Verilink AS2000: The Basics (880-502981-001) Product Manual - Manual (Page 168)

Acronyms and Definitions
Glossary-48 Verilink Access System 2000: Basics
U
UART Universal Asynchronous Receiver
Transmitter—an integrated circuit
that converts parallel data to serial
data and vice versa.
UAS See unavailable second (UAS) .
UL See Underwriters Laboratory
(UL) .
unavailable second (UAS) Counted for every second in which
an unavailable signal state occurs.
This term is used by new
standards in place of failed
second (FS) .
unavailable signal state (UASS) Declared whenever 10 consecutive
severely errored second (SES) s
occur. The unavailable signal state
will not clear until 10 consecutive
seconds of data are processed with
no SESs present.
Underwriters Laboratory (UL) A company that tests equipment
for electronic safety. If the
instrument passes this company’s
tests, it is underwritten and given
the “UL” seal.
unipolar A signal stream in which all one
bits are the same polarity.
universal power supply (PWR 2940) The Verilink brick power supply
unit for the dual-line shelf that
accepts AC or DC inputs.
unprivileged password A Craft interface (ASCII) password
that permits an ASCII operator to
perform limited operations on a
module.
user register Any of various statistics kept in a
CSU for the previous 24 hours
according to Extended
Superframe Format (ESF)
specifications.