3 ms·

Almost certainly Packet Radio: https://en.wikipedia.org/wiki/Packet_radio https://en.wikipedia.org/wiki/Packet_radio, probably on the amateur band: https://en.w

• switchbak 11y ago
  This is actually surprisingly novel, and especially impressive given the developer was in high school at the time. Running ethernet to these locations can be challenging, and often an SMS based approach or mesh network is used instead - which is really not that far off from this approach (with some obvious benefits).
• nickpsecurity 11y ago
  Thanks! I knew they used something but nobody ever told me what the old standards were. I'm adding it to my link farm as some call it. Bet I find a use for it, too. :)
• kw71 11y ago
  This application should not be allowed in Amateur Radio service, because it's being used as part of a business or government operation. The piece of spectrum this system actually uses, since it is shared with their maintenance radio fleet, is definitely not part of any amateur service allocation ("band") The term 'packet radio' also implies (to me anyway) certain kinds of applications and messages, which don't apply to a system like this. Anyway, if there was some kind of IP or other routable protocol on the air here, that would be overdoing it. The messages probably look more like what you'd find on a multidrop serial bus, with elements including source and destination address, length, payload, checksum. A bunch of FSK modems working on the same radio channel is not much different to a multidrop serial bus.