US Robotics COURIER Instrukcja Użytkownika Pobierz pdf (Strona 116)

U.S. Robotics I-modem Command Reference

Handshaking, Error Control, Data Compression, and Throughput • Page 11-7

connection. If the remote analog device does not have V.FC capability, the I-modem lis-

tens to the deviceÕs answer tones to identify what standard rate the remote analog device is

operating at, and then adjusts to that rate.

When the I-modem answers a call from an analog device, the I-modem sends out a series

of answer tone signals until both devices negotiate the best connection rate.

USR V.32terbo to USR V.32terbo

On these analog connections, I-modems have two features that result in outstanding per-

formance: Quick Connect and Adaptive Speed Leveling (ASL).

Quick Connect allows the devices to connect in approximately 7 seconds, a far shorter

time than with most devices.

ASL (described below in Other V.Protocols) is used by I-modems operating in V.32terbo

and V.32bis modes.

Other V. Protocols

Earlier, lower-speed ÒV.Ó protocols do not employ line probing. Instead they use pre-

deÞned answer tones to specify or identify speed capabilities. These protocols deÞne the

following maximum speeds:

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US Robotics COURIER Instrukcja Użytkownika Strona 116