A message from Dale Walsh, Vice President of Advanced Development for USR:

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 a 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
