[GreenKeys] TU for Computer

[Craig Southeren]

My background is in VoIP, and I’ve spent a lot of hours working with software fax demodulators and modulators. There are quite a few of these as open source. Most work to 4800 baud, and some even do 9600 baud.

Modding one of these to do baudot FSK at 50 baud would be fairly simple. I might be interested in doing this if someone can provide a sample audio file

BTW: my first computer used a model 15 teletype for I/O. One of these days I’ll find get another noisy green monster so I can show my kids and grand kids what the past was really like

Sent from my iPhone

> On 11 Jan 2019, at 13:35, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
> 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
> 
> 
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