[aprssig] WA8LMF "TNC Test CD" RE-Released!

[Stephen H Smith]

[2 Feb 2025]

i originally released  version 1 of the "WA8LMF TNC Test CD"   in 2006, with 
with a slight update, version 1.1, in 2009.

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.

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.

On the other hand, AUDIO CD players (even cheap boomboxes and DiscMan 
portables) used stable crystal-controlled time-bases. 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.

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.)
     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.)

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.

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.

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.

<http://wa8lmf.net/TNCtest/ >


-------------------------------------------------------------------------------
Stephen H. Smith wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page: http://wa8lmf.net

New  30 Meter   APRS-over VARA  Frequency
As of 1 Jan 2025.   Details Here:
<http://WA8LMF.net/VARA/NewFrequency.htm>

- APRS over VARA  --
<http://wa8lmf.net/VARA/APRSoverVARA>

"Studio B" Ham Shack on Wheels
<http://WA8LMF.net/Aliner>

-



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/aprssig_lists.tapr.org/attachments/20250202/a9ba2d01/attachment.htm>