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Robert Bruninga wrote:
<blockquote cite="mid:623B06D5930442E68584926DC88A7CD1@ewlab.usna.edu" type="cite">
<pre wrap="">EchoLink/IRLP for the APRS mobile:
But I was surprised when I was rejected by a digi operator that
would not support EchoLink at all, and only IRLP. I thought
this battle was over long ago, and that the two are getting
along quite well. I know there is a bias against all the
non-radio Shack-potato's on EchoLink (same problem with
shack-potato's on APRS), but, then this initiative to get these
objects on APRS has nothing to do with the shack-potatos, only
on-air ooperation. We are only interested in OPEN Echolink
Repeaters or links. Can someone enlightmen me if this
anti-echolink bias is still pervasive?
</pre>
</blockquote>
<br>
There are significant differences between the two systems:<br>
<br>
o IRLP is Linux-based and requires a specialized purpose-built
hardware interface between the computer and the radio. (Which
physically makes the "shack potato" mic-and-speaker-in-front-of
the-computer mode impossible.)<br>
<br>
o Echolink is is Windows-based and has no specific hardware
requirements. Echolink's termination on the computer can be anything -
a sound card interface to a user's radio, a mic & speaker, the TX
and RX audio lines of a repeater, etc. Echolink incorporates
SOFTWARE DTMF decoding and SOFTWARE VOX-like audio detection for RX
activity which can eliminate the need for bringing a receiver COR or
squelch line out of the radio. (Though it will sense COR through a
serial port's DCD hand shaking line and works FAR better if you do
so.) <br>
<br>
<br>
The result is that IRLP setups tend to be by the serious hardcore
techie faction of amateur radio. By contrast, because of it's
minimal hardware requirements and seemingly simple setup, Echolink
nodes are often just "thrown up" by casual appliance operators. There
tends to be some overtones of the Linux-vs-Windows religious war among
the two factions. <br>
<br>
Assuming they ARE actually connected to a radio instead of a computer
mic & speakers, many Echolink installations are crude lashups with
radio speaker and mic audio connections wired directly to a computer
sound card with no attempt to properly match audio levels,
de-emphasis/pre-emphasis equalization or ground-loop isolation, and
with no positive COR-based TX/RX sensing. <br>
<br>
Many so-called Echolink "repeater" connections are not connected to the
repeater at all, but are actually just users' radios listening to a
repeater channel from miles away. In this mode, the Echolink interface
has no positive way to sense the repeater receiver's
COR/squelch/"activity" indicator. As a result, double squelch crashes
get fed into the Internet connection -- first the repeater squelch,
then the user's radio squelch. Worse, long repeater tails can confuse
the Echolink VOX -based "COR" by sensing "silence" during the tail,
causing the Internet user to try to transmit before the repeater
carrier has dropped and reset it's timer. This is aggravated by the 2
second or more round-trip propagation delay over the Internet. <br>
<br>
By the time a mobile user's TX audio reaches the Internet in such
lashups, (and has been pre-de-re-de-emphasized FOUR times by his own
radio's TX audio system, the repeater receiver audio system, the
repeater transmit audio system and then the remote Echolink receiver's
audio system, each with less-than-optimum response curves), the
Internet user frequently experiences horribly distorted muffled muddy
audio at wildly high or very low levels. <br>
<br>
This is not to say you can't have high-quality audio on Echolink. You
can. I actually built a separate op-amp-based precision de-emphasis
network directly off the receiver discriminator for my Echolink node,
and precisely set the TX level so that 95% level from the Internet
corresponded to exactly 4.5 KHz deviation over the air. <br>
<br>
In the "shack potato" mode, at least half the users try to close-talk
junk computer electret multi-media mics resulting in muddy muffled
bass-heavy nearly un-intelligible audio. [Echolink does provide a
software-based TX-audio bass-cut function that reduces this problem but
the appliance operators never read enough to discover this fact.] <br>
<br>
[A little-known fact, due to the fact that most users don't RTFM, is
that you can connect a normal mobile radio hand mic's audio to the
sound card MIC IN and the mic's PTT line to one of the handshaking
lines of a serial port. This then allows you to use a
communications-grade mic with normal PTT EXACTLY the way you would on a
radio!]<br>
<br>
A large percentage of these clueless users:<br>
<br>
a) Don't know how to find and use the Windows record mixer to set
their outgoing audio level, and <br>
<br>
b) Don't comprehend the huge difference between talking to another
computer-only shack potato (with an essentially noiseless background
that renders proper level setting non-critical) and talking to a radio
user (where getting the link radio fully deviated with clean audio is
essential to the mobile listener.<br>
<br>
At least 4 or 5 times a day, I get random connects to my Echolink node
from clueless shack pototatos that can't figure out how to set their TX
(Windows record) audio level (often no audio at all) and can't figure
out how to switch from RX to TX. I get 15-30 seconds of dead audio
before either I or they disconnect....<br>
<br>
BOTTOM LINE: The Echolink software is an incredibly sophisticated
& capable program, but the deceptively-simple typical Windows
"run-Setup-and-use" interface encourages far, far too many half-assed
setups by uninformed end-users that WON'T RTFM first!<br>
<br>
<hr size="2" width="100%"><br>
<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>
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>
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