ADTRAN 1200063L1, Manual

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Appendix F. Glossary
F-2 DSU III TDM User Manual 61200063L1-20
BERT
bit error rate test. A known pattern of bits is transmitted and the errors
received are counted to figure the bit error rate. The idea is to measure the
quality of data transmission. The bit error rate is the ratio of received bits
that are in error, relative to the number of bits received. Usually expressed in
a power of 10.
CD
carrier detect. A signal generated by a modem or DSU/CSU. CD indicates
its connection status. If the CD light is on, the device is speaking to another
device.
channel service unit (CSU)
A device used to connect a digital phone line (T1 or Switched 56 line) com-
ing in from the phone company to either a multiplexer, channel bank, or
directly to another device producing a digital signal; for example, a digital
PBX, a PC, or data communications device. A CSU performs certain line-
conditioning and equalization functions, and responds to loopback com-
mands sent from the central office. A CSU regenerates digital signals. It
monitors them for problems, and provides a way of testing the digital circuit.
clocking
An oscillator-generated signal that provides a timing reference for a trans-
mission link. A clock provides signals used in a transmission system to con-
trol the timing of certain functions. The clock has two functions, (1) to
generate periodic signals for synchronization and (2) to provide a time base.
control port
An interface to a device or system that allows users to issue commands per-
taining to dialing, configuration, diagnostics, managements, etc.
controller card
The card installed in slot 1 of an ADTRAN Smart 16 shelf, used to connect a
VT 100 terminal or Datamate for configuring Smart 16 DSU/CSU products.
CPE
customer premise equipment. All telecommunications terminal equipment
located on the customer premises, including telephone sets, private branch
exchanges (PBXs), data terminals, and customer-owned coin-operated tele-
phones.