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TARPN Features

This document describes the TARPN packet radio network design as of October 24, 2017 with some minor corrections added January 2020. 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.
TARPN is not a club.
There are no dues.

TARPN creates a network which thrives when fully saturated. Most packet radio systems require sparsely occupied channels, i.e. the channel is mostly quiet. In a sparse network, the network suffers failures and disconnections if there are more than two conversations on the channel at a time and the total channel occupancy exceeds 20%. The TARPN can survive full occupancy indefinitely.

TARPNs specifically stay away from dependency or burden from Internet and other commercial networks. The whole point of the TARPN is to show what we can do without Internet.

TARPN philosophy

There are a couple of goals which are not contradictory. 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:

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 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 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.

© Tadd Torborg, 2014↝2022 -- all rights reserved