User`s guide

G-2 DL600E E1 Data Multiplexer UserÕs Guide
circuitÑGenerally referring to a transmission medium connecting two or
more electronic devices.
clear channelÑA characteristic of a transmission path or digital circuit in
which the full bandwidth is available to the user. The phone company does
not use any portion of the bandwidth for framing or control bits.
clockÑAn oscillator-generated signal providing a timing reference for a
transmission link; used to control timing functions such as sampling interval,
signaling rate and duration of signal elements.
code conversionÑThe process of changing the bit grouping for a character in
one code into the corresponding bit grouping for the character in another.
Code Violation (CV)ÑA code violation occurs when the ones bit is not repre-
sented with the opposite signal of the previous ones bit.
communications port (Comm Port)ÑThe electrical interface between a unit
and the operatorÕs terminal. Operator commands and responses can be com-
municated through the Comm Port.
connectorÑA physical interface, such as DA15 or RS232-C, typically with
male or female components.
CPE (Customer Premises Equipment)ÑEquipment that interfaces the tele-
phone network and physically resides at the user's location.
CRC (Cyclic Redundancy Check)ÑA link-level error checking feature used
when additional protection is needed against simulation of the frame align-
ment signal and/or when an enhanced error monitoring capability is needed.
A CRC calculation is performed and four frame bits are used to store it over
the content of the frame. The
CRC calculation is performed again when the
frame is received and the
CRC values are compared. If they do not match, the
frame is considered bad and the
CRC statistic is incremented.
CSU (Channel Service Unit)ÑThe CPE used to terminate a digital circuit at
the customer site. It performs certain line-conditioning functions, ensures net-
work compliance to
FCC rules and responds to loopback commands. It
ensures proper ones density in the bit stream and performs bipolar violation
correction. A
DSU and CSU are often in the same unit, called a DSU/CSU.
CTS (Clear to Send)ÑA signal issued by the DSU to indicate it is connected
to the digital network and is ready to accept data.
CV (Code Violation)ÑOccurs when the ones bit is not represented with the
opposite signal of the previous ones bit.