Installation manual

COMSPHERE 3000 Series Carrier
Glossary-6 March 2001 3000-A2-GA31-F0
LAN Local Area Network. A network that spans a small geographic area (e.g., a building).
LATA Local Area Transport Area. A region served by a LEC that consists of one or more area
codes.
LCD Liquid Crystal Display. Thin 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
can be displayed.
LDM Limited-Distance Modem (also called a local area data set or LADS).
leased line A private telephone line connection exclusively for the user. No dialing is necessary.
LEC Local Exchange Carrier. A company that provides intra-LATA (local exchange carrier)
telecommunications services, like NYNEX or Bell South.
LED Light-Emitting Diode. A light or status indicator on the control panel that glows in response
to the presence of a certain condition (e.g., an alarm).
Make Busy An additional capability for DDD NIMs. This feature is useful when modems are used in a
‘‘hunt” or ‘‘rotary” group. The Make Busy feature ties the Tip and Ring signals together so
that the modem appears busy.
MCMP Multichannel Multipoint. A circuit card that enables the support of up to six independent
applications over a single multipoint digital facility. The MCMP capability can support up to
40 tributary DSUs, each optioned with an MCMP card.
MI/MIC Mode Indicate and Mode Indicate Common. A control signal method which causes the
associated modem to go off-hook in the Originate mode. With MI/MIC signaling, two leads
are provided, usually via Pins 3 and 6 of an 8-position modular VF connector: Mode
Indicate and Mode Indicate Common. Actuation of the signal is by momentary connection
of these two leads.
modem MOdulator/DEModulator. A device used to convert data from a digital signal to an analog
signal so that data can be transmitted over a telephone line. Once the data is received, the
analog signal is converted back into a digital signal.
modular circuit card A circuit card that contains gold finger contacts on the rear edge of the circuit card. A
modular circuit card can be removed from the front of the carrier without disturbing DTE
cables.
multiplex To combine many low-speed data sources into a single, high speed serial data stream. The
data is coded at transmission, and decoded at reception. Some multiplexing techniques
include Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), and
Statistical Multiplexing (Stat MUX).
multipoint circuit A special type of circuit where one control device communicates in a broadcast mode with
one or more tributary devices. Communication from a tributary device is always directly to
the control device, and not to any of the other tributary devices.
multipoint line A circuit connecting one control modem with one or more tributary modems.
MUX Multiplexer. A device that enables the simultaneous transmission of multiple independent
data streams into a single high-speed data stream.
network address The user-assigned identification number for a particular device. The network address is used
by a node to communicate with other nodes connected to it.