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COMSPHERE 3900 Series Modems
GL-6 November 1996 3910-A2-GN32-30
extended network The extension of a circuit where the tributary DCE is connected to
a downstream (extended) control DCE.
extended r
esult codes
An asynchronous message (in either numbers or words) that
includes VF data rate and error control information the modem
sends to the DTE after executing or trying to execute a command.
fallback Retraining at a lower rate or speed.
FCC
Federal Communications Commission. Board of Commissioners
that regulates all interstate and foreign electrical communication
systems that originate from the United States.
Forward Err
or
Correction (FEC)
A method of error control for data transmission where the
receiving device can detect and correct a character or block of code
containing a predetermined number of erroneous bits.
Front-End Processor
(FEP)
A communications computer associated with a host computer that
manages the routing of data through the network.
full-duplex Simultaneous, two-way communications.
function key
Any one of three keys on the DCP that allows you to select or
increment an LCD entry. Function keys are labeled F1, F2, and F3.
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 the International Standards Organization (ISO).
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
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
.