Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!rpi!image.soe.clarkson.edu!bkc
From: bkc@image.soe.clarkson.edu (Brad Clements)
Newsgroups: sci.electronics
Subject: How to send RS-232 over audio lines as an audio signal?
Message-ID: <1989Sep12.151538.4754@sun.soe.clarkson.edu>
Date: 12 Sep 89 15:15:38 GMT
References: <7871@cbmvax.UUCP>
Sender: bkc@sun.soe.clarkson.edu (Brad Clements)
Organization: Clarkson University, Potsdam, NY
Lines: 29

I need to pass RS-232 data over an audio line of dubious quality.
300 baud is the minimum (and acceptable) speed of transmission.
I was thinking of using a phase-lock-loop detector tacked onto
an RS-232 line driver on the output end, and a RS-232 receiver
and tone generator on the source end. This seems to work ok, except
that the PLL circuit has a holding cap and doesn't drop the output
line fast enough.

I've heard of FSK chips, but don't know where to start.

Can anyone recommend a simple chip set that would allow me to
pass RS-232 over an audio line (not a phone line, actually a
television intercom system). I only need one direction. Flow control
will not be needed.

I don't need a modem. This line will be carrying other audio 
signals at the same time. I'll be sending short (5 character)
sequences that can be retransmitted if garbled by noise.

Thanks

Brad Clements
Network engineer
Clarkson University
-- 

| Brad Clements          bkc@omnigate.clarkson.edu        bkc@clutx.bitnet 
| Network Engineer       Clarkson University              (315)268-2292