ADTRAN ISU 512e Manual page 145

certain line-conditioning functions, ensures network compliance
per FCC rules, and responds to loopback commands from the cen-
tral office. Also ensures proper 1s density in transmitted bit
stream and performs bipolar violation correction. See DSU.
D-channel
The ISDN channel that carries signaling information to control the
call setup, teardown, or invocation of supplementary services.
The D-Channel may also be used to provide Packet Mode Data
Service.
DCE
Data communications equipment. The portion of a data terminal
that provides the interface to the network.
DDS
Dataphone digital service. AT&T private line service for transmit-
ting data over a digital system. The digital transmission system
transmits electrical signals directly, instead of translating the sig-
nals into tone of varied frequencies as with traditional analog
transmission systems. Digital techniques provide more efficient
use of transmission facilities, resulting in lower error rates and
costs than analog systems.
digital loopback
Technique for testing the digital processing circuitry of a commu-
nications device. May be initiated locally or remotely via a tele-
communications circuit. Device being tested will echo back a
received test message after first decoding and then encoding it.
The results are compared with the original message (compare
with analog loopback).
DSU
Data service unit. A device providing an interface between a data
terminal or other data communications device and a digital access
line.
DTE
Data terminal equipment. The portion of a data terminal that in-
terfaces to the end-user's equipment. The main difference be-
tween DCE and DTE is that pins 2 and 3 are reversed on the RS-
232.
EIA-232
An EIA-specified physical interface with associated electrical sig-
naling between DCE and DTE. The most commonly employed
interface between computer devices and modems.
61203086L1-1 ISU 512e User Manual
Glossary
Glossary-3