Terminal Node Controller - An ORS Build Project
Mark introduced (again) Terminal Node Controllers (TNC) at the Aug 9 Saturday morning class. A few
attendees were interested in Packet Radio. Packet Radio is the communication of messages that may
include environmental parameters like temperature, altitude, other sensory input, and a longitudelatitude (GPS) position.
Three major types of digital transmission are available: Audio and Frequency and Phase Shift Keying.
Audio shift keying use two tones to represent the digital '1' and '0' data. These transmission can be
heard - hence the audio. TNCs for audio shifting can be plugged into the earphone and microphone
jacks of a radio.
Frequency and Phase shifts are a different matter. They require a special port on the radio for their input
and output. Most HT's don't have this port.
There are several protocols (format definitions) for packet data. One is the AX.25 format that is used by
the Automatic Packet Repeating System (APRS) and others. The TNC is a microcomputer controlled,
modem interface that marries a radio to a computer. A simple TNC just converts received audio radio
messages to data and collected data to audio for transmission. A computer is needed to actually read the
data from a TNC and present it as the sensory input, location, or messages that are contained within.
Another type of TNC has to be used for the phase and frequency shifted transmissions, like PSK31.
With the new single board compupters (SBC) like the Raspberry Pi and the Beagle Bone, a portable
packet radio system can be made that allows keyboard input and data display..
A suggestion was also made to have a build session where the TNC would be purchased as a kit and put
together. I am offering a build get-together for the TNC. Please contact Gary [email protected] if
you're interested. We will put the kits together and get them working.
Here are the TNCs that are being considered. The first two are available in both, kit and wired, versions
and the last two are kits only.. All of the TNCs need to have a radio connection cable, most of them
custom made.
Coastal Chip Works (John Hansen)
www.tnc-x.com
The TNC-X uses a MicroChip Pic uC. This box is available in a plain TNC version but can be modified
with easy-to-build and add Daugther boards for digipeating or to communicate via BlueTooth and
USB. The Blue Tooth allows APRS monitoring on an Android phone. The interface is a DB-9
connector for the computer (or USB, if purchased) and a DIN 5 pin for radios. It does need a cusotm
radio cable. Get the 5 pin DIN plug to make a cable. When not connected to the computer via USB, a
power supply or 9-volt battery is needed.
Also, an SBC version plugs into the Raspberry Pi (www.tnc-x.com/TNCPi.htm $40) - just add a video
adapter from www.adafruit.com ($35) to have a complete, portable APRS system! It can even run
XASTIR (a mapping, tracking, messaging, weather, weather alerts, and Search & Rescue system)!
Another SBC version is the Beagle Bone Black TNC (www.tnc-x.com/TNCBlack.htm $43). For both
of these mini-computers, the computer connections are made via the boards, themselves (no cables). A
radio cable is still necessary.
Parts
$ 88
2
6
$ 96
TNC-X with USB daughter and a case
One 5 pin DIN plug to make custom cable
Shipping (or $10 for the extras, below)
Total
Extras
$ 17 X-Track (stand alone operation - needs a computer)
25 Blue Tooth daugther board
20 Digipeater daughter board
TinyTrak4
www.byonics.com
This is a small device with a sexy blue case. It uses an AtMega uC. It is great for hand held portable
use. The computer and peripheral interfaces are DB-9 connectors which are much easier to make
connections. It has built-in digipeater and temperature monitor - no extra hardware needed!
The features are: TNC; APRS Digipeating (with add-on); DSP either 1200 or 9600 baud; sensor
processing; and upgradability. Note: The package, below, includes a display and USB connector.
Parts
$ 65
34
20
15
6
$140
TinyTrak4 Kit (add $10 for built version)
Display with adapter (stand alone operation)
USB connector (computer connection) NOT Win8 Try (www.sparkfun.com/products/11304)
Serial Splitter (for display, GPS, keyboard, etc)
Shipping
Total
Extras
69 GPS or +$10 for higher altitude GPS
Radio cable (TNC to radio connection)
Yaesu M12 or M96; Baofeng - make one
Kantronics
www.kantronics.com
Great description of TNCs at www.kantronics.com/modems.html
This is a robust device larger than the TinyTrak4 with a Motorola uC. It is not a kit. Check out the web
site for more information. The specifications are a bit nebulous to read but this is almost a computer
terminal - no display though. It has a DB-9 connector for radios and DB-25 for computers. The
connection to 'modern' computers would require a DB-25 to DB-9 converter with a 'smart' USB cable.
See www.sparkfun.com/products/11304
Parts
$200 KPC3+ TNC comes with connection hardware
Shipping free from HRO (www.hamradio.com)
Rascal Kit $49 + cable + USB to COM Port
2 diodes, 2 transistors, 2 resistors, 2 minature 1:1 transformers, 2 coupling capacitors, 1 varible
pot, 1 5 pin DIN jack. Other attachments to the PCB are the serial comport, and sound card I/O
cables.
Cables, Connectors, Components, Case, Printed Circuit board, PSK31 software, pictorial diagrams,
schematics, software CD and setup instructions.
http://www.packetradio.com/catalog/index.php?main_page=product_info&cPath=26&products_id=166
This PSK31 kit uses the PC sound card. The frequency to connect is 14.08 MHz (an HF freq). It
requires a data (not audio) connection to a radio - usually not a hand held.
TNCs for PSK31
These TNCs, phase shift interpreters, will not substitute for the audio shift devices, above, for use with
APRS. These are 'modems' that convert the shifted data to audio. They both must have a computer to
workd the data into messages. We will have to build radio cables. Both companies are in the USA.
Manuals are available online.
Altoids Tin version ($55)
http://kk7uq.com/html/model_ii.htm
I have plenty of the Altoids Tins. This will also work for SSTV. This provides for isolation from the
radio and computer and some comtrols. Plus, there is a 'speaker' to help tune.
Radio to Sound card interface () $25 + S&H
SCI-6 PC Sound Card Interface Kit
PSK31, RTTY, WSJT, Echolink and other exciting digital modes. The SCI-6 interface is your ticket to
these cutting edge developments.