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On 3/20/2012 9:23 AM, Mike Goldweber wrote:
<blockquote
cite="mid:20120320062340.6285e77fd289b2245967c6ea4157de00.f7630daba1.wbe@email09.secureserver.net"
type="cite"><span style="font-family:Verdana; color:#000000;
font-size:10pt;">
<div>Hi Everyone,</div>
<div><br>
</div>
<div><br>
</div>
<div>So I'm a little confused. I can imagine a pure internet
set of links (and displayed nodes), and I can imagine a set of
pure radio linked nodes. I am a little confused about what
seems to be a partial mix of internet or radio nodes. Could
someone please explain the mechanics of this to me?</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Mike Goldweber</div>
<div>KB3IXO</div>
</span><br>
</blockquote>
<br>
<br>
1) APRS began as a purely RADIO-based system based on AX.25
packet radio (data transmission over over radio) some decades ago.<br>
<br>
2) The APRS-IS (APRS Internet System) was added to the
radio-based network some years later. <br>
<br>
3) Normally, traffic heard on RF is passed to the Internet system
of dedicated APRS servers, by radio base stations with Internet
connections (Internet Gateway stations a.k.a. "igates"). Once
passed to the Internet, traffic can be monitored on connected
devices, or by viewing public websites such as Findu.com or APRS.fi
. Virtually EVERYTHING heard on RF by an igate station will be
passed into the APRS-IS. <br>
<br>
4) Because the 1200-baud radio channel has such severely limited
capacity compared to the Internet, traffic passes the other way
(Internet-to-RF a.k.a. "reverse gating") only under certain very
limited conditions. Normally, only messages directed to a
specific station (but not the usual broadcast location beacons) will
pass Internet-to-RF. <br>
<br>
In order for such a message to pass from Internet to RF, the RF
station being addressed must have been heard recently (typically
within the last hour) and nearby (either heard directly by an igate
station, or within only one over-the-air digipeater hop). <br>
<br>
5) This may seem obvious, but many newcomers unwittingly assume
the APRS network has the same kind of ubiquitous coverage as
cellular networks. It DOESN'T! The APRS network has nowhere
near the number of base station igate sites as cellular network have
cell sites. The APRS RF network has large coverage holes in many
parts of the country. If the RF station being addressed has NOT
been heard recently, or is not within range of an igate station,
then messaging attempts Internet-to-RF will fail. <br>
<br>
6) The APRS Internet System can function, in a manner similar to
EchoLink or IRLP, as a kind of "wormhole" connecting two radio users
too far apart to communicate directly with each other by
radio-only. In this case, the limitations on what will pass
Internet-to-Rf will apply to BOTH parties involved. I.e. BOTH
parties need to be within the local coverage area of igate stations.
<br>
<br>
<br>
<hr size="2" width="100%"><br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
Skype: WA8LMF<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
***** NEW Precision Mapping 9 For UIview Released! *****<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/PMap9_Notes.htm">http://wa8lmf.net/aprs/PMap9_Notes.htm</a><br>
<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>
30-meter 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>
<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>
<br>
<br>
<br>
<br>
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