<div dir="ltr">I saw an old AX.25 TNC ad the shop. I don't know if it works.<div><br></div><div>I had an AX.25 node setup. That mode is pretty dead in this area. </div><div><br></div><div>TCP/IP doesn't work very well over it. It's an old protocol and they are almost opposites in their technical approach.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 21, 2016 at 6:46 PM, Kris Kirby <span dir="ltr"><<a href="mailto:kris@catonic.us" target="_blank">kris@catonic.us</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On Mon, 21 Mar 2016, Jeff Cotten wrote:<br>
> This looks awesome, I want one.<br>
><br>
> Products like these will help address the issue of attracting young<br>
> blood to the HAM hobby. A further improvement would be reducing the<br>
> learning curve by explaining what KISS, APRS, and TNC is. Newcomers<br>
> have no idea why they should be interested in whatever those acronyms<br>
> mean. I only got a taste of what APRS was last night watching a<br>
> youtube video of some guy running a telnet sessions over his radio at<br>
> 1200 baud: <a href="https://www.youtube.com/watch?v=f-Be8e2tclU" rel="noreferrer" target="_blank">https://www.youtube.com/watch?v=f-Be8e2tclU</a><br>
<br>
</span>A TNC is a Terminal Node Controller, or basically an intelligent message<br>
processor (IMP), an interface box that allows a user on a dumb terminal<br>
to communicate with other users through a transmission medium with IMPs<br>
at both ends. The TNC contains a modem, packet buffer, and interface<br>
control logic to control a radio transmitter, modulate the transmitter,<br>
and decode the audio from the receiver.<br>
<br>
<a href="https://en.wikipedia.org/wiki/Interface_Message_Processor" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/Interface_Message_Processor</a><br>
<a href="https://en.wikipedia.org/wiki/Terminal_node_controller" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/Terminal_node_controller</a><br>
<a href="https://en.wikipedia.org/wiki/Packet_radio" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/Packet_radio</a><br>
<br>
TAPR gave birth to the TNC:<br>
<a href="https://www.tapr.org/packetradio.html" rel="noreferrer" target="_blank">https://www.tapr.org/packetradio.html</a><br>
<a href="https://www.tapr.org/kits_119.html" rel="noreferrer" target="_blank">https://www.tapr.org/kits_119.html</a><br>
<br>
KISS is a TNC specific serial protocol:<br>
<a href="https://en.wikipedia.org/wiki/KISS_%28TNC%29" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/KISS_%28TNC%29</a><br>
<br>
KISS is designed to place the received packets on the serial bus as<br>
quickly as possible with as little extraneous information as possible,<br>
and to do the same on transmit.<br>
<br>
eXtended KISS (XKISS) is a multi-dropped (like RS-485) version of KISS<br>
that allows for attaching multiple devices (TNCs or computers) to a<br>
shared serial bus. G8BPQ's node stack supports this, and the Kantronics<br>
KPC-9612 supports this as well, providing two "distinct" virtual TNCs<br>
when used in XKISS or KISS mode.<br>
<br>
There are hardware TNCs, originally based on RS232 serial<br>
communications. TNCs have been made that used the Zilog Z80 (TAPR TNC2)<br>
and Motorola 68HC11 (Kantronics KPC-series). There are now software<br>
TNCs, for both Windows and Linux which use sound cards.<br>
<br>
The "over-the-air" protocol is called AX.25, which is an extension of<br>
the X.25 network stack:<br>
<a href="http://tldp.org/HOWTO/AX25-HOWTO/x61.html" rel="noreferrer" target="_blank">http://tldp.org/HOWTO/AX25-HOWTO/x61.html</a><br>
<a href="https://en.wikipedia.org/wiki/AX.25" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/AX.25</a><br>
<br>
There are also node stacks, both hardware (TheNet, ROSE) and<br>
software such as G8BPQ, JNOS, TNOS:<br>
<a href="http://www.cantab.net/users/john.wiseman/Documents/" rel="noreferrer" target="_blank">http://www.cantab.net/users/john.wiseman/Documents/</a><br>
<a href="http://kf8kk.com/packet/jnos-linux/thenet-ops-1.htm" rel="noreferrer" target="_blank">http://kf8kk.com/packet/jnos-linux/thenet-ops-1.htm</a><br>
<a href="https://www.tapr.org/pdf/DCC1993-ImprovedTNCinterconnections-N2IRZ.pdf" rel="noreferrer" target="_blank">https://www.tapr.org/pdf/DCC1993-ImprovedTNCinterconnections-N2IRZ.pdf</a><br>
<br>
<a href="http://kf8kk.com/packet/jnos-linux/jnos-ops-1.htm" rel="noreferrer" target="_blank">http://kf8kk.com/packet/jnos-linux/jnos-ops-1.htm</a><br>
<a href="http://www.langelaar.net/jnos2/" rel="noreferrer" target="_blank">http://www.langelaar.net/jnos2/</a><br>
<a href="http://www.linux-ax25.org/wiki/TNOS" rel="noreferrer" target="_blank">http://www.linux-ax25.org/wiki/TNOS</a><br>
<br>
AGWPE works as both a sound card software TNC and a node stack:<br>
<a href="http://www.sv2agw.com/ham/agwpe.htm" rel="noreferrer" target="_blank">http://www.sv2agw.com/ham/agwpe.htm</a><br>
<br>
There is/was TCP/IP stuff, but it's not used with APRS:<br>
<a href="https://en.wikipedia.org/wiki/AMPRNet" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/AMPRNet</a><br>
<a href="http://www.ampr.org/" rel="noreferrer" target="_blank">http://www.ampr.org/</a><br>
<a href="http://wiki.ampr.org/wiki/Main_Page" rel="noreferrer" target="_blank">http://wiki.ampr.org/wiki/Main_Page</a><br>
<br>
Tim, N8DEU, may be a better source for what APRS and packet are than<br>
myself. I tend to look at things as what you can do with them, as<br>
opposed to what they are said to be. APRS is many things, part network,<br>
part application, part message-passing.<br>
<br>
One analogy would be a single-frequency network composed of simplex,<br>
half-duplex repeaters which repeat something like UDP frames of<br>
information and limited broadcast domain control logic combined with a<br>
little bit of intelligent message routing.<br>
<br>
But 1200 bps half-duplex is slower than it appears to be, however there<br>
is compression involved in some APRS packets.<br>
<br>
Over-arching project itself:<br>
<a href="https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System</a><br>
<a href="http://www.aprs.org/" rel="noreferrer" target="_blank">http://www.aprs.org/</a><br>
<br>
"Backbone" / "Internet Infrastructure": <a href="http://www.aprs-is.net/" rel="noreferrer" target="_blank">http://www.aprs-is.net/</a><br>
IGate: <a href="http://www.aprs.net/vm/DCC97/internet/" rel="noreferrer" target="_blank">http://www.aprs.net/vm/DCC97/internet/</a><br>
<a href="http://www.findu.com/" rel="noreferrer" target="_blank">http://www.findu.com/</a><br>
<br>
Applications:<br>
Google Maps + APRS-IS: <a href="http://aprs.fi/" rel="noreferrer" target="_blank">http://aprs.fi/</a><br>
<a href="http://www.findu.com/" rel="noreferrer" target="_blank">http://www.findu.com/</a><br>
<br>
Text messaging from internet to APRS:<br>
<a href="http://www.aprs.org/aprs-messaging.html" rel="noreferrer" target="_blank">http://www.aprs.org/aprs-messaging.html</a><br>
<a href="http://www.findu.com/cgi-bin/entermsg.cgi" rel="noreferrer" target="_blank">http://www.findu.com/cgi-bin/entermsg.cgi</a><br>
<a href="http://www.aprs-is.net/email.aspx" rel="noreferrer" target="_blank">http://www.aprs-is.net/email.aspx</a><br>
<a href="http://aprsisce.wikidot.com/doc:aprs-messaging-explained" rel="noreferrer" target="_blank">http://aprsisce.wikidot.com/doc:aprs-messaging-explained</a><br>
<br>
Single-frequency networking:<br>
<a href="https://en.wikipedia.org/wiki/Single-frequency_network" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/Single-frequency_network</a><br>
<a href="http://www.aprs.org/fix14439.html" rel="noreferrer" target="_blank">http://www.aprs.org/fix14439.html</a><br>
<a href="http://www.aprs.org/fixingLA.html" rel="noreferrer" target="_blank">http://www.aprs.org/fixingLA.html</a><br>
<br>
It's also important to point out that there's more than one way to<br>
modulate a transmitter. 1200 bps APRS relies on the ad-hoc standard of<br>
Bell 202 modem + commodity two-way radio = signaling inside of the voice<br>
bandwidth (300 - 3,000 Hz) without equalization or correction.<br>
<br>
We have other speeds such as:<br>
<br>
2400 bps is the fastest speed inside the voice bandwidth (for now). This<br>
required special modules to go into the TNC, changing jumpers, etc.<br>
9600 bps GMSK/GFSK using modified radios or special, standardized ports on the radio now.<br>
19,200 bps required special radios and/or special TNCs, or serial cards,<br>
or mods to TNC and/or radios (replacing IF filters, tapping into the<br>
modulator directly).<br>
56,000 bps required a special ISA card (PI-2) with a Zilog Z8530 serial<br>
processor which natively built X.25 frames and performed synchronous<br>
serial communications, as well as the GRAPES modem and modified<br>
transverters: <a href="http://www.wa4dsy.net/rfmodem.html" rel="noreferrer" target="_blank">http://www.wa4dsy.net/rfmodem.html</a><br>
<br>
And that's just the tip of the iceberg. There are other modes yet to be<br>
discovered or implemented to maximum the bandwidth of a 0-4KHz audio<br>
path or 300 - 4,000 Hz audio path.<br>
<br>
V.90 or V.92 maximized the bandwidth of what could be obtained in a<br>
voice-grade audio path at about 33.6KHz, but those modems are encumbered<br>
by patents. Carrier frequency is 3429 Hz, however. But those modems also<br>
don't work in half-duplex -- they are full-duplex only.<br>
<div class="HOEnZb"><div class="h5"><br>
--<br>
Kris Kirby, KE4AHR<br>
Disinformation Architect, Systems Mangler, & Network Mismanager<br>
<br>
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</div></div></blockquote></div><br></div>