COMSPHERE 392xPlus Modems
Glossary-6
November 1996
3920-A2-GN31-30
idle
A state in which the modem’s operating parameters can be modified or commands can be
issued to the modem using either AT commands or the DCP.
JM8
A jack used for leased-line networks. Pins 1 and 2 are the transmit pair and Pins 7 and 8
are the receive pair.
keypad
A set of seven keys surrounding the DCP’s LCD. These keys are used to select
configuration options and to maneuver through the DCP menu.
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 telephone 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., an alarm).
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 local modem before disconnecting.
loopback test
Any test that verifies a device’s integrity by connecting the device’s output to the
device’s input, then checking the received signal for errors.
menu tree
The structure containing the menu hierarchy starting at a Top-Level menu and extending
down to various modem functions.
mixed inbound rates
In a multipoint network, several different data rates from tributary modems’ transmitters
communicating with one control modem.
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.
MSD
Modem Sharing Device. Allows from 2 to 4 physical ports to share a communication
channel.
multiplexer (mux)
A device that enables the simultaneous transmission of multiple independent data
streams into a single high-speed data stream.
multipoint line
A circuit connecting one control modem with one or more tributary modems.
Multiport mode
Multiport mode operates only in multiport modems. It is determined by your modem
model and the selected MUX mode configuration option. Multiport mode is in effect
when the MUX mode configuration option is set to TDM/MSD or DTE_Bridge. It
supports from one to four ports depending on how the modem is further configured.
