SoundModem doesn't either so someone wrote a virtual device driver for Icom radios that creates a software serial port so the program can assert DTR and have it turned into a CAT command. Kudos for ingenuity but that's not going anywhere near my computer. But using the Pi as a network connected TNC with Winlink Express works quite well. Not so for Pat, unfortunately, which depends on the fragile Linux AX.25 implementation that DARC is getting paid to fix (although that project seems to be enveloped in darkness). I've been looking at the Go code for Pat, and how I might take a crack at adding AGWPE support for Direwolf. One of my local club members has offered to assist, and he does Go for a living. Unfortunately he has a high pressure job and a new family, so that assistance will be mostly advisory.
Speaking of ARDC, they seem remarkably opaque. They don't publish details about the projects or why they were selected. It's not like the security of the nation will be compromised if this information gets out somehow. They seem to have as much money as all other amateur radio organizations combined.
The DMR guys have lots of 5 GHz links using COTS radios, routers and switches. Most of them have an extra port. But getting 6 meter antennas and equipment on the towers might be difficult. Many radio sites won't accept amateur equipment because it doesn't pass the "lightning test," the RFI test, etc. Motorola low band equipment might be modifiable, but then you run into the problem of trying to track down spare parts.
If we're starting with a blank sheet protocol, it would be nice to include T/R frequency and geolocation data (6 character maidenhead grid square would probably be sufficient) so that user nodes could have the option of QSY on the fly without having to manually retune and re-establish. In other words, a roaming protocol but with the radio having some say in the handoff. While we're dreaming, signal quality feedback when in a duplex QSO from the receiver so the radio might increase power or try another node.