An Overview Of The V.90 Protocol - Motorola SM56 Quick Start User Manual

What does the logo mean for a product such as the SM56 modem? It means that Motorola and its
OEMs, system integrators, and VARs can use the Windows logo on their products and
packaging, and on advertising, collateral, and marketing materials. This signals end users that the
SM56 software modem is tested and fully functional on Windows 95/98 and Windows NT; that
it is designed to provide optimum usability and compatibility; and that it takes advantage of the
latest technologies provided by these operating systems. It makes users feel more comfortable
about purchasing the product, and it assures them of more complete satisfaction while using it.
The Windows logo also means that the qualified product gets included on Microsoft's Windows
Hardware Compatibility List (HCL) under "Logo," reinforcing to customers and end-users alike
that it meets Microsoft's strict requirements and operates properly with Windows operating
systems.
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An Overview of the V.90 Protocol

In February 1998, the International Telecommunications Union (ITU) formulated the V.90
industry-standard protocol for 56K modems. Before the adoption of the V.90 standard, 56K
modems complied with one of two pre-standard implementations: K56flex or X2 technology.
Unfortunately for ISPs and end-users, these technologies were not compatible. ISPs had to worry
about which standard to employ. End users had to be sure to purchase modems compatible with
their ISP's equipment.
Upgrading Motorola's SM56 K56flex modems to V.90 is a software-only upgrade. There is no
change to the line interface hardware. This makes it easy for pre-V.90 users to upgrade their
system to V.90 compliance.
Note: sometimes V.90 is referred to as V.PCM. PCM is an acronym for Pulse Code Modulation.
With V.90, high-speed downstream (from Internet to personal computer) data transmission is
accomplished using PCM techniques. Before the ITU formulated its standard V.90 protocol, the
industry typically referred to it as V.PCM. This name is fading from use.
V.90 technology allows users to connect to the Internet at rates up to twice as fast as those of
V.34 (33.6Kbps) modems. The maximum receive (downstream) rate is 56Kbps, while the return
path (upstream) connects at V.34 rates up to 33.6 Kbps. This is perfect for Internet connections,
where most data is transferred downstream.
The SM56 begins connections by attempting a V.90 connection to the headend. If the headend is
not V.90, the SM56 automatically switches to K56flex mode. If K56flex mode fails (when, for
example, the headend uses X2 technology, or there is a noisy phone line condition), the SM56
drops to V.34 rates. This auto-mode switching mechanism ensures maximum compatibility with
all remote headends.
On the Web you can visit www.v90.com for a wealth of information on V.90 technology,
including:
•
A list of ISPs that support V.90
•
The latest news on V.90