[GreenKeys] TU for Computer

[W7HPW Radio]

Jim,

"I think I was told that MMTTY has a Baudot output, but that may not be
true and I haven't looked."

I have used MMTTY for years, as far as I know it does not

Mark
W7HPW

-----Original Message-----
From: Jim Haynes [mailto:jhhaynes at earthlink.net] 
Sent: Thursday, January 10, 2019 7:36 PM
To: W7HPW Radio
Cc: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] TU for Computer

Yes and no.  Of course you are aware of all the computer software that
turns the computer into a complete RTTY terminal, but I think what you
are asking is for software that replaces the demodulator with digital
signal processing so you can drive a TTY machine with the Baudot output.

The earliest DSP software was K6STI's RITTY program.  I talked him into
providing a cleaned-up Baudot output when it was receiving, but didn't
ask him to provide for a TTY keyboard input.  The story of that software
is that it ran under DOS, required a certain kind of SoundBlaster
sound card, and was rather expensive.  He pulled it off the market
because it was being pirated, and also never ported it to anything beyond
DOS and a more generic sound system.  I think he said it was not possible
to do that and maintain the performance it gave.

I shouldn't say that was the earliest - there was probably some using a
dedicated DSP engine, but K6STIs was the first to use a PC that I know
of.  And you didn't find many Pentium computers running DOS even back
then.

I think I was told that MMTTY has a Baudot output, but that may not be
true and I haven't looked.

I've begged Dave W1HKJ to add a Baudot output to fldigi but apparently
that is either not possible or is not a high priority.  Maybe if more of
us begged for it he would do it.  It is open source, so maybe somebody
else could do it.

You don't want just an ST-6 equivalent in software; you really want
regenerated Baudot to go to the printer.  Because there is something
like a 15dB disadvantage to Start-Stop TTY signals caused by the
mechanical selector in the machine.

What some people currently consider the best software demodulator is
2Tone, which does not run standalone but runs under N1MM Logger.  It
is free but closed source.  I don't know if one could figure out how to
use the 2Tone module with his own wrapper to make it function as a
simple demodulator.

Jim W6JVE