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COMSPHERE 3800 Series Modems
Glossary-6 November 1996 3810-A2-GB30-20
Gr
oup III
A fax standard that specifies a rate of transmission of about one page per minute.
half-duplex Two-way data communications allowed in only one direction at a time.
handshaking
The exchange of predetermined codes and signals (tones) to establish a connection
between two modems.
HDLC High-Level Data Link Control. A communications protocol defined by ISO.
hidden choice indicator A symbol appearing in the upper right-hand corner of the LCD, indicating that more
selections are available than what appears on the LCD.
host A computer attached to a network that shares its information and devices with the rest of
the network.
Hz A unit of frequency (hertz) that equals one cycle per second.
idle A state in which the modem’s operating parameters can be modified or commands can be
issued to the modem using either A
T 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.
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 3800 Series 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.