Path: utzoo!attcan!uunet!husc6!mailrus!ames!umd5!umbc3!cbw1!brian
From: brian@cbw1.UUCP (Brian Cuthie)
Newsgroups: comp.dcom.modems
Subject: Re: 9600 baud over high-quality audio channel
Keywords: modem
Message-ID: <189@cbw1.UUCP>
Date: 26 Jun 88 00:58:48 GMT
References: <17507@glacier.STANFORD.EDU> <5063@videovax.Tek.COM>
Reply-To: brian@cbw1.UMD.EDU (Brian Cuthie)
Organization: CBW, Columbia, MD 21046
Lines: 25

In article <5063@videovax.Tek.COM> bill@videovax.Tek.COM (William K. McFadden) writes:
>
>>     I'd like to transmit 9600 baud, simplex, (one-way) over a good-quality
>>audio channel that can handle at least 10KHz.
>
>This might seem too obvious, but why not connect the output of your RS-232 port
>directly to the input of your audio channel (using suitable attenuation and DC
>blocking)?  At the receive end you would probably want some sort of active
>filtering and schmitt triggering to recover the data.  The problems I could

The first problem I see with this is that the audio path is not DC coupled
and thus you would have big problems with data that was all marking.  Now if
you MFM encoded the data you might get by, but I doubt it.  This is why
people invented modems for phone lines (audio channels -- right ?).

-brian

CASE Communications Inc.
High Speed Modem Group
Columibia, MD 21046
-- 
Brian D. Cuthie                                 uunet!umbc3!cbw1!brian
Columbia, MD                                    brian@umbc3.umd.edu
"Captain, Captain! All the stars have gone out!"
"No, you fool,you've leaned on the button.  Turn the viewer back on!"