I am looking into the possibility of building out a small packet network
in Vermont, using VHF and UHF links between simple ham-owned home nodes
for real-time chat communications. No commercial sites, no fancy
infrastructure, just simple, inexpensive fun.
North Carolina has built a very successful network on this basis, using
a $35 Raspberry Pi as the node computer and $45 TNC Pis as the node
controllers. The key requirement is dedicated links between nodes on
different frequencies, which avoids the packet collision and persistence
problem. If you have three nodes A, B, and C, you would have a link
from A to B on one frequency, and a separate link from B to C on a
different frequency (probably on a different band; 6, 2, and 70 cm all
work, and 10 is a possibility).
1200 baud may sound slow, until you realize that PSK31 was a very
successful chatting mode at /31 baud/. Packet seemed slow not because
of the 1200 baud limitation, but because of all the collisions and
retries. The dedicated links fix that problem.
Unlike Winlink and the old national packet network, we would NOT connect
this to the Internet. That would just swamp the packet network with
garbage it can't handle, much of which has nothing to do with ham radio.
More information here on the North Carolina team's great success with
this type of network:
http://tarpn.net/t/packet_radio_networking.html
Here's what you would need to build at each node:
http://tarpn.net/t/builder/builders_node_shopping_list.html
I've already had a phone chat with Tadd, the lead on the North Carolina
TARPN network. He's enthused about helping us get started.
Is anyone interested in working on this with me?
73,
Cathy N5WVR
