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Jaye Inabnit ke6sls wrote:
<blockquote cite="mid:201007200914.28123.ke6sls@arrl.net" type="cite">
<pre wrap="">I am most interested
in finding low power I-gate hardware that I can install either here at my QTH
or at our low level repeater site.
</pre>
</blockquote>
<br>
1) Don't confuse digipeaters (RF-->RF relay function) with
igates (RF<-->Internet connections). Digipeaters are located
at places with good radio coverage; i.e. ideally on hilltops or tall
buildings. Igate setups are located where you have always-on Internet
access. <br>
<br>
2) Unfortunately, you will NOT typically have Internet access at
remote hill top repeater sites. <br>
<br>
3) Igates are normally located at home or office locations where you
DO have always-on Internet access. As long as you can hear the
digipeater(s) decently at these home or office locations with Internet
access , the elevation/antenna height of the station doing igate duty
is not critical. <br>
<br>
4) An igate setup will consist of a radio, TNC, and a computer with
an Internet connection running a suitable program. It could be a
dedicated igate-only program, --or-- a general-purpose APRS client
such as UIview, APRSplus or the Linux-based Xastir. These three
programs can all do triple duty as an end-user client producing map
displays and messaging, act as an igate, and act as a digipeater at
the same time. Unless you live in the dream high-rent district on the
hilltop overlooking town, the digi will probably be configured as a
low-level WIDE-1-1 "fill-in" digi (if you enable it at all). <br>
<br>
You do not need bleeding-edge multi-core gamers machines with HD
displays to run APRS software. Even old Pentium II or III "clunkers"
will do the job decently running Win98, Win2K or a Linux distro. This
is an ideal use for elderly computers.
For minimal hardware and lowest power consumption, consider older
laptops. For unattended igate operation, you can live with small
low-resolution screens that would be considered unusable for most of
today's software. A virtue of older machines is that, unlike any of
today's current models, they usually have REAL SERIAL PORTS without
the
hassle of USB<-->serial adapter "dongles". [Serial ports are
essential for connecting TNCs, or the Kenwood radios with built-in
TNCs, to computers.]<br>
<br>
<br>
5) Note that more digipeaters can contribute to on-air congestion
and actually REDUCE the channel capacity, if there is already
adequate digi coverage in the area. This is because, unlike voice
repeaters, APRS digipeating is not a simultaneous process. A station
makes a transmission, the digipeater hears it and stores it in memory
briefly, and then retransmits it AFTER the original station's
transmission. <br>
<br>
Even a single digipeat DOUBLES the air time each user occupies, cutting
the channel throughput (number of packets per minute) in half. An
added digipeater can potentially cause each transmission to occupy a
THIRD time slot, cutting the channel capacity to ONE-THIRD of the
no-digipeaters scenario (assuming that the original transmission and
both digipeats are heard over the same area; i.e. not just at a distant
location.). <br>
<br>
6) Igates normally DO NOT reduce over-the-air channel capacity. The
bandwidth of the Internet is essentially unlimited, compared to
over-the-air operation at 1200 baud. In general, the more igates the
better. The sooner (in terms of hops) you get packets off the air and
into the Internet, the less on-air congestion and chances for RF
collisions. <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>
<hr size="2" width="100%"><br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: WA8LMF or 14400 [Think bottom of the 2M band]<br>
Skype: WA8LMF<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
NEW! *** 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>
Universal HF/VHF/UHF Antenna Mounting System<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/mobile/UniversalAntMountSystem.htm">http://wa8lmf.net/mobile/UniversalAntMountSystem.htm</a><br>
<br>
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