Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!decwrl!labrea!glacier!jbn
From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: comp.dcom.modems
Subject: 9600 baud over high-quality audio channel
Keywords: modem
Message-ID: <17507@glacier.STANFORD.EDU>
Date: 21 Jun 88 03:35:33 GMT
Organization: Stanford University
Lines: 16



     I'd like to transmit 9600 baud, simplex, (one-way) over a good-quality
audio channel that can handle at least 10KHz.  The transmit end must be
small and consume modest power; this is a telemetry application.  Telephone
oriented modems assume a much narrower audio bandwidth (about 3-4KHz) and
thus must use very elaborate techniques to cram 9600 baud into that narrow
a bandwidth.  I'm looking for something simpler, with about 1 baud/Hz
channel utilization.  This should be about as complex as a 2400 baud modem,
for which there exist single-chip versions such as the Fairchild
F2224.  But that chip can't be turned up to 9600 baud, as far as I know.
Any better ideas?

    The guys who want to push more bits through VHF FM repeaters might
have some ideas on this.

					John Nagle