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COMSPHERE 3800Plus Modems
Glossary-6 November 1996 3980-A2-GB30-20
LCD Liquid
Crystal Display
. A thin sandwich of two sealed glass plates containing liquid
crystal material. When voltage is applied, the amount of light able to pass through the
glass plates is altered so that messages may be ‘
‘written” on the display.
leased line
A private line connection exclusively for the user
. No dialing is necessary
.
LED Light-Emitting Diode. A light or status indicator on the DCP that glows in response to
the presence of a certain condition (e.g., Alrm).
local analog loopback The modem’
s transmit VF signal is looped to its receiver
.
long space disconnect A disconnect can occur if the modem receives an extended space from a remote modem;
for example, when a remote modem is commanded to disconnect, it transmits a
continuous space to the modem before disconnecting.
loopback test Any test that verifies a device’s integrity by connecting the device’s output of one
direction to the device’s input of the other direction, then checking the received signal for
errors.
LSD Line Signal Detect. A signal between the DTE and modem indicating ener
gy exists on
the transmission circuit.
menu tree The structure containing the 3800Plus menu hierarchy starting at a Top-Level menu and
extending down to various modem functions.
MNP This protocol (Microcom Networking Protocol) detects and corrects data errors caused
by telephone line noise and signal distortion. MNP5 includes data compression.
modem (Modulator/DEModulator). A device that transforms signals from digital to analog form
and vice versa.
modulation The process of varying some characteristics (usually amplitude, frequency, and/or phase)
of a carrier wave to form data transmissions.
network A communications circuit.
network address The customer-assigned diagnostic address of a tributary modem.
NIM Network Interface Module. The interface provided, up to two per carrier, for the public
switched telephone network (PSTN) used by 3811Plus
modems.
NMS
Network Management System. A set of diagnostic and configuration management tools
for a data communication network, consisting of software programs and dedicated
computer hardware.
off-hook The condition of a telephone or modem that is being used to establish or maintain
communication.
offline The condition of a modem that is not connected to another modem.
on-hook The condition of a telephone or modem that is not being used.
online The condition of a modem that is connected to and communicating with another modem.