[RTTY] A repository of (poor) RTTY recordings?

[Kok Chen <chen@mac.com>]

It is perhaps useful for the RTTY community to have available a 
"standard" collection of digitized sound files of various RTTY signals. 
 Not the clean loud stuff that we already have on the web as examples 
of FSK, but some watery fluttery hard to copy, etc. stuff.

All of us could then use the same digitized sound files to play back 
into whatever system we are testing so there would be some consistency.

The "print" between modems and between different settings of the same 
modem can then be compared.  Even a 30-second recording would already 
provide near 200 characters of decoded Baudot and provide statistically 
significant comparisons between modems.

I have some files which I use for my own tests (including equatorial 
flutter FSK and broadband PSK31 recordings) in AIFF format (but which 
could easily be converted to WAV format).  I am sure there are others 
on this reflector who have made similar recordings.  We could also 
easily alter the files to make the samples appear to come from a poorly 
gain adjusted setup by shifting the A/D samples a few bits down.

I don't run MMTTY, but people who do can try each recording with 
different parameter settings.  I presume MMTTY can take audio samples 
from a file in addition of from a sound card?  If not, though not 
ideal, you can play the sound back from a second computer into the 
computer with MMTTY.  A similar thing could be doe when testing 
hardware modems. (Or first burning the sound files into some external 
format a CD or MP3 player can play back.)

Anyone willing to host such sound files on their web site?   Equally, 
are people willing to contribute some sound files?

If there are only a couple of us interested in this technical aspect of 
RTTY, I am willing be responsible to do a CD-ROM distribution instead 
of a web page, as long as I can get you guys to send some good 
candidate sound files to me.

73
Chen, W7AY



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