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William McKeehan wrote:
<blockquote cite="mid:3046.192.168.1.1.1187108001.squirrel@mckeehan.homeip.net" type="cite">
<pre wrap="">Has anyone looked at D-Star as a potential replacement for APRS?
It seems to have a lot of the basic functionality.
</pre>
</blockquote>
<font face="Arial">There are a LOT of technical, organizational and
political obstacles to this ever happening.<br>
<br>
</font><font face="Arial">Partly as a result of the APRS founders
shoe-horning
and somewhat kludging APRS into the protocols, hardware and
infrastructure of the preceding connected-packet era (do I dare use
that over-used buzzword "leverage"?), </font><font face="Arial">APRS
has succeeded because it has allowed us to do a lot of "neat stuff"
with really cheap existing hardware. This will *NOT* be the case
with D-Star. A migration to D-Star will be a wrenching total
transition to *ALL NEW* base stations, mobiles, hand-helds and repeater
infrastructure. </font><font face="Arial"><br>
<br>
<br>
D-Star is not a short-burst packetized transmission format. It's
primarily a digitized voice format that can carry a limited amount of
other data embedded in the main voice data stream. As a result, the
simple single-frequency store-and-forward "digipeaters" we use on APRS
won't work with it. You would be faced with coordinating a
traditional full-blown two-frequency "repeater pair", along with using
a separate receiver, transmitter and duplexer, just like present voice
repeaters. Further , getting more than one repeater hop isn't a
matter of the second repeater hearing the first one, and then
retransmitting what it hears a moment later. It involves a complex
land-mobile-style backbone of links on another band, usually 1200 MHz
to connect repeaters together in real time.<br>
<br>
Further, no manufacturer seems to have adopted it, except Icom. <br>
<br>
While the only mfr to officially support APRS is Kenwood, at least you
*CAN* add APRS hardware (TNCs, TinyTracks, Open Tracks, etc.) to other
radios. This is not going to be the case with D-Star which is an
entirely digital modulation technique totally different from the analog
FM we use with APRS packet, that is built-into purpose-built radios.
It is very unlikely you would be able to add D-Star to any existing
radio, especially hand-helds. <br>
<br>
Achieving anything remotely like the coverage of the current
analog-FM-packet-based APRS network (where just about any FM radio made
in the last 30 years or so can be pressed into duty as a digipeater by
adding a $50 TNC). Duplicating this coverage with D-Star would require
literally tens of millions of dollars of brand-new infrastructure. <br>
<br>
Further, the present network reflects the sum total of a lot of small
steps made independently by clubs and individuals. A nationwide D-Star
"APRS- replacement" infrastructure would require a degree of
coordination (and financial commitment) by clubs and individuals
unprecedented in amateur radio. <br>
<br>
My guess is that we will get "islands" of D-Star activity in major
metropolitan areas (where the population density of hams is great
enough to support the major infrastructure investments required) ,
surrounded by hundreds (or thousands) of miles of non-coverage. I.E.
the individual ham or small club in a small mid-western town or rural
Kentucky that threw up an old hand-me-down 2-meter rig and a TNC to
fill in the APRS network at almost no cost, is NOT going to lay out
the several thousand dollars minimum to put up a D-Star repeater, let
alone the backbone to link it to other D-Star systems. <br>
<br>
Before they make this major investment, users are far more likely to
use Internet access from their cellphones to send/display GPS position
reports and send/receive short text messages. (Envision an APRS-like
application overlaid on Google Maps running on an iPhone-like device.]<br>
<br>
</font><font face="Arial"><br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: 14400 [Think bottom of the 2M band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.com">http://wa8lmf.com</a> --OR-- <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
NEW! World Digipeater Map<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRSmaps">http://wa8lmf.net/APRSmaps</a><br>
<br>
JavAPRS Filter Port 14580 Guide <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/JAVaprsFilters.htm">http://wa8lmf.net/aprs/JAVaprsFilters.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>
Updated "Rev H" APRS <a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs">http://wa8lmf.net/aprs</a><br>
Symbols Set for UI-View, <br>
UIpoint and APRSplus:<br>
<br>
<br>
<br>
<br>
<br>
</font>
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