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

Tue Apr 20 23:10:06 EDT 2004

I have a KAM '98, which I use with MMTTY for RTTY Dxing. WinWarbler lets
me run both simultaneously, displaying the received characters from each
in adjacent (over/under) panes. While MMTTY generally produces better
copy, the KAM often provides fills for text mis-decoded by RTTY.
Sometimes those misses occur while I'm rapidly switching MMTTY profiles
in hopes of getting better copy. I've added EU1SA's profile to my
repetoire, and look forward to assessing it's performance.

I wouldn't go buy a KAM if I didn't already have one, but if you have a
RTTY modem laying around there's an advantage to "diversity decoding",
even if MMTTY is usually the better decoder.

    73,

        Dave, AA6YQ

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com]
On Behalf Of Jim McDonald
Sent: Tuesday, April 20, 2004 22:51
To: RTTY Reflector
Subject: Re: [RTTY] A repository of (poor) RTTY recordings?

I used a KAM Plus for several years but sold it after buying a P38 (at
Dayton in 1998) and later using MMTTY too.  I had modified the KAM to
allegedly improve performance with weak signals.  I apparently shipped
the info on the mod with the unit when I sold it.  I would have thought
I got the mod from Kantronics but I don't remember where.  If anyone is
still fooling with them, you might root around for the mod.

Incidentally, I had lots of interest in mine after advertising it on
qth.com and qrz.com.  I think the interest was from MARS operators using
Pactor or some other mode but not Baudot.  So just because we have found
a better solution don't assume everyone is of the same opinion.

Jim N7US

----- Original Message ----- 
From: "Terry" <terry at ab5k.net>
To: "RTTY Reflector" <rtty at contesting.com>
Sent: Tuesday, April 20, 2004 3:28 PM
Subject: Re: [RTTY] A repository of (poor) RTTY recordings?

>Anyone willing to host such sound files on their web site?
I can do a FTP host or put them on a web page on the site here.

I recently compared three KAM's to MMTTY.  The test was simple find a
RTTY signal and add attenuation to the receiver until the signal was in
the noise
floor.  The result were that MMTTY won in all cases.   The three KAM's
are
headed to the next hamfest.

In the recent EA-WW RTTY test, I set up a test on the laptop and ran 5
instances of MMTTY running different settings.   The intent was to
compare
copy of the EU and JA signals under weak conditions.   No obvious
conclusions were made and the band conditions were way down so this test
needs more analysis.

73 Terry - AB5K

Web: www.ab5k.net
AR-Cluster:  dxc.ab5k.net and dxc-us.ab5k.net

----- Original Message ----- 
From: "Kok Chen" <chen at mac.com>
To: "RTTY Reflector" <rtty at contesting.com>
Sent: Tuesday, April 20, 2004 3:53 PM
Subject: [RTTY] A repository of (poor) RTTY recordings?

> 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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>

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