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<p><font face="Arial">[2 Feb 2025]<br>
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<p><font face="Arial">i originally released version 1 of the
"WA8LMF TNC Test CD" in 2006, with with a slight update,
version 1.1, in 2009.</font></p>
<p><font face="Arial">This was an image file that created an audio
CD. The disk contains a variety of recordings of packet APRS
transmissions to verify/compare the performance of packet TNCs
(both hardware and software). Over the past 16 years it has
become sort of a de-facto standard for testing/comparing various
packet radio receiving systems. <br>
</font></p>
<p><font face="Arial">In 2009, computer CD systems were plagued with
cheap unstable software-based audio decoding (the infamous
"AC97" codec) that used system interrupts for timing. The audio
sample rate would actually vary, depending on CPU loading and
the number of tasks currently running on the computer. </font></p>
<p><font face="Arial">On the other hand, AUDIO CD players (even
cheap boomboxes and DiscMan portables) used stable
crystal-controlled time-bases. </font><font face="Arial">In
2009, I chose to produce the disk as an audio CD (not a CD-ROM
with .WAV files) to yield more accurate and repeatable tests of
TNC performance. </font></p>
<p><font face="Arial">The ver 1.1. CD was produced in the "CD-Extra"
format that combines CD audio tracks playable on a music CD
player -- with a data CD-ROM area accessible with a computer
CD/DVD drive. (This hybrid format is sometimes used on modern
music CDs to include song lyrics, artist bios, etc on the disk
along with the music.) <br>
Some users have had problems with recording the BIN/CUE
format of the TNC Test image file to physical CDs. (This
now-somewhat-obscure disk-image format was required because the
more-common .ISO disk image format can't handle the mixed-mode
half-music-CD/half-CD-ROM format of the disk.)<br>
</font></p>
<p><font face="Arial">Today, the "horsepower" of the average
computer has increased orders of magnitude since 2009. More
importantly, for the last decade or so, most computers have been
equipped with the "RealTek HD" audio chips that use an accurate
crystal-controlled time-base. As a result, computer-playback of
audio files is now very accurate with stable sample rates. </font></p>
<p><font face="Arial">I have now re-released the Test CD as a
standard CD-ROM in the common .ISO image format. This disk
contains the identical test audio tracks, but now stored as
lossless FLAC files. The .ISO image file can be used to burn a
physical CD. Or the .ISO file can be used as-is, "mounted" as
a virtual CD-ROM drive using an used drive letter on your
system. Or the FLAC-format audio files could be copied to a
flash drive.</font></p>
<p><font face="Arial">I have extensively revised the page on my web
site for the Test CD . It now includes download links for both
the original ver 1.1 audio CD image, and the new ver 2.0 .ISO
CD-ROM image. </font></p>
<p><font face="Arial"> <a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net/TNCtest/"><http://wa8lmf.net/TNCtest/ ></a></font></p>
<p><font face="Arial"><br>
</font></p>
<hr width="100%" size="2"><font face="Arial">Stephen H. Smith
wa8lmf (at) aol.com <br>
Skype: WA8LMF<br>
EchoLink: Node # 14400 [Think bottom of the 2-meter band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
New 30 Meter APRS-over VARA Frequency <br>
As of 1 Jan 2025. Details Here:<br>
<a class="moz-txt-link-rfc2396E" href="http://WA8LMF.net/VARA/NewFrequency.htm"><http://WA8LMF.net/VARA/NewFrequency.htm></a><br>
<br>
- APRS over VARA --<br>
<a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net/VARA/APRSoverVARA"><http://wa8lmf.net/VARA/APRSoverVARA></a><br>
<br>
"Studio B" Ham Shack on Wheels<br>
<a class="moz-txt-link-rfc2396E" href="http://WA8LMF.net/Aliner"><http://WA8LMF.net/Aliner></a><br>
<br>
-<br>
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