NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/dcom/modems-part1/2171

Text File | 1996-08-05 | 4.1 KB | 82 lines

Newsgroups: comp.dcom.modems
Path: FreeNet.Carleton.CA!an171
From: [e-mail] (Anthony Hill)
Subject: Re: Is 33.6 only available for USR?
Message-ID: <[e-mail]>
Sender: [e-mail] (Anthony Hill)
Reply-To: [e-mail] (Anthony Hill)
Organization: The National Capital FreeNet
References: <4dd14b$[e-mail]> <4ddchf$[e-mail]> <[e-mail]> <4dh7j3$[e-mail]> <[e-mail]> <4dlt8f$[e-mail]> <[e-mail]> <4dqj68$[e-mail]>
Date: Sat, 20 Jan 1996 21:02:10 GMT


doug haire ([e-mail]) writes:
> Anthony Hill ([e-mail]) wrote:
> :     I believe that the original point of the message was that IF your
> : SNR is not good enough to support v.34 connections now, the new features
> : of the annex to v.34 will make NO difference in your connect speed
> : (assuming everything else is the same).  What this means is that if you're
> : getting a 26.4 connection with teh 3429 symbol rate with 28.8 v.34, you
> : will NOT see your connect speed increase to 28.8 by simply adding the 33.6
> : firmware UNLESS other things were changed (eg. when USR released their
> : 33.6 firmware for their Couriers).
>
> I believe there was a change included with the V.34+ upgrade (at least in
> the Courier) that improved speeds with the lower symbol rates, allowing a
> 28.8k connect (stable) at a lower symbol rate. I could be wrong about

    Yes, that is correct, and that's why I specified that the
connection was using the 3429 symbol rate already but still only getting a
26.4 connection due to poor SNR.  FWIW, the annex to v.34 allows all the
symbol rates to connect at one 2400bps higher then with the original v.34
spec, with the exception of the 2400 symbol rate (still stuck at 21.6
connections) and the 3429 symbol rate which can go up two steps (from 28.8
to 33.6).

> this but I don't think so. I do know, subjectively speaking, that my
> unstable 28.8k connects became more stable when I went to the V.34+ and
> that I started getting more 28.8k connects than I had. Admittedly, this
> is subjective since I did not run control tests.

    USR did some very effective refining of their v.34 code with their
33.6 code for their Couriers.  Sportsters saw many of the same refinements
with the 04/18/95 code.

> :     This has absolutely NOTHING to do with the annex to v.34, it's
> : merely coincidence that USR decided to add both new features in the same
> : firmware for their Couriers.  Also, unless something has changed since I
> : last checked, these new v.42 features (244 byte LAP-M packets and SREJ) have
> : NOT been added to the Sportster line.
>
> It was included in the V.34+ ROM code. As I understand it, it should also
> be in the Sporty V.34+ code but perhaps someone who has a V.34+ Sporty

    There's not particular reason why these enhancements should be
added with any one code.  They do not require any of the new features of
the annex to v.34, in fact, they don't require v.34 at all.  Zyxel's 14.4
modems (and 28.8s I presume) included both of the features that USR added
with their 33.6 code.

> : > You will find that it outperforms the "standard" implementation in the
> : > Rockwell chipset modems every time. That is, I get high 3300's to low
> : > 3400's using zmodem (w/Mobyturbo) on a 28.8k connection. I get high
> :
> :     FWIW the PPI has a maximum LAP-M packet size of 512 bytes, more
> : then twice the size of the USR Couriers 244 bytes, so the PPI will have a
> : higher maximum theoretical throughput then the USR Courier.  Of course,
> : PPI does not support SREJ (unless it's been added recentely), so if there
> : are any noticible amounts of errors on the line, the Courier may end up
> : outperforming the PPI.
>
> Would you run some tests with the PPI and see what kind of rates you get?
> I'd certainly be interested in seeing them.

    Several magazines did this a while back, the result was that PPI
and Hayes blew the competition out of the water on throughput tests (done
over perfect connections).

Anthony

--
Anthony Hill | [e-mail]