Motorola SM56, Быстрый старт Руководство пользователя

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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
•
White papers on the V.90 standard
•
Technology descriptions
•
Frequently asked questions (FAQs)
Appendix A: SM56 Specifications
•
Full Windows 95/98 compatibility; received Microsoft Designed for Windows Logo
•
Compatibility with Windows 95/98 communication applications
•
Compatibility with communications applications that run in an MS-DOS® box
•
An installation engine with country selection. (Selecting the correct country during installation
is important, since this selects between A-Law and
µ
-Law
compansion)
•
Plug and Play operation
•
Support for various data modulation modes:
- V.90 connection rates if the headend is a true V.90 location. V.90 downstream rates to
56Kbps. Upstream rates to 33.6Kbps (V.34).
- Fallback to K56flex® mode if the headend is K56flex, not V.90. K56flex® downstream
rates to 56Kbps. Upstream rates to 33.6Kbps(V.34).
- Connection at V.34 rates (33.6 Kbps) if the headend is not V.90 or K56flex®.
- V.32bis, V.32, V.22bis, V.23, V.22/B212, V.21, Bell 103.
•
Error correction - V.42, LAPM, MNP2-4
•
Data compression - V.42bis, MNP5
•
Fax modes supported - V.17, V.27ter, V.29
•
Full voice support on Data/Fax/TAM/Speakerphone modems...where TAM is Telephone
Answering Machine.