25 Mar
2007
25 Mar
'07
1:50 a.m.
Hey Fred,
I think you should review Claude Shannon, if we are going to get into a bits
per bandwidth argument.
I think the bell 103, 203 standards for modems were still 1200, 2400 FSK
even if the baud was 110.
Thanks Fred, for reply, this modem stuff is my favorite topic at the moment.
I am working on my own implementation of all of these in a DSP.
Randy
From: Fred Cisin <cisin at xenosoft.com>
Reply-To: "General Discussion: On-Topic Posts Only" <cctech at
classiccmp.org>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Subject: Re: pretty much OT: acoustic coupling
Date: Sat, 24 Mar 2007 18:18:50 -0700 (PDT)
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What is the typical maximum
speed of such a device,
'twould seem that anything that goes through an analog/voice phone line
should work with acoustic coupling
OTOH, if you want to do FSK (Frequency shift keying), and want to do it by
counting cycles to differentiate the different tones, then think about how
many cycles you would need to identify a tone. If it is equal to, or more
than 1, then you're not going to get more bits per second than the lowest
tone's number of cycles per second. Therefore, you need to play games
with more than one bit per audio tone to get past about 1200 bits per
second.