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Path: utzoo!utgpu!water!watmath!clyde!rutgers!rochester!cornell!batcomputer!pyramid!octopus!pete
From: pete@octopus.UUCP
Newsgroups: comp.dcom.modems
Subject: Re: Looking for a fast modem < $1000.
Message-ID: <371@octopus.UUCP>
Date: Mon, 7-Dec-87 14:16:43 EST
Article-I.D.: octopus.371
Posted: Mon Dec  7 14:16:43 1987
Date-Received: Sat, 12-Dec-87 19:00:50 EST
References: <48400001@uxe.cso.uiuc.edu> <7753@g.ms.uky.edu> <8093@ism780c.UUCP> <7826@g.ms.uky.edu>
Reply-To: pete@octopus.UUCP (Pete Holzmann)
Organization: Octopus Enterprises, Cupertino, CA
Lines: 35
Summary: Telebit falls back in 2bps increments

In article <7826@g.ms.uky.edu> david@ms.uky.edu (David Herron -- Resident E-mail Hack) writes:
>In article <8093@ism780c.UUCP> tim@ism780c.UUCP (Tim Smith) writes:
>>I seem to recall that the proposed standards ( e.g., from ISO ) suck.
>>They do things like fall back from 9600 to 4800 if there is too much
>>line noise.  The Trailblazer is much better.
>
>The trailblazer will fall back as well, but in 300 baud speed increments
>instead of 4800 baud increments.
>

Unless I am mistaken, the trailblazer falls back in 17.5 bps increments; at 
least, that's what the transmit/receive bits-per-channel reports indicate. For 
those of you who haven't yet joined the ranks of happy users: the modem has 
several reports available if you inquire the value of certain S-registers. 
Two of these show, for each of 511 bands spaced 7.8 Hz apart, how many bits 
are being sent or received in each band. The number of bits/band adjusts 
as a value in the set (0,2,4,6) individually for each band. If you compare
these numbers with the instantaneous transmit/receive rate (available in 
another S-register), you find that a change of 2 in a single band corresponds
to approximately 17.5 bps change in the data rate. Note that since the modem
performs buffered data rate translation, there is no need for the host CPU
to know any of these details: on a bad line, the data throughput just goes
down!

In case you're wondering what kind of modem would have detailed reports
like this... that's only the beginning. There's even a report that shows line
noise level in each of the 512 bands in dBm to the nearest tenth! This thing
could probably be reprogrammed to be a nice signal analyzer.

Disclaimer: Just another (very) satisfied customer.
-- 
  OOO   __| ___      Peter Holzmann, Octopus Enterprises
 OOOOOOO___/ _______ USPS: 19611 La Mar Court, Cupertino, CA 95014
  OOOOO \___/        UUCP: {hpda,pyramid}!octopus!pete
___| \_____          Phone: 408/996-7746