[GreenKeys] Introduction - And Looking for Sagem TX20 information

[Andreas Müller]

Hi Malcolm,
if you want to use your teleprinters, you might have a look at the telexphone 
project on www.teleprinter.net. As far as I remember, there are already 
Australian members.
Regards
Andreas

Am Montag, 26. Mai 2008 04:46 schrieb Malcolm Macleod:
> Greetings,
>
>
>
> I am new to your list.  It is great to see such an active list for these
> lovely old machines.
>
>
>
> I have a couple of old teleprinters (Models 15 and 100) put away for future
> restoration, but my short-term project involves a Sagem TX20 Telex machine
> I acquired here recently in Melbourne, Australia.  I am interested in
> driving it with a microcontroller board to effectively create a telex
> simulator (basically a simulator that can exchange messages between the
> TX20 and a locally-connected PC).  I want the simulator to be capable of
> generating/decoding the original dialing, negotiation and answer-back
> protocols etc, as well as the exchange of data.
>
>
>
> My first challenge though is getting information about both the interfacing
> _and_ day-to-day use of the TX20.  Does anyone know of any relevant
> resources that may be available on the web relating either specifically to
> the TX20, or to the FSK/PSTN telex interface generally?  If possible, my
> plan is to build an interface that connects directly to the TX20's modem
> (possibly using an old PC external modem in a direct-connect loop?).  If
> that is technically too complicated, I am hoping it might be possible to
> connect to a current-loop interface within the TX20 (if it exists!).
>
>
>
> Any thoughts? In particular, are the Telex mark/space frequencies
> compatible with those used in PC external modems?  If they are not
> compatible, how complicated is it to decode the frequencies by using a PLL
> detector driven from a 600 ohm isolation transformer on a local loop?
>
>
>
> Malcolm.
>
>
>
> _______________________________________________
> GreenKeys mailing list
> GreenKeys at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/greenkeys