Nortel QMT12 ADM, Руководство пользователя

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Equipment description Page 31 of 80
Meridian Data Services Description
QMT8 SADM
The QMT8 has the same profile as the QMT7, but it supports both
asynchronous and synchronous data transmission. A service switch is used to
change from one mode of transmission to the other. The QMT8 can operate
in the same configuration as the QMT7.
The QMT8, when operating in the asynchronous mode, can operate at
19200 bps in addition to speeds specified for the QMT7. The QMT8 also
supports the inbound modem pooling and keyboard dialing features.
When operating in the synchronous mode, the QMT8 can transmit data at
1200, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 38400, 40800, 48000, or
56000 bps. Some of the QMT8 controls are different and are defined in
Table 2.
Note: For QMT8 with RS-232 interface at speeds above 20 kbps, the
EIA cable lengths (DTE or DCE to ADM) are speed-dependent and must
be shorter than 50 ft (15 m); e.g., in the 5 to 8 ft (1.5 to 2.5 m) range at
56 kbps.
QMT12 ADM
The QMT12 (V.35) ADM has the same profile as the QMT7 and QMT8.
However. the QMT12 provides high-speed V.35 CCITT synchronous instead
of a RS-232 interface to data terminals or modems. The QMT12 interface
conforms electrically to the CCITT V.35 standard and mechanically to
ISO-2110. The QMT12 provides for the same data transmission speeds as the
QMT8 synchronous ADM; 1200, 2400, 3600, 4800, 7200, 9600, 14400,
19200, 38400, 40800, 48000, or 56000 bps. The controls and option selectors
are similar to the QMT8 and are described in Tables 1 and 2.
Note: The RS-232-C (QMT8) DCE/DTE interface is normally used for
low-speed data rates (up to 19.2 kbps) while the V.35 (QMT12) interface
is used when high-speed (38.4 to 56.0 kbps) data rates are required.
However, synchronous terminals operate with whatever clock they
receive. Therefore, a user with a V.35 terminal can set the speed switch
to a low speed and call an RS-232 modem. A different color is used on
the speed indicator card of the QMT12 to indicate the higher speeds.
The V.35 CCITT interface should only be used in the synchronous operating
mode.