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From: bill@bilver.UUCP (Bill Vermillion)
Newsgroups: comp.dcom.modems
Subject: Re: Recording of Modem output
Message-ID: <1081@bilver.UUCP>
Date: 7 Oct 90 07:04:22 GMT
References: <1990Oct6.114313.9227@wubios.wustl.edu>
Reply-To: bill@bilver.UUCP (Bill Vermillion)
Organization: W. J. Vermillion - Winter Park, FL
Lines: 37

In article <1990Oct6.114313.9227@wubios.wustl.edu> phil@wubios.wustl.edu (J. Philip Miller) writes:
>[I posted this earlier, but don't think it left here -jpm]
>
>I would like to know if it is possible to record the output of a modem and
>later play it back into the modem and recover the original digital signal?
>If so what black boxes (if any) do I need.
>

That used to be quite common, and one of the modems I had (many years ago)
had jacks to be able to connect to a cassette machine.  The idea was that
it was much cheaper to put a big program on a cassette and mail it,
particularly when going between different computers, eg CPM to APPLE, or
similar applications.

You should be able to do the same with any device that will let you connect
to the phone line, as the modem signals are just audio at that point.  You
are right in wanting to do it at 300bps however, as the FSK is much easier
to record and playback reliably than the PSK.


>My recollection of the technology would suggest that it would be easiest to do
>with the FSK of 300 baud modems (which would be plenty fast enough for my
>application) technology.
>
>Has anyone done this?  If so what did you have to do to connect the modem to a
>recorder?  Since a phone line normally has a voltage, does one have to be
>supplied?

And I can't remember the name of the company that made the modems.  It was
in the early days, before Hayes made such inroads.  I do remember that I
had that modem before IBM introduced their PC in August of 1981.



-- 
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
                      : bill@bilver.UUCP