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From: bsmith@rose.cis.ohio-state.edu (brentley r smith)
Newsgroups: comp.dcom.modems
Subject: Re: V32bis
Message-ID: <87110@tut.cis.ohio-state.edu>
Date: 8 Jan 91 21:54:45 GMT
References: <19700002@inmet> <3713.27832d53@hayes.uucp>
Sender: news@tut.cis.ohio-state.edu
Reply-To: brentley r smith <bsmith@cis.ohio-state.edu>
Organization: The Ohio State University (in Cowtown, USA)
Lines: 26

In article <3713.27832d53@hayes.uucp> tnixon@hayes.uucp writes:
=>In article <19700002@inmet>, gregh@inmet.inmet.com writes: 
=>=>   A friend of mine wanted to know how V32bis achieves 14400 bps. 
=>=>   What in short does V32bis do differently from V32 to achieve the faster
=>=>   speed?
=>
[much deleted]
=>
=>Since V.32 was standardized, modem technology has progressed so that 
=>it's possible to transmit and received more complex signals with 
=>greater resolving capability.  In V.32bis, all that was done is 
=>permit more combinations of phase and amplitude.  At 12000bps, there 
=>are 64 possible conbinations, and at 14400bps, there are 128 
=>possible combinations.  V.32bis also permits 7200bps transmission, 
=>with 16 possible combinations.  In all three of these cases, trellis 
=>coding is used as at 9600bps; thus, the number of user bits per 
=>symbol period sent at 7200 is 3, 12000 is 5, and 14400 is 6.
=>
[much deleted]

How does V.32bis compare to "HST", U.S. Robotics' proprietary protocol?
Are teh mechanics of the protocols similar?  Is the (theoretical) 
throughput similar?

Brentley Smith
bsmith@cis.ohio-state.edu