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TARPN Features

This document describes the TARPN packet radio network design as of June 2, 2017. This design is subject to change because the contributor base is growing and we're all learning.

TARPN is a description of nodes, of a network, and of a design philosophy tailored to make the network presentable to the ham radio operators of today.

TARPN philosophy

We wanted to build the largest Amateur Radio packet network we could. To do that we tried to come up with an optimum of several factors: I would not have gotten involved with the project until the system looked like it could be done with a modicum of all of these factors.

TARPN network

TARPN node features

The packet station consists of a Raspberry PI running Debian Linux and with one or more TNCs. The Raspberry PI boots from a slow solid state SD card. It is totally silent and runs very cool. The PI supports Ethernet, HDMI output, and has a built in hub providing two or four external USB sockets. A keyboard and mouse could be attached. A USB hub could be attached.

WiFi is included if the Raspberry PI 3 is used, else there are many WiFi adapters supported for the older Raspberry PIs.

The software load provided by the TARPN install scripts (see Builders section on this web site) include these features:

It is trivial to run a BBS on a desktop computer and link it in using G8BPQ. Using such a BBS it would be possible to accept many connections. Support for such a BBS is beyond the scope of this web page. BBS operation is supported on the PI itself as well. If somebody would like to take this on as a project, I would love to document the process. -- KA2DEW

TNCs and Radios -- Making Links

After installing the OS, utilities, applications and the TARPN scripts on the Raspberry PI, you are ready to start hooking up radios.

Each TNC-PI may be wired to a single radio which can establish a link to some other TARPN node.
When establishing frequencies and bands you must make sure that one of your radios in transmit will not block the reception of a packet by another of your radios.

A suggested TARPN node site would have 3 radios, one each on 51, 145, and 440Mhz. You can acquire an antenna like the Comet GP-15, and three commercial radios, like the Vertex FTL-1011, Kenwood TK760H, and Kenwood TK805D, three TNC-PI daughter cards, and a Diamond MX-2000 Triplexer. With 100' of LMR400 coax cable and several connectors you can build an entire three port node for about $700, not including cabinetry, antenna mounts, lightning protection, power supplies and batteries.

Using the 3 port TARPN node described above you can now make links to neighbor nodes and begin building a network. Your 51Mhz Vertex can talk 20 miles through forest to another same kind of radio. 440Mhz radios have much shorter range. If you are lucky enough to have a tall structure or view-home to work from, you can get much longer range out of 440Mhz.

Continuous Up Operation

Some packet radio users consider that packet is cheap because the only piece of equipment required to make it work is a TNC. Radios are free because the hams already have them. A $700 TARPN station will therefore seem to be really expensive. It is hard to argue with that logic. If the stations involved are complacent with having packet radio only intermittently available, and to having inconsistant results when they try to use it, then TARPN may not be for them.
The interesting thing about packet radio networking, as separate from infrequent guest operation, is that each participant's station becomes part of the network and is a service to the other hams. Not only do other stations get enjoyment from using the paths each has created, but each builder becomes part of an emergency system, a step above being merely prepared. They also get to learn how to, and gain experience from, keeping a resource on-line indefinitely, a wholly different regimen from whipping out their HT on the way to work.
© Tadd Torborg, 2014↝2017 -- all rights reserved