Glossary
Glossary-3
3920-A2-GN31-30
November 1996
circuit pack lock
A screw lock tab installed over a circuit card’s latch release tab to prevent the unit from
being removed without a tool. It is used on SDUs, modems, and filler panels.
command mode
One of two modem operating modes. When in Command mode, the modem accepts
commands instead of transmitting or receiving data.
compandor
A combination of a compressor at one point in a communication path for reducing the
volume range of signals, followed by an expandor at another point for restoring the
original volume range. Usually its purpose is to improve the ratio of the signal to the
interference in the path between the compressor and expandor.
configuration area
One of five areas within the Configure branch containing modem settings. Configuration
areas include Active (Operating), Active (Saved), Customer 1, Customer 2, and Factory.
configuration option
Modem software that sets specific operating parameters for the modem. Sometimes
referred to as straps.
connector
An outlet on equipment and cables that provides a connection.
constant carrier mode
The modem transmits a carrier signal constantly, regardless of RTS.
Control Channel (CC)
The diagnostic interface between a network management system and a network device.
control modem
A control modem polls downstream tributary modems across the analog channel.
controlled carrier mode
The modem’s transmitter turns on and off in response to RTS. This mode is used by
multipoint tributary modems.
Customer 1
A user-defined configuration area containing customized configuration options for a
specific application.
Customer 2
A user-defined configuration area containing customized configuration options for a
specific application.
DAA
Data Access Arrangement. Hardware that acts as a protective interface between the
telephone circuit and the modem. It performs such functions as ring detection, DC
isolation, and surge protection to protect the circuit from being disturbed by a modem
malfunction. The 392xPlus modems contain three dip switches that allow the DAA
hardware to be configured for use in different countries.
data bank
An area within the modem used to store the modem’s firmware. There are two data
banks in the 392xPlus modem.
data carrier
A continuous frequency signal that can be modulated by another signal that contains
information to be transmitted.
data compression
The elimination of empty fields, redundancies, and gaps in order to reduce storage
capacity needs and the amount of data to be transmitted. Anything that is eliminated is
restored after the data is received.
data mode
One of two modem operating modes. When in Data mode, the modem transmits and
receives data instead of accepting commands.
DB-25 connector
A 25-pin connector that is used to connect a cable which enables communication
between two devices.
