SUBJECT:Clearing up V.34 confusion

The following is a message from Dale Walsh, U.S. Robotics Vice President
of Advanced Development.  Please do not reply to this message as I read
this ID infrequently, and messages to US Robotics should be addressed to
one of the standard ID's :

SYSOP SUPPORT
SYSOP
TECHNCIAL SUPPORT
------------------------------------------------

As a member of the ITU-T Study Group 14, I'd like to clear up some of
the confusion about the new V.34 standard.

Something unique to V.34 is the amount of cooperation that's happened
between vendors.  U.S. Robotics, Motorola Codex, AT&T, AT&T Paradyne,
Cornel (in Ireland) and perhaps other companies have all done up-front
data-pump compatibility testing to ensure that V.34 products are
compliant with the standard and interoperate.  Rest assured that as
other manufacturers develop working prototypes, they will join the list.
 This is the direction companies are spending their engineering. It
doesn't help any of us if our products don't work well together.  That's
the purpose of V.34 -- to have an international standard for 28.8.

A lot of new ideas and technology have been developed in conjunction
with the standard, and what we as a committee originally envisioned has
changed significantly.  There have been some outstanding discoveries and
developments made in the process, a few of which were also used in
proprietary pre-V.34 modems.

But, V.34 has it all:  precoding, which compensates for severe amplitude
distortions; powerful multidimensional trellis coding; constellation
shaping and other innovations that give V.34 a greater immunity to
noise; nonlinear coding, which addresses the problem of signal peaks
being distorted due to non-linear circuit elements; and line probing,
which enables V.34 to quickly examine line conditions and select the
best transmission strategy to optimize data transmission. V.34 also uses
an channel probing technique that can detect certain unusual non-linear
distortion mechanisms present on some phone circuits, especially on
international circuits. The modems can then select operational modes
that better combat distortion.

All 28.8 modems are not created equal.  The goal of a modem protocol is
not only to have a high top speed, but to spend as much of the time as
possible operating at the highest
possible speed under changing conditions.  The V.34 protocol has
advanced procedures for training and for recovery from transient
disturbances during training. There are several retrain procedures to
insure link integrity under adverse conditions.  Rate renegotiation
procedures allow rapid switching ranging from 4800 to 28800 bits/s as
the channel conditions vary.

Additionally, V.34 will be the enabling springboard for a host of new
applications -- low bit rate video and audio graphic conferencing are
new applications that will capitalize on the increased V.34 bit rate and
because it is an international standard.

In fact, the overriding benefit of V.34 is that it IS an international
standard.  Many of U.S. Robotics' corporate customers have been waiting
for the V.34 standard to be approved because they know it will be
supported by a larger number of vendors than any proprietary protocol.

I hope this information is helpful.  Please feel free to e-mail me at
dwalsh@usr.com with any further questions or concerns.

Regards,

Dale Walsh
Vice President of Advanced Development U.S. Robotics, Inc.
Member of ITU-T Study Group 14