Re: 288 to 336

Jay Shoup (jashoup@indiana.edu)
Mon, 15 Apr 1996 16:26:10 +5000


I would be sure to check and see if you are able to connect to
another 28.8 modem other than a sportster on any line.

There are two factors that you need to consider when defining a
modems ability to connect at 28.8. 1st is line quality. 28.8 requires
very good line quality, low noise, low phase distortion, and low
harmonic distortion. If the phone line is not just about perfect the
modem will not connect at 28.8 but rather will 'fall-back' to a lower
more adequate speed.. Just because it connected before does not imply
that that you have a good line. The line quality is measured
end-to-end. It is NOT a measurement of YOUR line quality, but rather a
measure of total line quality and is influenced by factors beyond your
control. Factors such as water in a phone line, line impedance, and
other noise causing factors will change from day to day, even hour to
hour. Other things such as impedance matching at the phone companies
switching equipment can change on a line per line bases.

USR claims there modem will connect at 33.6, this may be true,
but once again the line must be pretty close to perfect. Any noise,
(static, pop, hiss,), distortion etc. will cause the modem to
'fall-back'. USR claims they have improved hardware to help on less
than perfect line, I am not convinced.

This brings me to the second requirement for modems, compatibility,
USR has had a long history of implementing their own versions of
standards, IE "HOST" mode.....It was not compatible with any other
modems that I know of. Their first implementations of V32 was not (in
my opinion) completely compatible, that is why they had to upgrade
many USR V32 users modems so that they would work with other
manufactures modems. I understand the same may be true with their V34
implementation. The did I believe offer an upgrade to correct the
problem for the sportster modem not to long ago.

USR's history of compatibility has not impressed me, I doubt very
seriously that they ever will.

Legal disclaimer:

The above statements are the opinion of the author and should not be
construed as statements of fact.

> David I. Sommers, Ph.D. wrote:
> > I upgraded ny Sportster from 288 to 336 and now consistently log-on at 24000.
> > It seems to me that the limiting factor is how the ISP is set up rather than anyt
> >
> > David Sommers
>
> Greetings:
> This is unfortunate as I cannot see how ANY ISP would want to limit the B/W of
> their customers?!? Maybe, if you can try out other ISP locations with 28.8 baud
> support, you will see the difference.
>
> Good luck,
> [=============================================================================]
> "THERE IS NO SANITY... Just organized CHAOS!!!"
> "I'ld rather STAND CORRECTED than SIT CONFUSED!!!"
>
> Daniel W. Erskine "mailto:derskine@apci.net"
> PHONE: (JOB) HUN-TING "http://www.apci.net/~derskine"
> [=============================================================================]
>
>

Jay!
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Jay Shoup
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Indiana University
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