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On 11/14/2011 9:24 AM, <a class="moz-txt-link-abbreviated" href="mailto:kc8sfq@mei.net">kc8sfq@mei.net</a> wrote:
<blockquote
cite="mid:d6287b5e036d5290cac3f173e6787885.squirrel@smail.mei.net"
type="cite"><br>
Hi All:<br>
I have an old MFJ1274 TNC. I'm thinking of
putting it, along with a radio and a gel cell battery, in a
waterproof box
for use as a temp DIGI for SAR and similar such field use.<br>
<br>
What
I know about the MFJ:<br>
1: It won't work with APRSISCE/32 (my fav)
since it won't stay in KISS mode.<br>
2: It'll require a new EPROM for
extended KISS operation. That's about $40-50 by the time it's all
up and
running. There are better and easier ways to do that for the same
money.<br>
</blockquote>
<br>
Replace the eprom with the last-ever TAPR Release 1.1.9 firmware
which has a perfectly serviceable KISS implementation in it. <br>
<br>
<blockquote
cite="mid:d6287b5e036d5290cac3f173e6787885.squirrel@smail.mei.net"
type="cite"><br>
My questions:<br>
1: Will the MFJ1274 support the new
n-N paradigm? or will it need to be addressed by it's specific
callsign-SSID? (I know it's been upgraded to at least 1.2.9
firmware)<br>
</blockquote>
<br>
Not as-is, with the exception that if all you want it to do is be a
home-style first-hop fill-in digi, then set it's callsign "alias" to
"WIDE1-1" . (The first-hop WIDE1-1 digipeating doesn't depend on the
TNC having the APRS-centric callsign-changing/substituting
capability described below.)<br>
<br>
<blockquote
cite="mid:d6287b5e036d5290cac3f173e6787885.squirrel@smail.mei.net"
type="cite"><br>
2: will the MFJ even function as an APRS DIGI? (my understanding
is that there's nothing special about an APRS packet as far as a
DIGI is
concerned)<br>
</blockquote>
<br>
But there ARE major differences between classic connected packets
and APRS packets ! <br>
<br>
From the standpoint of the AX.25 protocol used by both "classic"
packet and APRS, the path settings are the callsign(s) of the
station(s) being asked to relay the packet. In classic packet,
these would be the actual calls of the stations involved; i.e. you
had to know in advance the calls of the stations involved to get a
packet relayed. In APRS, all stations respond to the same generic
"callsigns" of WIDE1-1, and/or WIDE2-n. <br>
<br>
Current "New Paradigm" APRS depends on digipeaters being able to
actually CHANGE these "callsigns" as packets pass through them --
something classic packet NEVER did. APRS digis modify these
"calls" as they pass the packet on, to track and control the number
of relay hops. For example, WIDE2-2 becomes WIDE2-1 which becomes
WIDE2-0 as a packet passes through 3 successive digis. This
handling of callsigns is unique to APRS. <br>
<br>
Many of the new-breed low-cost KISS-only APRS-only TNCs such as
TinyTrack 4, Tracker2, TNC-X, AGW uTNC, etc CAN do APRS-style
digipeating stand-alone. The ONLY "classic" TNCs able to do this
off-the-shelf stand-alone (i.e. unassisted by computer programs),
were the Kantronics KPC3 family TNCs. PK-232s, TNC2s, etc require
a computer program running through a KISS interface to do modern
APRS digipeating. <br>
<br>
You can endow almost any TNC-2 clone, such as your MFJ with this
ability by replacing it's OEM firmare with the freeware UI-Digi
firmware that converts the TNC2 to a dedicated APRS digipeater.
However it becomes STRICTLY a stand-alone digipeater, and can no
longer be used for local transmit/receive by a an attached PC. <br>
<br>
<br>
See the full history and underlying logic of APRS digipeating here
on my website:<br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/DigiPaths">http://wa8lmf.net/DigiPaths</a> <br>
<br>
<hr size="2" width="100%"><br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
=== Now relocated from Pasadena, CA back to 8-land (East Lansing,
MI) ===<br>
Skype: WA8LMF<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
===== Vista & Win7 Install Issues for UI-View and Precision
Mapping =====<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7">http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7</a><br>
<br>
*** HF APRS over PSK63 ***<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRS_PSK63/index.htm">http://wa8lmf.net/APRS_PSK63/index.htm</a><br>
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