NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/dcom/modems-part1/2095

Text File | 1996-08-05 | 3.8 KB | 77 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]>
Date: Sat, 20 Jan 1996 03:10:44 GMT


doug haire ([e-mail]) writes:
> John White ([e-mail]) wrote:
> : Nonsense!!!  Yes there are some significant problems with Rockwell
> : chipsets but reputable modem manufacturers (PPI, Supra) have
> : refined the code to the point where they are microscopic in comparison
> : to the bugs I was referring to in the Sportster. You seem to beleive
> : that if a modem does not use a Rockwell chipset it will ALWAYS be
> : better. Many hundreds of hours of my testing with Courier, Sportster
> : PPI, Supra etc. show this is not the case. My Courier with the latest
> : 33.6 code only marginally outperforms my PPI LCD. On a connection to a
> : provider using Courier upgraded to 33k I achieve 28.8 about 80% of the
> : time. With the LCD I achieve 28.8 50% of the time. Now 33k is really a
> : big deal isn't it?
>
> Apparently, it is. You see 80% 28.8k connects vs 50% 28.8k connects is
> significantly better. Incidently, how many 31.2k connects do you get with
> that PPI? I get 90% on a local call to one location (home data line to my
> BBS) and about 40% on a call from my office to BBS.

    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 was simply stating that from my testing 33.6k V34+ simply has not
> : shown itself to be a big boost in performance and was saying
> : that it is not a problem to not have 33.6K especially as implemented
> : now. Possibly in the future when code becomes more refined we will start
> : to see more performance improvements.
>
> There is more to that improvement than just the connect speed. Look into
> that Courier sometime and examine how it handles V.42 error correction.

    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.

> 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.

> 3200's to mid-3300's on a good 28.8k connect with my Supra using the same
> protocol.

    And that's the sort of range you'll get with a Sportster too.

Anthony


--
Anthony Hill | [e-mail]